This document has been produced from the texinfo file zsh.texi
,
included in the Doc
sub-directory of the Zsh distribution.
The texinfo source may be converted into several formats:
The Info format allows searching for topics, commands, functions, etc.
from the many Indices. The command ‘makeinfo zsh.texi
’ is used to
produce the Info documentation.
The command ‘texi2dvi zsh.texi
’ will output zsh.dvi
which can
then be processed with dvips and optionally gs (Ghostscript) to
produce a nicely formatted printed manual.
An HTML version of this manual is available at the Zsh web site via:
https://zsh.sourceforge.io/Doc/
.
(The HTML version is produced with texi2html, which may be obtained
from http://www.nongnu.org/texi2html/
. The command is
‘texi2html --output . --ifinfo --split=chapter --node-files zsh.texi
’.
If necessary, upgrade to version 1.78 of texi2html.)
For those who do not have the necessary tools to process texinfo,
precompiled documentation (PostScript, dvi, PDF, info and HTML formats)
is available from the zsh archive site or its mirrors, in the file
zsh-doc.tar.gz
. (See Availability for a list of sites.)
Zsh is a UNIX command interpreter (shell) usable as an interactive login shell and as a shell script command processor. Of the standard shells, zsh most closely resembles ksh but includes many enhancements. It does not provide compatibility with POSIX or other shells in its default operating mode: see the section Compatibility.
Zsh has command line editing, builtin spelling correction, programmable command completion, shell functions (with autoloading), a history mechanism, and a host of other features.
Zsh was originally written by Paul Falstad. Zsh is now maintained by
the members of the zsh-workers mailing list <zsh-workers@zsh.org>
.
The development is currently coordinated by Peter Stephenson
<pws@zsh.org>
. The coordinator can be contacted at
<coordinator@zsh.org>
, but matters relating to the code should
generally go to the mailing list.
Zsh is available from the following HTTP and anonymous FTP site.
ftp://ftp.zsh.org/pub/
https://www.zsh.org/pub/
The up-to-date source code is available via Git from Sourceforge. See
https://sourceforge.net/projects/zsh/
for details. A summary of
instructions for the archive can be found at
https://zsh.sourceforge.io/
.
Zsh has several mailing lists:
<zsh-announce@zsh.org>
Announcements about releases, major changes in the shell and the monthly posting of the Zsh FAQ. (moderated)
<zsh-users@zsh.org>
User discussions.
<zsh-workers@zsh.org>
Hacking, development, bug reports and patches.
<zsh-security@zsh.org>
Private mailing list (the general public cannot subscribe to it) for discussing bug reports with security implications, i.e., potential vulnerabilities.
If you find a security problem in zsh itself, please mail this address.
To subscribe or unsubscribe, send mail to the associated administrative address for the mailing list.
<zsh-announce-subscribe@zsh.org>
<zsh-users-subscribe@zsh.org>
<zsh-workers-subscribe@zsh.org>
<zsh-announce-unsubscribe@zsh.org>
<zsh-users-unsubscribe@zsh.org>
<zsh-workers-unsubscribe@zsh.org>
YOU ONLY NEED TO JOIN ONE OF THE MAILING LISTS AS THEY ARE NESTED. All submissions to zsh-announce are automatically forwarded to zsh-users. All submissions to zsh-users are automatically forwarded to zsh-workers.
If you have problems subscribing/unsubscribing to any of the mailing
lists, send mail to <listmaster@zsh.org>
.
The mailing lists are archived; the archives can be accessed via the
administrative addresses listed above. There is also a hypertext
archive available at
https://www.zsh.org/mla/
.
Zsh has a list of Frequently Asked Questions (FAQ), maintained by
Peter Stephenson <pws@zsh.org>
. It is regularly posted to the
newsgroup comp.unix.shell and the zsh-announce mailing list.
The latest version can be found at any of the Zsh FTP sites, or at
https://www.zsh.org/FAQ/
. The contact address for FAQ-related matters
is <faqmaster@zsh.org>
.
Zsh has a web page which is located at https://www.zsh.org/
.
The contact address for web-related matters is <webmaster@zsh.org>
.
A userguide is currently in preparation. It is intended to complement the
manual, with explanations and hints on issues where the manual can be
cabbalistic, hierographic, or downright mystifying (for example, the word
‘hierographic’ does not exist). It can be viewed in its current state at
https://zsh.sourceforge.io/Guide/
. At the time of writing, chapters
dealing with startup files and their contents and the new completion system
were essentially complete.
sh(1), csh(1), tcsh(1), rc(1), bash(1), ksh(1)
IEEE Standard for information Technology - Portable Operating System Interface (POSIX) - Part 2: Shell and Utilities, IEEE Inc, 1993, ISBN 1-55937-255-9.
The Zsh Manual, like the shell itself, is large and often complicated. This section of the manual provides some pointers to areas of the shell that are likely to be of particular interest to new users, and indicates where in the rest of the manual the documentation is to be found.
When it starts, the shell reads commands from various files. These can be created or edited to customize the shell. See Files.
If no personal initialization files exist for the current user, a function
is run to help you change some of the most common settings. It won’t
appear if your administrator has disabled the zsh/newuser
module.
The function is designed to be self-explanatory. You can run it by hand
with ‘autoload -Uz zsh-newuser-install; zsh-newuser-install -f
’.
See also
User Configuration Functions.
Interaction with the shell uses the builtin Zsh Line Editor, ZLE. This is described in detail in Zsh Line Editor.
The first decision a user must make is whether to use the Emacs or Vi
editing mode as the keys for editing are substantially different. Emacs
editing mode is probably more natural for beginners and can be selected
explicitly with the command bindkey -e
.
A history mechanism for retrieving previously typed lines (most simply
with the Up or Down arrow keys) is available; note that, unlike other
shells, zsh will not save these lines when the shell exits unless you
set appropriate variables, and the number of history lines retained by
default is quite small (30 lines). See the description of the shell
variables (referred to in the documentation as parameters) HISTFILE
,
HISTSIZE
and SAVEHIST
in Parameters Used By The Shell. Note that it’s
currently only possible to read and write files saving history
when the shell is interactive, i.e. it does not work from scripts.
The shell now supports the UTF-8 character set (and also others if
supported by the operating system). This is (mostly) handled transparently
by the shell, but the degree of support in terminal emulators is variable.
There is some discussion of this in the shell FAQ,
https://www.zsh.org/FAQ/
. Note in particular that for combining
characters to be handled the option COMBINING_CHARS
needs to be set.
Because the shell is now more sensitive to the definition of the
character set, note that if you are upgrading from an older version of
the shell you should ensure that the appropriate variable, either
LANG
(to affect all aspects of the shell’s operation) or
LC_CTYPE
(to affect only the handling of character sets) is set to
an appropriate value. This is true even if you are using a
single-byte character set including extensions of ASCII such as
ISO-8859-1
or ISO-8859-15
. See the description of LC_CTYPE
in
Parameters.
Completion is a feature present in many shells. It allows the user to
type only a part (usually the prefix) of a word and have the shell fill
in the rest. The completion system in zsh is programmable. For
example, the shell can be set to complete email addresses in
arguments to the mail command from your ~/.abook/addressbook
;
usernames, hostnames, and even remote paths in arguments to scp, and so
on. Anything that can be written in or glued together with zsh can be
the source of what the line editor offers as possible completions.
Zsh has two completion systems, an old, so called compctl
completion
(named after the builtin command that serves as its complete and only
user interface), and a new one, referred to as compsys
,
organized as library of builtin and user-defined functions.
The two systems differ in their interface for specifying the completion
behavior. The new system is more customizable and is supplied with
completions for many commonly used commands; it is therefore to be
preferred.
The completion system must be enabled explicitly when the shell starts. For more information see Completion System.
Apart from completion, the line editor is highly extensible by means of shell functions. Some useful functions are provided with the shell; they provide facilities such as:
insert-composed-char
composing characters not found on the keyboard
match-words-by-style
configuring what the line editor considers a word when moving or deleting by word
history-beginning-search-backward-end
, etc.alternative ways of searching the shell history
replace-string
, replace-pattern
functions for replacing strings or patterns globally in the command line
edit-command-line
edit the command line with an external editor.
See ZLE Functions for descriptions of these.
The shell has a large number of options for changing its behaviour. These cover all aspects of the shell; browsing the full documentation is the only good way to become acquainted with the many possibilities. See Options.
The shell has a rich set of patterns which are available for file matching (described in the documentation as ‘filename generation’ and also known for historical reasons as ‘globbing’) and for use when programming. These are described in Filename Generation.
Of particular interest are the following patterns that are not commonly supported by other systems of pattern matching:
**
for matching over multiple directories
|
for matching either of two alternatives
~
, ^
the ability to exclude patterns from matching when the EXTENDED_GLOB
option is set
(
...)
glob qualifiers, included in parentheses at the end of the pattern, which select files by type (such as directories) or attribute (such as size).
Although the syntax of zsh is in ways similar to the Korn shell, and therefore more remotely to the original UNIX shell, the Bourne shell, its default behaviour does not entirely correspond to those shells. General shell syntax is introduced in Shell Grammar.
One commonly encountered difference is that variables substituted onto the
command line are not split into words. See the description of the shell option
SH_WORD_SPLIT
in
Parameter Expansion.
In zsh, you can either explicitly request the splitting (e.g. ${=foo}
)
or use an array when you want a variable to expand to more than one word. See
Array Parameters.
The most convenient way of adding enhancements to the shell is typically by writing a shell function and arranging for it to be autoloaded. Functions are described in Functions. Users changing from the C shell and its relatives should notice that aliases are less used in zsh as they don’t perform argument substitution, only simple text replacement.
A few general functions, other than those for the line editor described above, are provided with the shell and are described in User Contributions. Features include:
promptinit
a prompt theme system for changing prompts easily, see Prompt Themes
zsh-mime-setup
a MIME-handling system which dispatches commands according to the suffix of a file as done by graphical file managers
zcalc
a calculator
zargs
a version of xargs
that makes the find
command redundant
zmv
a command for renaming files by means of shell patterns.
The following flags are interpreted by the shell when invoked to determine where the shell will read commands from:
-c
Take the first argument as a command to execute, rather than reading commands
from a script or standard input. If any further arguments are given, the
first one is assigned to $0
, rather than being used as a positional
parameter.
-i
Force shell to be interactive. It is still possible to specify a script to execute.
-s
Force shell to read commands from the standard input.
If the -s
flag is not present and an argument is given,
the first argument is taken to be the pathname of a script to
execute.
If there are any remaining arguments after option processing, and neither
of the options -c
or -s
was supplied, the first argument is taken
as the file name of a script containing shell commands to be executed. If
the option PATH_SCRIPT
is set, and the file name does not contain a
directory path (i.e. there is no ‘/
’ in the name), first the current
directory and then the command path given by the variable PATH
are
searched for the script. If the option is not set or the file name
contains a ‘/
’ it is used directly.
After the first one or two arguments have been appropriated as described above, the remaining arguments are assigned to the positional parameters.
For further options, which are common to invocation and the set
builtin, see
Options.
The long option ‘-
-emulate
’ followed (in a separate word) by an
emulation mode may be passed to the shell.
The emulation modes are those described for the emulate
builtin,
see
Shell Builtin Commands.
The ‘-
-emulate
’ option must precede any other options (which might
otherwise be overridden), but following options are honoured, so
may be used to modify the requested emulation mode. Note that certain
extra steps are taken to ensure a smooth emulation when this option
is used compared with the emulate
command within the shell: for
example, variables that conflict with POSIX usage such as path
are
not defined within the shell.
Options may be specified by name using the -o
option. -o
acts like
a single-letter option, but takes a following string as the option name.
For example,
zsh -x -o shwordsplit scr
runs the script scr
, setting the XTRACE
option by the corresponding
letter ‘-x
’ and the SH_WORD_SPLIT
option by name.
Options may be turned off by name by using +o
instead of -o
.
-o
can be stacked up with preceding single-letter options, so for example
‘-xo shwordsplit
’ or ‘-xoshwordsplit
’ is equivalent to
‘-x -o shwordsplit
’.
Options may also be specified by name in GNU long option style,
‘-
-
option-name’. When this is done, ‘-
’ characters in the
option name are permitted: they are translated into ‘_
’, and thus ignored.
So, for example, ‘zsh -
-sh-word-split
’ invokes zsh with the
SH_WORD_SPLIT
option turned on. Like other option syntaxes, options can
be turned off by replacing the initial ‘-
’ with a ‘+
’; thus
‘+-sh-word-split
’ is equivalent to ‘-
-no-sh-word-split
’.
Unlike other option syntaxes, GNU-style long options cannot be stacked with
any other options, so for example ‘-x-shwordsplit
’ is an error,
rather than being treated like ‘-x -
-shwordsplit
’.
The special GNU-style option ‘-
-version
’ is handled; it sends to
standard output the shell’s version information, then exits successfully.
‘-
-help
’ is also handled; it sends to standard output a list of
options that can be used when invoking the shell, then exits successfully.
Option processing may be finished, allowing following arguments that start with
‘-
’ or ‘+
’ to be treated as normal arguments, in two ways.
Firstly, a lone ‘-
’ (or ‘+
’) as an argument by itself ends
option processing. Secondly, a special option ‘-
-
’ (or
‘+-
’), which may be specified on its own (which is the standard
POSIX usage) or may be stacked with preceding options (so ‘-x-
’ is
equivalent to ‘-x -
-
’). Options are not permitted to be stacked
after ‘-
-
’ (so ‘-x-f
’ is an error), but note the GNU-style
option form discussed above, where ‘-
-shwordsplit
’ is permitted
and does not end option processing.
Except when the sh/ksh emulation single-letter options are in effect,
the option ‘-b
’ (or ‘+b
’) ends option processing.
‘-b
’ is like ‘-
-
’, except that further single-letter options
can be stacked after the ‘-b
’ and will take effect as normal.
Zsh tries to emulate sh or ksh when it is invoked as
sh
or ksh
respectively; more precisely, it looks at the first
letter of the name by which it was invoked, excluding any initial ‘r
’
(assumed to stand for ‘restricted’), and if that is ‘b
’, ‘s
’ or ‘k
’ it
will emulate sh or ksh. Furthermore, if invoked as su
(which
happens on certain systems when the shell is executed by the su
command), the shell will try to find an alternative name from the SHELL
environment variable and perform emulation based on that.
In sh and ksh compatibility modes the following
parameters are not special and not initialized by the shell:
ARGC
,
argv
,
cdpath
,
fignore
,
fpath
,
HISTCHARS
,
mailpath
,
MANPATH
,
manpath
,
path
,
prompt
,
PROMPT
,
PROMPT2
,
PROMPT3
,
PROMPT4
,
psvar
,
status
.
The usual zsh startup/shutdown scripts are not executed. Login shells
source /etc/profile
followed by $HOME/.profile
. If the
ENV
environment variable is set on invocation, $ENV
is sourced
after the profile scripts. The value of ENV
is subjected to
parameter expansion, command substitution, and arithmetic expansion
before being interpreted as a pathname. Note that the PRIVILEGED
option also affects the execution of startup files.
The following options are set if the shell is invoked as sh
or
ksh
:
NO_BAD_PATTERN
,
NO_BANG_HIST
,
NO_BG_NICE
,
NO_EQUALS
,
NO_FUNCTION_ARGZERO
,
GLOB_SUBST
,
NO_GLOBAL_EXPORT
,
NO_HUP
,
INTERACTIVE_COMMENTS
,
KSH_ARRAYS
,
NO_MULTIOS
,
NO_NOMATCH
,
NO_NOTIFY
,
POSIX_BUILTINS
,
NO_PROMPT_PERCENT
,
RM_STAR_SILENT
,
SH_FILE_EXPANSION
,
SH_GLOB
,
SH_OPTION_LETTERS
,
SH_WORD_SPLIT
.
Additionally the BSD_ECHO
and IGNORE_BRACES
options are set if zsh is invoked as sh
.
Also, the
KSH_OPTION_PRINT
,
LOCAL_OPTIONS
,
PROMPT_BANG
,
PROMPT_SUBST
and
SINGLE_LINE_ZLE
options are set if zsh is invoked as ksh
.
Please note that, whilst reasonable efforts are taken to address
incompatibilities when they arise, zsh does not guarantee complete
emulation of other shells, nor POSIX compliance. For more information on
the differences between zsh and other shells, please refer to chapter 2
of the shell FAQ, https://www.zsh.org/FAQ/
.
When the basename of the command used to invoke zsh starts with the letter
‘r
’ or the ‘-r
’ command line option is supplied at invocation, the
shell becomes restricted. Emulation mode is determined after stripping the
letter ‘r
’ from the invocation name. The following are disabled in
restricted mode:
cd
builtin
EGID
, EUID
, GID
,
HISTFILE
, HISTSIZE
, IFS
, LD_AOUT_LIBRARY_PATH
,
LD_AOUT_PRELOAD
, LD_LIBRARY_PATH
, LD_PRELOAD
,
MODULE_PATH
, module_path
, PATH
, path
, SHELL
,
UID
and USERNAME
parameters
/
hash
exec
builtin command to replace the shell with another
command
jobs -Z
to overwrite the shell process’ argument and
environment space
ARGV0
parameter to override argv[0]
for external
commands
set +r
or unsetopt
RESTRICTED
These restrictions are enforced after processing the startup files. The
startup files should set up PATH
to point to a directory of commands
which can be safely invoked in the restricted environment. They may also
add further restrictions by disabling selected builtins.
Restricted mode can also be activated any time by setting the
RESTRICTED
option. This immediately enables all the restrictions
described above even if the shell still has not processed all startup
files.
A shell Restricted Mode is an outdated way to restrict what users may do: modern systems have better, safer and more reliable ways to confine user actions, such as chroot jails, containers and zones.
A restricted shell is very difficult to implement safely. The feature may be removed in a future version of zsh.
It is important to realise that the restrictions only apply to the shell,
not to the commands it runs (except for some shell builtins). While a
restricted shell can only run the restricted list of commands accessible
via the predefined ‘PATH
’ variable, it does not prevent those
commands from running any other command.
As an example, if ‘env
’ is among the list of allowed commands,
then it allows the user to run any command as ‘env
’ is not a shell
builtin command and can run arbitrary executables.
So when implementing a restricted shell framework it is important to be fully aware of what actions each of the allowed commands or features (which may be regarded as modules) can perform.
Many commands can have their behaviour affected by environment variables. Except for the few listed above, zsh does not restrict the setting of environment variables.
If a ‘perl
’, ‘python
’, ‘bash
’, or other general purpose
interpreted script it treated as a restricted
command, the user can work around the restriction by
setting specially crafted ‘PERL5LIB
’, ‘PYTHONPATH
’,
‘BASHENV
’ (etc.) environment variables. On GNU systems, any
command can be made to run arbitrary code when performing character set
conversion (including zsh itself) by setting a ‘GCONV_PATH
’
environment variable. Those are only a few examples.
Bear in mind that, contrary to some other shells, ‘readonly
’ is not a
security feature in zsh as it can be undone and so cannot be used to
mitigate the above.
A restricted shell only works if the allowed commands are few
and carefully written so as not to grant more access to users than
intended. It is also important to restrict what zsh module the user may
load as some of them, such as ‘zsh/system
’, ‘zsh/mapfile
’ and
‘zsh/files
’, allow bypassing most of the restrictions.
Commands are first read from /etc/zshenv
; this cannot be overridden.
Subsequent behaviour is modified by the RCS
and
GLOBAL_RCS
options; the former affects all startup files, while the
second only affects global startup files (those shown here with an
path starting with a /
). If one of the options
is unset at any point, any subsequent startup file(s)
of the corresponding
type will not be read. It is also possible for a file in $ZDOTDIR
to
re-enable GLOBAL_RCS
. Both RCS
and GLOBAL_RCS
are set by
default.
Commands are then read from $ZDOTDIR/.zshenv
.
If the shell is a login shell, commands
are read from /etc/zprofile
and then $ZDOTDIR/.zprofile
.
Then, if the shell is interactive,
commands are read from /etc/zshrc
and then $ZDOTDIR/.zshrc
.
Finally, if the shell is a login shell, /etc/zlogin
and
$ZDOTDIR/.zlogin
are read.
When a login shell exits, the files $ZDOTDIR/.zlogout
and then
/etc/zlogout
are read. This happens with either an explicit exit
via the exit
or logout
commands, or an implicit exit by reading
end-of-file from the terminal. However, if the shell terminates due
to exec
’ing another process, the logout files are not read.
These are also affected by the RCS
and GLOBAL_RCS
options.
Note also that the RCS
option affects the saving of history files,
i.e. if RCS
is unset when the shell exits, no history file will be
saved.
If ZDOTDIR
is unset, HOME
is used instead.
Files listed above as being in /etc
may be in another
directory, depending on the installation.
As /etc/zshenv
is run for all instances of zsh, it is important that
it be kept as small as possible. In particular, it is a good idea to
put code that does not need to be run for every single shell behind
a test of the form ‘if [[ -o rcs ]]; then ...
’ so that it will not
be executed when zsh is invoked with the ‘-f
’ option.
$ZDOTDIR/.zshenv
$ZDOTDIR/.zprofile
$ZDOTDIR/.zshrc
$ZDOTDIR/.zlogin
$ZDOTDIR/.zlogout
${TMPPREFIX}*
(default is /tmp/zsh*)/etc/zshenv
/etc/zprofile
/etc/zshrc
/etc/zlogin
/etc/zlogout
(installation-specific - /etc
is the default)Any of these files may be pre-compiled with the zcompile
builtin
command (Shell Builtin Commands). If a compiled file exists (named for the original file plus the
.zwc
extension) and it is newer than the original file, the compiled
file will be used instead.
A simple command is a sequence of optional parameter assignments followed by blank-separated words, with optional redirections interspersed. For a description of assignment, see the beginning of Parameters.
The first word is the command to be executed, and the remaining words, if any, are arguments to the command. If a command name is given, the parameter assignments modify the environment of the command when it is executed. The value of a simple command is its exit status, or 128 plus the signal number if terminated by a signal. For example,
echo foo
is a simple command with arguments.
A pipeline is either a simple command, or a sequence of two or more
simple commands where each command is separated from the next by ‘|
’
or ‘|&
’. Where commands are separated by ‘|
’, the standard
output of the first command is connected to the
standard input of the next. ‘|&
’ is shorthand for ‘2>&1 |
’, which
connects both the standard output and the standard error of the
command to the standard input of the next. The value of a pipeline
is the value of the last command, unless the pipeline is preceded by
‘!
’ in which case the value is the logical inverse of the value of the
last command.
For example,
echo foo | sed 's/foo/bar/'
is a pipeline, where the output (‘foo
’ plus a newline) of the first
command will be passed to the input of the second.
If a pipeline is preceded by ‘coproc
’, it is executed as a coprocess;
a two-way pipe is established between it and the parent shell. The
shell can read from or write to the coprocess by means of the ‘>&p
’
and ‘<&p
’ redirection operators or with ‘print -p
’ and ‘read -p
’.
A pipeline cannot be preceded by both ‘coproc
’ and ‘!
’.
If job control is active, the coprocess can be treated in other than input
and output as an ordinary background job.
A sublist is either a single pipeline, or a sequence of two or more
pipelines separated by ‘&&
’ or ‘||
’. If two pipelines are separated
by ‘&&
’, the second pipeline is executed only if the first succeeds
(returns a zero status). If two pipelines are separated by ‘||
’, the
second is executed only if the first fails (returns a nonzero status).
Both operators have equal precedence and are left associative.
The value of the sublist is the value of the last pipeline executed.
For example,
dmesg | grep panic && print yes
is a sublist consisting of two pipelines, the second just a simple command
which will be executed if and only if the grep
command returns a zero
status. If it does not, the value of the sublist is that return status, else
it is the status returned by the print
(almost certainly zero).
A list is a sequence of zero or more sublists, in which each sublist
is terminated by ‘;
’, ‘&
’, ‘&|
’, ‘&!
’, or a newline.
This terminator
may optionally be omitted from the last sublist in the list when the
list appears as a complex command inside ‘(
...)
’
or ‘{
...}
’. When a
sublist is terminated by ‘;
’ or newline, the shell waits for it to
finish before executing the next sublist. If a sublist is terminated
by a ‘&
’, ‘&|
’, or ‘&!
’,
the shell executes the last pipeline in it in the background, and
does not wait for it to finish (note the difference from other shells
which execute the whole sublist in the background).
A backgrounded pipeline returns a status of zero.
More generally, a list can be seen as a set of any shell commands whatsoever, including the complex commands below; this is implied wherever the word ‘list’ appears in later descriptions. For example, the commands in a shell function form a special sort of list.
A simple command may be preceded by a precommand modifier,
which will alter how the command is interpreted. These modifiers are
shell builtin commands with the exception of nocorrect
which is
a reserved word.
-
¶The command is executed with a ‘-
’ prepended to its
argv[0]
string.
builtin
¶The command word is taken to be the name of a builtin command, rather than a shell function or external command.
command
[ -pvV
] ¶The command word is taken to be the name of an external command,
rather than a shell function or builtin. If the POSIX_BUILTINS
option
is set, builtins will also be executed but certain special properties
of them are suppressed. The -p
flag causes a default path to be
searched instead of that in $path
. With the -v
flag, command
is similar to whence
and with -V
, it is equivalent to whence
-v
.
exec
[ -cl
] [ -a
argv0 ] ¶The following command together with any arguments is run in place
of the current process, rather than as a sub-process. The shell does not
fork and is replaced. The shell does not invoke TRAPEXIT
, nor does it
source zlogout
files.
The options are provided for compatibility with other shells.
The -c
option clears the environment.
The -l
option is equivalent to the -
precommand modifier, to
treat the replacement command as a login shell; the command is executed
with a -
prepended to its argv[0]
string. This flag has no effect
if used together with the -a
option.
The -a
option is used to specify explicitly the argv[0]
string
(the name of the command as seen by the process itself) to be used by the
replacement command and is directly equivalent to setting a value
for the ARGV0
environment variable.
nocorrect
¶Spelling correction is not done on any of the words. This must appear before any other precommand modifier, as it is interpreted immediately, before any parsing is done. It has no effect in non-interactive shells.
noglob
¶Filename generation (globbing) is not performed on any of the words.
A complex command in zsh is one of the following:
if
list then
list [ elif
list then
list ] ... [ else
list ] fi
¶The if
list is executed, and if it returns a zero exit status,
the then
list is executed.
Otherwise, the elif
list is executed and if its status is zero,
the then
list is executed.
If each elif
list returns nonzero status, the else
list
is executed.
for
name ... [ in
word ... ] term do
list done
¶Expand the list of words, and set the parameter
name to each of them in turn, executing list
each time. If the ‘in
word’ is omitted,
use the positional parameters instead of the words.
The term consists of one or more newline or ;
which terminate the words, and are optional when the
‘in
word’ is omitted.
More than one parameter name can appear before the list of
words. If N names are given, then on each execution of the
loop the next N words are assigned to the corresponding
parameters. If there are more names than remaining words, the
remaining parameters are each set to the empty string. Execution of the
loop ends when there is no remaining word to assign to the first
name. It is only possible for in
to appear as the first name
in the list, else it will be treated as marking the end of the list.
for ((
[expr1] ;
[expr2] ;
[expr3] )) do
list done
The arithmetic expression expr1 is evaluated first (see Arithmetic Evaluation). The arithmetic expression expr2 is repeatedly evaluated until it evaluates to zero and when non-zero, list is executed and the arithmetic expression expr3 evaluated. If any expression is omitted, then it behaves as if it evaluated to 1.
while
list do
list done
¶Execute the do
list as long as the while
list
returns a zero exit status.
until
list do
list done
¶Execute the do
list as long as until
list
returns a nonzero exit status.
repeat
word do
list done
¶word is expanded and treated as an arithmetic expression, which must evaluate to a number n. list is then executed n times.
The repeat
syntax is disabled by default when the
shell starts in a mode emulating another shell. It can be enabled
with the command ‘enable -r repeat
’
case
word in
[ [(
] pattern [ |
pattern ] ... )
list (;;
|;&
|;|
) ] ... esac
¶Execute the list associated with the first pattern that matches word, if any. The form of the patterns is the same as that used for filename generation. See Filename Generation.
Note further that, unless the SH_GLOB
option is set, the whole
pattern with alternatives is treated by the shell as equivalent to a
group of patterns within parentheses, although white space may appear
about the parentheses and the vertical bar and will be stripped from the
pattern at those points. White space may appear elsewhere in the
pattern; this is not stripped. If the SH_GLOB
option is set, so
that an opening parenthesis can be unambiguously treated as part of the
case syntax, the expression is parsed into separate words and these are
treated as strict alternatives (as in other shells).
If the list that is executed is terminated with ;&
rather than
;;
, the following list is also executed. The rule for
the terminator of the following list ;;
, ;&
or ;|
is
applied unless the esac
is reached.
If the list that is executed is terminated with ;|
the
shell continues to scan the patterns looking for the next match,
executing the corresponding list, and applying the rule for
the corresponding terminator ;;
, ;&
or ;|
.
Note that word is not re-expanded; all applicable patterns
are tested with the same word.
select
name [ in
word ... term ] do
list done
¶where term is one or more newline or ;
to terminate the words.
Print the set of words, each preceded by a number.
If the in
word is omitted, use the positional parameters.
The PROMPT3
prompt is printed and a line is read from the line editor
if the shell is interactive and that is active, or else standard input.
If this line consists of the
number of one of the listed words, then the parameter name
is set to the word corresponding to this number.
If this line is empty, the selection list is printed again.
Otherwise, the value of the parameter name is set to null.
The contents of the line read from standard input is saved
in the parameter REPLY
. list is executed
for each selection until a break or end-of-file is encountered.
(
list )
¶Execute list in a subshell. Traps set by the trap
builtin
are reset to their default values while executing list; an
exception is that ignored signals will continue to be ignored
if the option POSIXTRAPS
is set.
{
list }
Execute list.
{
try-list } always {
always-list }
¶First execute try-list. Regardless of errors, or break
or
continue
commands encountered within try-list,
execute always-list. Execution then continues from the
result of the execution of try-list; in other words, any error,
or break
or continue
command is treated in the
normal way, as if always-list were not present. The two
chunks of code are referred to as the ‘try block’ and the ‘always block’.
Optional newlines or semicolons may appear after the always
;
note, however, that they may not appear between the preceding
closing brace and the always
.
An ‘error’ in this context is a condition such as a syntax error which
causes the shell to abort execution of the current function, script, or
list. Syntax errors encountered while the shell is parsing the
code do not cause the always-list to be executed. For example,
an erroneously constructed if
block in try-list would cause the
shell to abort during parsing, so that always-list would not be
executed, while an erroneous substitution such as ${*foo*}
would
cause a run-time error, after which always-list would be executed.
An error condition can be tested and reset with the special integer
variable TRY_BLOCK_ERROR
. Outside an always-list the value is
irrelevant, but it is initialised to -1
. Inside always-list, the
value is 1 if an error occurred in the try-list, else 0. If
TRY_BLOCK_ERROR
is set to 0 during the always-list, the error
condition caused by the try-list is reset, and shell execution
continues normally after the end of always-list. Altering the value
during the try-list is not useful (unless this forms part of an
enclosing always
block).
Regardless of TRY_BLOCK_ERROR
, after the end of always-list the
normal shell status $?
is the value returned from try-list.
This will be non-zero if there was an error, even if TRY_BLOCK_ERROR
was set to zero.
The following executes the given code, ignoring any errors it causes. This is an alternative to the usual convention of protecting code by executing it in a subshell.
{ # code which may cause an error } always { # This code is executed regardless of the error. (( TRY_BLOCK_ERROR = 0 )) } # The error condition has been reset.
When a try
block occurs outside of any function,
a return
or a exit
encountered in try-list does not cause
the execution of always-list. Instead, the shell exits immediately
after any EXIT
trap has been executed.
Otherwise, a return
command encountered in try-list will cause the
execution of always-list, just like break
and continue
.
function
[ -T
] word ... [ ()
] [ term ] {
list }
¶()
[ term ] {
list }
()
[ term ] commandwhere term is one or more newline or ;
.
Define a function which is referenced by any one of word.
Normally, only one word is provided; multiple words
are usually only useful for setting traps.
The body of the function is the list between
the {
and }
. See Functions.
The options of function
have the following meanings:
Enable tracing for this function, as though with functions -T
. See the
documentation of the -f
option to the typeset
builtin, in
Shell Builtin Commands.
If the option SH_GLOB
is set for compatibility with other shells, then
whitespace may appear between the left and right parentheses when
there is a single word; otherwise, the parentheses will be treated as
forming a globbing pattern in that case.
In any of the forms above, a redirection may appear outside the function body, for example
func() { ... } 2>&1
The redirection is stored with the function and applied whenever the function is executed. Any variables in the redirection are expanded at the point the function is executed, but outside the function scope.
time
[ pipeline ] ¶The pipeline is executed, and timing statistics are
reported on the standard error in the form specified
by the TIMEFMT
parameter.
If pipeline is omitted, print statistics about the
shell process and its children.
[[
exp ]]
¶Evaluates the conditional expression exp and return a zero exit status if it is true. See Conditional Expressions for a description of exp.
Many of zsh’s complex commands have alternate forms. These are non-standard and are likely not to be obvious even to seasoned shell programmers; they should not be used anywhere that portability of shell code is a concern.
The short versions below only work if sublist is of the form ‘{
list }
’ or if the SHORT_LOOPS
option is set. For the if
,
while
and until
commands, in both these cases the test part of the
loop must also be suitably delimited, such as by ‘[[
... ]]
’ or
‘((
... ))
’,
else the end of the test will not be recognized. For the
for
, repeat
, case
and select
commands no such special form
for the arguments is necessary, but the other condition (the special form
of sublist or use of the SHORT_LOOPS
option) still applies.
The SHORT_REPEAT
option is available to enable the short version only
for the repeat
command.
if
list {
list }
[ elif
list {
list }
] ... [ else {
list }
]An alternate form of if
. The rules mean that
if [[ -o ignorebraces ]] { print yes }
works, but
if true { # Does not work! print yes }
does not, since the test is not suitably delimited.
if
list sublistA short form of the alternate if
. The same limitations on the form of
list apply as for the previous form.
for
name ... (
word ... )
sublistA short form of for
.
for
name ... [ in
word ... ] term sublistwhere term is at least one newline or ;
.
Another short form of for
.
for ((
[expr1] ;
[expr2] ;
[expr3] ))
sublistA short form of the arithmetic for
command.
foreach
name ... (
word ... )
list end
¶Another form of for
.
while
list {
list }
An alternative form of while
. Note the limitations on the form of
list mentioned above.
until
list {
list }
An alternative form of until
. Note the limitations on the form of
list mentioned above.
repeat
word sublistThis is a short form of repeat
.
case
word {
[ [(
] pattern [ |
pattern ] ... )
list (;;
|;&
|;|
) ] ... }
An alternative form of case
.
select
name [ in
word ... term ] sublistwhere term is at least one newline or ;
.
A short form of select
.
function
word ... [ ()
] [ term ] sublistThis is a short form of function
.
The following words are recognized as reserved words when used as the first
word of a command unless quoted or disabled using disable -r
:
do done esac then elif else fi for case
if while function repeat time until
select coproc nocorrect foreach end ! [[ { }
declare export float integer local readonly typeset
Additionally, ‘}
’ is recognized in any position if neither the
IGNORE_BRACES
option nor the IGNORE_CLOSE_BRACES
option is set.
Certain errors are treated as fatal by the shell: in an interactive
shell, they cause control to return to the command line, and in a
non-interactive shell they cause the shell to be aborted. In older
versions of zsh, a non-interactive shell running a script would not
abort completely, but would resume execution at the next command to be
read from the script, skipping the remainder of any functions or
shell constructs such as loops or conditions; this somewhat illogical
behaviour can be recovered by setting the option CONTINUE_ON_ERROR
.
Fatal errors found in non-interactive shells include:
set
builtin
typeset
,
local
, declare
, export
, integer
, float
continue
, break
)
RESTRICTED
options is set
BAD_PATTERN
NO_MATCH
or
similar options
$'
...'
expressions
If the POSIX_BUILTINS
option is set, more errors associated with
shell builtin commands are treated as fatal, as specified by the POSIX
standard.
In non-interactive shells, or in interactive shells with the
INTERACTIVE_COMMENTS
option set, a word beginning
with the third character of the histchars
parameter
(‘#
’ by default) causes that word and all the following
characters up to a newline to be ignored.
Every eligible word in the shell input is checked to see if there is an alias defined for it. If so, it is replaced by the text of the alias if it is in command position (if it could be the first word of a simple command), or if the alias is global. If the replacement text ends with a space, the next word in the shell input is always eligible for purposes of alias expansion.
It is an error for the function name, word, in the sh-compatible function
definition syntax ‘word ()
...’ to be a word that resulted
from alias expansion, unless the ALIAS_FUNC_DEF
option is set.
An alias is defined using the alias
builtin; global aliases
may be defined using the -g
option to that builtin.
A word is defined as:
case
, do
, else
, etc.)
(
’ or ‘)
’ when not part of a glob pattern
Alias expansion is done on the shell input before any other expansion
except history expansion. Therefore, if an alias is defined for the
word foo
, alias expansion may be avoided by quoting part of the
word, e.g. \foo
. Any form of quoting works, although there is
nothing to prevent an alias being defined for the quoted form such as
\foo
as well.
In particular, note that quoting must be used when using unalias
to remove
global aliases:
% alias -g foo=bar % unalias foo unalias: no such hash table element: bar % unalias \foo %
When POSIX_ALIASES
is set, only plain unquoted strings are eligible
for aliasing. The alias
builtin does not reject ineligible aliases,
but they are not expanded.
For use with completion, which would remove an initial backslash followed
by a character that isn’t special, it may be more convenient to quote the
word by starting with a single quote, i.e. 'foo
; completion will
automatically add the trailing single quote.
Although aliases can be used in ways that bend normal shell syntax, not every string of non-white-space characters can be used as an alias.
Any set of characters not listed as a word above is not a word, hence no
attempt is made to expand it as an alias, no matter how it is defined
(i.e. via the builtin or the special parameter aliases
described in
The zsh/parameter Module).
However, as noted in the case of POSIX_ALIASES
above, the shell does
not attempt to deduce whether the string corresponds to a word at the
time the alias is created.
For example, an expression containing an =
at the start of
a command line is an assignment and cannot be expanded as an alias;
a lone =
is not an assignment but can only be set as an alias
using the parameter, as otherwise the =
is taken part of the
syntax of the builtin command.
It is not presently possible to alias the ‘((
’ token that
introduces arithmetic expressions, because until a full statement has been
parsed, it cannot be distinguished from two consecutive ‘(
’
tokens introducing nested subshells.
Also, if a separator such as &&
is aliased,
\&&
turns into the two tokens \&
and &
, each of which may
have been aliased separately. Similarly for \<<
, \>|
, etc.
There is a commonly encountered problem with aliases illustrated by the following code:
alias echobar='echo bar'; echobar
This prints a message that the command echobar
could not be found.
This happens because aliases are expanded when the code is read in;
the entire line is read in one go, so that when echobar
is executed it
is too late to expand the newly defined alias. This is often
a problem in shell scripts, functions, and code executed with ‘source
’
or ‘.
’. Consequently, use of functions rather than aliases is
recommended in non-interactive code.
A character may be quoted (that is, made
to stand for itself) by preceding it with a ‘\
’.
‘\
’ followed by a newline is ignored.
A string enclosed between ‘$'
’ and ‘'
’ is
processed the same way as the string arguments of the
print
builtin, and the resulting string is considered to be
entirely quoted. A literal ‘'
’ character can be included in the
string by using the ‘\'
’ escape.
All characters enclosed between a pair of single quotes ({No value for `dsq'}
) that
is not preceded by a ‘$
’ are quoted. A single quote cannot appear
within single quotes unless the option RC_QUOTES
is set, in which case
a pair of single quotes are turned into a single quote. For example,
print {No value for `dsq'}{No value for `dsq'}
outputs nothing apart from a newline if RC_QUOTES
is not set, but one
single quote if it is set.
Inside double quotes (""
), parameter and
command substitution occur, and ‘\
’ quotes the characters
‘\
’, ‘`
’, ‘"
’, ‘$
’, and the first character
of $histchars
(default ‘!
’).
If a command is followed by &
and job control is not active,
then the default standard input
for the command is the empty file /dev/null
.
Otherwise, the environment for the execution of a command contains the
file descriptors of the invoking shell as modified by
input/output specifications.
The following may appear anywhere in a simple command or may precede or follow a complex command. Expansion occurs before word or digit is used except as noted below. If the result of substitution on word produces more than one filename, redirection occurs for each separate filename in turn.
<
wordOpen file word for reading as standard input. It is an error to open a file in this fashion if it does not exist.
<>
wordOpen file word for reading and writing as standard input. If the file does not exist then it is created.
>
wordOpen file word for writing as standard output.
If the file does not exist then it is created.
If the file exists, and the CLOBBER
option is unset,
this causes an error;
otherwise, it is truncated to zero length.
>|
word>!
wordSame as >
, except that the file is truncated to zero length
if it exists, regardless of CLOBBER
.
>>
wordOpen file word for writing in append mode as standard output.
If the file does not exist, and the CLOBBER
and APPEND_CREATE
options are both unset, this causes an error;
otherwise, the file is created.
>>|
word>>!
wordSame as >>
, except that the file is created if it does not
exist, regardless of CLOBBER
and APPEND_CREATE
.
<<
[-
] wordThe shell input is read up to a line that is the same as word, or to an end-of-file. No parameter expansion, command substitution or filename generation is performed on word. The resulting document, called a here-document, becomes the standard input.
If any character of word is quoted with
single or double quotes or a ‘\
’,
no interpretation is placed upon the characters of the document.
Otherwise, parameter and command substitution
occurs, ‘\
’ followed by a newline is removed,
and ‘\
’ must be used to quote the characters
‘\
’, ‘$
’, ‘`
’ and the first character of word.
Note that word itself does not undergo shell expansion. Backquotes
in word do not have their usual effect; instead they behave
similarly to double quotes, except that the backquotes themselves are
passed through unchanged. (This information is given for completeness
and it is not recommended that backquotes be used.) Quotes in the form
$'
...'
have their standard effect of expanding backslashed
references to special characters.
If <<-
is used, then all leading
tabs are stripped from word and from the document.
<<<
wordPerform shell expansion on word and pass the result to standard input. This is known as a here-string. Compare the use of word in here-documents above, where word does not undergo shell expansion. The result will have a trailing newline after it.
<&
number>&
numberThe standard input/output is duplicated from file descriptor number (see dup2(2)).
<& -
>& -
Close the standard input/output.
<& p
>& p
The input/output from/to the coprocess is moved to the standard input/output.
>&
word&>
word(Except where ‘>&
word’ matches one of the above syntaxes;
‘&>
’ can always be used to avoid this ambiguity.)
Redirects both standard output and standard error (file descriptor 2)
in the manner of ‘>
word’.
Note that this does not have the same effect as ‘>
word 2>&1
’
in the presence of multios (see the section below).
>&|
word>&!
word&>|
word&>!
wordRedirects both standard output and standard error (file descriptor 2)
in the manner of ‘>|
word’.
>>&
word&>>
wordRedirects both standard output and standard error (file descriptor 2)
in the manner of ‘>>
word’.
>>&|
word>>&!
word&>>|
word&>>!
wordRedirects both standard output and standard error (file descriptor 2)
in the manner of ‘>>|
word’.
If one of the above is preceded by a digit, then the file descriptor referred to is that specified by the digit instead of the default 0 or 1. The order in which redirections are specified is significant. The shell evaluates each redirection in terms of the (file descriptor, file) association at the time of evaluation. For example:
...
1>
fname2>&1
first associates file descriptor 1 with file fname. It then associates file descriptor 2 with the file associated with file descriptor 1 (that is, fname). If the order of redirections were reversed, file descriptor 2 would be associated with the terminal (assuming file descriptor 1 had been) and then file descriptor 1 would be associated with file fname.
The ‘|&
’ command separator described in
Simple Commands & Pipelines
is a shorthand for ‘2>&1 |
’.
The various forms of process substitution, ‘<(
list)
’,
and ‘=(
list)
’ for input and
‘>(
list)
’ for output, are often used together with
redirection. For example, if word in an output redirection is of the
form ‘>(
list)
’ then the output is piped to the
command represented by list. See
Process Substitution.
When the shell is parsing arguments to a command, and the shell option
IGNORE_BRACES
is not set, a different form of redirection is allowed:
instead of a digit before the operator there is a valid shell identifier
enclosed in braces. The shell will open a new file descriptor that
is guaranteed to be at least 10 and set the parameter named by the
identifier to the file descriptor opened. No whitespace is allowed
between the closing brace and the redirection character. For example:
...
{myfd}>&1
This opens a new file descriptor that is a duplicate of file descriptor
1 and sets the parameter myfd
to the number of the file descriptor,
which will be at least 10. The new file descriptor can be written to using
the syntax >&$myfd
. The file descriptor remains open in subshells
and forked external executables.
The syntax {
varid}>&-
, for example {myfd}>&-
, may be used
to close a file descriptor opened in this fashion. Note that the
parameter given by varid must previously be set to a file descriptor
in this case.
It is an error to open or close a file descriptor in this fashion when the
parameter is readonly. However, it is not an error to read or write a file
descriptor using <&$
param or >&$
param if param is
readonly.
If the option CLOBBER
is unset, it is an error to open a file
descriptor using a parameter that is already set to an open file descriptor
previously allocated by this mechanism. Unsetting the parameter before
using it for allocating a file descriptor avoids the error.
Note that this mechanism merely allocates or closes a file descriptor; it
does not perform any redirections from or to it. It is usually convenient
to allocate a file descriptor prior to use as an argument to exec
.
The syntax does not in any case work when used around complex commands
such as parenthesised subshells or loops, where the opening brace is
interpreted as part of a command list to be executed in the current shell.
The following shows a typical sequence of allocation, use, and closing of a file descriptor:
integer myfd exec {myfd}>~/logs/mylogfile.txt print This is a log message. >&$myfd exec {myfd}>&-
Note that the expansion of the variable in the expression >&$myfd
occurs at the point the redirection is opened. This is after the expansion
of command arguments and after any redirections to the left on the command
line have been processed.
If the user tries to open a file descriptor for writing more than once,
the shell opens the file descriptor as a pipe to a process that copies
its input to all the specified outputs, similar to tee,
provided the MULTIOS
option is set, as it is by default. Thus:
date >foo >bar
writes the date to two files, named ‘foo
’ and ‘bar
’.
Note that a pipe is an implicit redirection; thus
date >foo | cat
writes the date to the file ‘foo
’, and also pipes it to cat.
Note that the shell opens all the files to be used in the multio process immediately, not at the point they are about to be written.
Note also that redirections are always expanded in order. This happens
regardless of the setting of the MULTIOS
option, but with the option
in effect there are additional consequences. For example,
the meaning of the expression >&1
will change after a previous
redirection:
date >&1 >output
In the case above, the >&1
refers to the standard output at the
start of the line; the result is similar to the tee
command.
However, consider:
date >output >&1
As redirections are evaluated in order, when the >&1
is encountered
the standard output is set to the file output
and another copy of
the output is therefore sent to that file. This is unlikely to be what
is intended.
If the MULTIOS
option is set, the word after a redirection operator is also subjected
to filename generation (globbing). Thus
: > *
will truncate all files in the current directory,
assuming there’s at least one. (Without the MULTIOS
option, it would create an empty file called ‘*
’.)
Similarly, you can do
echo exit 0 >> *.sh
If the user tries to open a file descriptor for reading more than once,
the shell opens the file descriptor as a pipe to a process that copies
all the specified inputs to its output in the order specified, provided
the MULTIOS
option is set. It should be noted that each file is
opened immediately, not at the point where it is about to be read:
this behaviour differs from cat
, so if strictly standard behaviour
is needed, cat
should be used instead.
Thus
sort <foo <fubar
or even
sort <f{oo,ubar}
is equivalent to ‘cat foo fubar | sort
’.
Expansion of the redirection argument occurs at the point the redirection
is opened, at the point described above for the expansion of the variable
in >&$myfd
.
Note that a pipe is an implicit redirection; thus
cat bar | sort <foo
is equivalent to ‘cat bar foo | sort
’ (note the order of the inputs).
If the MULTIOS
option is unset,
each redirection replaces the previous redirection for that file descriptor.
However, all files redirected to are actually opened, so
echo Hello > bar > baz
when MULTIOS
is unset will truncate ‘bar
’, and write ‘Hello
’
into ‘baz
’.
There is a problem when an output multio is attached to an external program. A simple example shows this:
cat file >file1 >file2 cat file1 file2
Here, it is possible that the second ‘cat
’ will not display the full
contents of file1
and file2
(i.e. the original contents of
file
repeated twice).
The reason for this is that the multios are spawned after the cat
process is forked from the parent shell, so the parent shell does not
wait for the multios to finish writing data. This means the command as
shown can exit before file1
and file2
are completely written.
As a workaround, it is possible to run the cat
process as part of a
job in the current shell:
{ cat file } >file >file2
Here, the {
...}
job will pause to wait for both files to be
written.
When a simple command consists of one or more redirection operators and zero or more parameter assignments, but no command name, zsh can behave in several ways.
If the parameter NULLCMD
is not set or the option CSH_NULLCMD
is
set, an error is caused. This is the csh behavior and CSH_NULLCMD
is set by default when emulating csh.
If the option SH_NULLCMD
is set, the builtin ‘:
’ is inserted as a
command with the given redirections. This is the default when emulating
sh or ksh.
Otherwise, if the parameter NULLCMD
is set, its value will be used as a
command with the given redirections. If both NULLCMD
and
READNULLCMD
are set, then the value of the latter will be used instead
of that of the former when the redirection is an input. The default for
NULLCMD
is ‘cat
’ and for READNULLCMD
is ‘more
’. Thus
< file
shows the contents of file
on standard output, with paging if that is a
terminal. NULLCMD
and READNULLCMD
may refer to shell functions.
If a command name contains no slashes, the shell attempts to locate it. If there exists a shell function by that name, the function is invoked as described in Functions. If there exists a shell builtin by that name, the builtin is invoked.
Otherwise, the shell searches each element of $path
for a
directory containing an executable file by that name.
If execution fails: an error message is printed, and one of the following values is returned.
The search was unsuccessful. The error message is
‘command not found:
cmd’.
The executable file has insufficient permissions, is a directory or special file, or is not a script and is in a format unrecognized by the operating system. The exact conditions and error message are operating system-dependent; see execve(2).
If execution fails because the file is not in executable format,
and the file is not a directory, it is assumed to be a shell
script. /bin/sh
is spawned to execute it. If the program
is a file beginning with ‘#!
’, the remainder of the first line
specifies an interpreter for the program. The shell will
execute the specified interpreter on operating systems that do
not handle this executable format in the kernel.
If no external command is found but a function command_not_found_handler
exists the shell executes this function with all
command line arguments. The return status of the function becomes the
status of the command. Note that the handler is executed in a
subshell forked to execute an external command, hence changes to
directories, shell parameters, etc. have no effect on the main shell.
Shell functions are defined with the function
reserved word or the
special syntax ‘funcname ()
’.
Shell functions are read in and stored internally.
Alias names are resolved when the function is read.
Functions are executed like commands with the arguments
passed as positional parameters.
(See Command Execution.)
Functions execute in the same process as the caller and
share all files
and present working directory with the
caller. A trap on EXIT
set inside a function
is executed after the function completes in the environment
of the caller.
The return
builtin is used to return from function calls.
Function identifiers can be listed with the functions
builtin.
Functions can be undefined with the unfunction
builtin.
A function can be marked as undefined using the autoload
builtin
(or ‘functions -u
’ or ‘typeset -fu
’). Such a function has no
body. When the function is first executed, the shell searches for its
definition using the elements of the fpath
variable. Thus to define
functions for autoloading, a typical sequence is:
fpath=(~/myfuncs $fpath) autoload myfunc1 myfunc2 ...
The usual alias expansion during reading will be suppressed if the
autoload
builtin or its equivalent is given the option -U
. This is
recommended for the use of functions supplied with the zsh distribution.
Note that for functions precompiled with the zcompile
builtin command
the flag -U
must be provided when the .zwc
file is created, as the
corresponding information is compiled into the latter.
For each element in fpath
, the shell looks for three possible
files, the newest of which is used to load the definition for the function:
.zwc
A file created with the zcompile
builtin command, which is expected to
contain the definitions for all functions in the directory named
element. The file is treated in the same manner as a directory
containing files for functions and is searched for the definition of the
function. If the definition is not found, the search for a definition
proceeds with the other two possibilities described below.
If element already includes a .zwc
extension (i.e. the extension
was explicitly given by the user), element is searched for the
definition of the function without comparing its age to that of other
files; in fact, there does not need to be any directory named element
without the suffix. Thus including an element such as
‘/usr/local/funcs.zwc
’ in fpath
will speed up the search for
functions, with the disadvantage that functions included must be explicitly
recompiled by hand before the shell notices any changes.
/
function.zwc
A file created with zcompile
, which is expected to contain the
definition for function. It may include other function definitions
as well, but those are neither loaded nor executed; a file found in this
way is searched only for the definition of function.
/
functionA file of zsh command text, taken to be the definition for function.
In summary, the order of searching is, first, in the parents of
directories in fpath
for the newer of either a compiled directory or
a directory in fpath
; second, if more than one of these contains a
definition for the function that is sought, the leftmost in the fpath
is chosen; and third, within a directory, the newer of either a compiled
function or an ordinary function definition is used.
If the KSH_AUTOLOAD
option is set, or the file contains only a
simple definition of the function, the file’s contents will be executed.
This will normally define the function in question, but may also perform
initialization, which is executed in the context of the function execution,
and may therefore define local parameters. It is an error if the function
is not defined by loading the file.
Otherwise, the function body (with no surrounding ‘funcname()
{
...}
’) is taken to be the complete contents of the file. This
form allows the file to be used directly as an executable shell script. If
processing of the file results in the function being re-defined, the
function itself is not re-executed. To force the shell to perform
initialization and then call the function defined, the file should contain
initialization code (which will be executed then discarded) in addition to
a complete function definition (which will be retained for subsequent calls
to the function), and a call to the shell function, including any
arguments, at the end.
For example, suppose the autoload file func
contains
func() { print This is func; } print func is initialized
then ‘func; func
’ with KSH_AUTOLOAD
set will produce both messages
on the first call, but only the message ‘This is func
’ on the second
and subsequent calls. Without KSH_AUTOLOAD
set, it will produce
the initialization message on the first call, and the other message on the
second and subsequent calls.
It is also possible to create a function that is not marked as autoloaded,
but which loads its own definition by searching fpath
, by using
‘autoload -X
’ within a shell function. For example, the following are
equivalent:
myfunc() { autoload -X } myfunc args...
and
unfunction myfunc # if myfunc was defined autoload myfunc myfunc args...
In fact, the functions
command outputs ‘builtin autoload -X
’ as
the body of an autoloaded function. This is done so that
eval "$(functions)"
produces a reasonable result. A true autoloaded function can be
identified by the presence of the comment ‘# undefined
’ in the body,
because all comments are discarded from defined functions.
To load the definition of an autoloaded function myfunc
without
executing myfunc
, use:
autoload +X myfunc
If no name is given for a function, it is ‘anonymous’ and is handled
specially. Either form of function definition may be used: a ‘()
’ with
no preceding name, or a ‘function
’ with an immediately following open
brace. The function is executed immediately at the point of definition and
is not stored for future use. The function name is set to ‘(anon)
’.
Arguments to the function may be specified as words following the
closing brace defining the function, hence if there are none no
arguments (other than $0
) are set. This is a difference from the
way other functions are parsed: normal function definitions may be
followed by certain keywords such as ‘else
’ or ‘fi
’, which will
be treated as arguments to anonymous functions, so that a newline or
semicolon is needed to force keyword interpretation.
Note also that the argument list of any enclosing script or function is hidden (as would be the case for any other function called at this point).
Redirections may be applied to the anonymous function in the same manner as to a current-shell structure enclosed in braces. The main use of anonymous functions is to provide a scope for local variables. This is particularly convenient in start-up files as these do not provide their own local variable scope.
For example,
variable=outside function { local variable=inside print "I am $variable with arguments $*" } this and that print "I am $variable"
outputs the following:
I am inside with arguments this and that I am outside
Note that function definitions with arguments that expand to nothing,
for example ‘name=; function $name {
... }
’, are not
treated as anonymous functions. Instead, they are treated as normal
function definitions where the definition is silently discarded.
Certain functions, if defined, have special meaning to the shell.
For the functions below, it is possible to define an array that has the
same name as the function with ‘_functions
’ appended. Any element in
such an array is taken as the name of a function to execute; it is executed
in the same context and with the same arguments and same initial value of $?
as the basic function. For
example, if $chpwd_functions
is an array containing the values
‘mychpwd
’, ‘chpwd_save_dirstack
’, then the shell attempts to
execute the functions ‘chpwd
’, ‘mychpwd
’ and
‘chpwd_save_dirstack
’, in that order. Any function that does not exist
is silently ignored. A function found by this mechanism is referred to
elsewhere as a hook function. An error in any function causes subsequent
functions not to be run. Note further that an error in a precmd
hook
causes an immediately following periodic
function not to run (though
it may run at the next opportunity).
chpwd
¶Executed whenever the current working directory is changed.
periodic
¶If the parameter PERIOD
is set, this function is executed every $PERIOD
seconds, just before a prompt. Note that if multiple functions
are defined using the array periodic_functions
only one
period is applied to the complete set of functions, and the
scheduled time is not reset if the list of functions is altered.
Hence the set of functions is always called together.
precmd
¶Executed before each prompt. Note that precommand functions are not re-executed simply because the command line is redrawn, as happens, for example, when a notification about an exiting job is displayed.
preexec
¶Executed just after a command has been read and is about to be executed. If the history mechanism is active (regardless of whether the line was discarded from the history buffer), the string that the user typed is passed as the first argument, otherwise it is an empty string. The actual command that will be executed (including expanded aliases) is passed in two different forms: the second argument is a single-line, size-limited version of the command (with things like function bodies elided); the third argument contains the full text that is being executed.
zshaddhistory
¶Executed when a history line has been read interactively, but before it is executed. The sole argument is the complete history line (so that any terminating newline will still be present).
If any of the hook functions returns status 1 (or any non-zero value other than 2, though this is not guaranteed for future versions of the shell) the history line will not be saved, although it lingers in the history until the next line is executed, allowing you to reuse or edit it immediately.
If any of the hook functions returns status 2 the history line will be saved on the internal history list, but not written to the history file. In case of a conflict, the first non-zero status value is taken.
A hook function may call ‘fc -p
...’ to switch the history
context so that the history is saved in a different file from
that in the global HISTFILE
parameter. This is handled specially:
the history context is automatically restored after the processing
of the history line is finished.
The following example function works with one of the options
INC_APPEND_HISTORY
or SHARE_HISTORY
set, in order that the line
is written out immediately after the history entry is added. It first
adds the history line to the normal history with the newline stripped,
which is usually the correct behaviour. Then it switches the history
context so that the line will be written to a history file in the
current directory.
zshaddhistory() { print -sr -- ${1%%$'\n'} fc -p .zsh_local_history }
zshexit
¶Executed at the point where the main shell is about to exit normally.
This is not called by exiting subshells, nor when the exec
precommand modifier is used before an external command. Also, unlike
TRAPEXIT
, it is not called when functions exit.
The functions below are treated specially but do not have corresponding hook arrays.
TRAP
NAL ¶If defined and non-null,
this function will be executed whenever the shell
catches a signal SIG
NAL, where NAL is a signal
name as specified for the kill
builtin.
The signal number will be passed as the first parameter to the function.
If a function of this form is defined and null,
the shell and processes spawned by it will ignore SIG
NAL.
The return status from the function is handled specially. If it is zero, the signal is assumed to have been handled, and execution continues normally. Otherwise, the shell will behave as interrupted except that the return status of the trap is retained.
Programs terminated by uncaught signals typically return the status 128
plus the signal number. Hence the following causes the handler for
SIGINT
to print a message, then mimic the usual effect of the signal.
TRAPINT() { print "Caught SIGINT, aborting." return $(( 128 + $1 )) }
The functions TRAPZERR
, TRAPDEBUG
and TRAPEXIT
are never
executed inside other traps.
TRAPDEBUG
¶If the option DEBUG_BEFORE_CMD
is set (as it is by default), executed
before each command; otherwise executed after each command. See
the description of the trap
builtin in
Shell Builtin Commands for details of additional features provided
in debug traps.
TRAPEXIT
¶Executed when the shell exits,
or when the current function exits if defined inside a function.
The value of $?
at the start of execution is the exit status of the
shell or the return status of the function exiting.
TRAPZERR
¶Executed whenever a command has a non-zero exit status. However, the
function is not executed if the command occurred in a sublist followed by
‘&&
’ or ‘||
’; only the final command in a sublist of this type
causes the trap to be executed. The function TRAPERR
acts the same as
TRAPZERR
on systems where there is no SIGERR
(this is the usual
case).
The functions beginning ‘TRAP
’ may alternatively be defined with the
trap
builtin: this may be preferable for some uses. Setting a trap
with one form removes any trap of the other form for the same signal;
removing a trap in either form removes all traps for the same signal.
The forms
TRAPNAL() { # code }
(’function traps’) and
trap ' # code ' NAL
(’list traps’) are equivalent in most ways, the exceptions being the following:
If the MONITOR
option is set,
an interactive shell associates a job with each pipeline.
It keeps a table of current jobs, printed by the jobs
command, and assigns them small integer numbers.
When a job is started asynchronously with ‘&
’,
the shell prints a line to standard error which looks like:
[1] 1234
indicating that the job which was started asynchronously was job number 1 and had one (top-level) process, whose process ID was 1234.
If a job is started with ‘&|
’ or ‘&!
’,
then that job is immediately disowned. After startup, it
does not have a place in the job table, and is not subject
to the job control features described here.
If you are running a job and wish to do something else you may hit the key
^Z (control-Z) which sends a TSTP
signal to the current job: this key
may be redefined by the susp
option of the external stty
command.
The shell will then normally indicate that the job has been ‘suspended’,
and print another prompt. You can then manipulate the state of this job,
putting it in the background with the bg
command, or run some other
commands and then eventually bring the job back into the foreground with
the foreground command fg
. A ^Z takes effect immediately and
is like an interrupt in that pending output and unread input are discarded
when it is typed.
A job being run in the background will suspend if it tries to read from the terminal.
Note that if the job running in the foreground is a shell function,
then suspending it will have the effect of causing the shell to fork.
This is necessary to separate the function’s state from that of the
parent shell performing the job control, so that the latter can return
to the command line prompt. As a result, even if fg
is
used to continue the job the function will no longer be part of the
parent shell, and any variables set by the function will not be visible
in the parent shell. Thus the behaviour is different from the case
where the function was never suspended. Zsh is different from many
other shells in this regard.
One additional side effect is that use of disown
with a job
created by suspending shell code in this fashion is delayed: the
job can only be disowned once any process started from the parent
shell has terminated. At that point, the disowned job disappears
silently from the job list.
The same behaviour is found when the shell is executing code as the
right hand side of a pipeline or any complex shell construct such as
if
, for
, etc., in order that the entire block of code
can be managed as a single job.
Background jobs are normally allowed to produce output,
but this can be disabled by giving the command ‘stty tostop
’.
If you set this
tty option, then background jobs will suspend when they try to produce
output like they do when they try to read input.
When a command is suspended and continued later with the fg
or
wait
builtins, zsh restores tty modes that were in effect when it was
suspended. This (intentionally) does not apply if the command is
continued via ‘kill -CONT
’, nor when it is continued with bg
.
There are several ways to refer to jobs in the shell. A job can be referred to by the process ID of any process of the job or by one of the following:
%
numberThe job with the given number.
%
stringThe last job whose command line begins with string.
%?
stringThe last job whose command line contains string.
%%
Current job.
%+
Equivalent to ‘%%
’.
%-
Previous job.
The shell learns immediately whenever a process changes state.
It normally informs you whenever a job becomes blocked so that
no further progress is possible. If the NOTIFY
option is not set,
it waits until just before it prints a prompt before it informs you.
All such notifications are sent directly to the terminal, not to
the standard output or standard error.
When the monitor mode is on, each background job that completes
triggers any trap set for CHLD
.
When you try to leave the shell while jobs are running or suspended, you will
be warned that ‘You have suspended (running) jobs’.
You may use the jobs
command to see what they are.
If you do this or immediately try to
exit again, the shell will not warn you a second time; the suspended
jobs will be terminated, and the running jobs will be sent
a SIGHUP
signal, if the HUP
option is set.
To avoid having the shell terminate the running jobs, either
use the nohup(1) command
or the disown
builtin.
The INT
and QUIT
signals for an invoked
command are ignored if the command is followed by
‘&
’ and the MONITOR
option is not active.
The shell itself always ignores the QUIT
signal.
Otherwise, signals have the values
inherited by the shell from its parent
(but see the TRAP
NAL special functions in Functions).
Certain jobs are run asynchronously by the shell other than those
explicitly put into the background; even in cases where the shell
would usually wait for such jobs, an explicit exit
command
or exit due to the option ERR_EXIT
will cause the shell to
exit without waiting. Examples of such asynchronous jobs are
process substitution, see
Process Substitution, and the handler processes for
multios, see
the section Multios in Redirection.
The shell can perform integer and floating point arithmetic, either using
the builtin let
, or via a substitution of the form
$((
...))
. For
integers, the shell is usually compiled to use 8-byte precision where this
is available, otherwise precision is 4 bytes. This can be tested, for
example, by giving the command ‘print - $(( 12345678901 ))
’; if the
number appears unchanged, the precision is at least 8 bytes. Floating
point arithmetic always uses the ‘double’ type with whatever corresponding
precision is provided by the compiler and the library.
The let
builtin command takes arithmetic expressions as arguments; each
is evaluated separately. Since many of the arithmetic operators, as well
as spaces, require quoting, an alternative form is provided: for any
command which begins with a ‘((
’, all the characters until a
matching ‘))
’ are treated as a double-quoted expression and
arithmetic expansion performed as for an argument of let
. More
precisely, ‘((
...))
’ is equivalent to
‘let "
..."
’. The return status is 0 if the arithmetic value
of the expression is non-zero, 1 if it is zero, and 2 if an error occurred.
For example, the following statement
(( val = 2 + 1 ))
is equivalent to
let "val = 2 + 1"
both assigning the value 3 to the shell variable val
and returning a
zero status.
Integers can be in bases other than 10.
A leading ‘0x
’ or ‘0X
’ denotes hexadecimal and a leading
‘0b
’ or ‘0B
’ binary.
Integers may also be of the form ‘base#
n’,
where base is a decimal number between two and thirty-six
representing the arithmetic base and n
is a number in that base (for example, ‘16#ff
’ is 255 in hexadecimal).
The base#
may also be omitted, in which case
base 10 is used. For backwards compatibility the form
‘[
base]
n’ is also accepted.
An integer expression or a base given in the form
‘base#
n’ may contain underscores (‘_
’) after the
leading digit for visual guidance; these are ignored in computation.
Examples are 1_000_000
or 0xffff_ffff
which are equivalent to
1000000
and 0xffffffff
respectively.
It is also possible to specify a base to be used for output in the form
‘[#
base]
’, for example ‘[#16]
’. This is used when
outputting arithmetical substitutions or when assigning to scalar
parameters, but an explicitly defined integer or floating point parameter
will not be affected. If an integer variable is implicitly defined by an
arithmetic expression, any base specified in this way will be set as the
variable’s output arithmetic base as if the option ‘-i
base’ to
the typeset
builtin had been used. The expression has no precedence
and if it occurs more than once in a mathematical expression, the last
encountered is used. For clarity it is recommended that it appear at the
beginning of an expression. As an example:
typeset -i 16 y print $(( [#8] x = 32, y = 32 )) print $x $y
outputs first ‘8#40
’, the rightmost value in the given output base, and
then ‘8#40 16#20
’, because y
has been explicitly declared to
have output base 16, while x
(assuming it does not already exist) is
implicitly typed by the arithmetic evaluation, where it acquires the output
base 8.
The base may be replaced or followed by an underscore, which may itself be followed by a positive integer (if it is missing the value 3 is used). This indicates that underscores should be inserted into the output string, grouping the number for visual clarity. The following integer specifies the number of digits to group together. For example:
setopt cbases print $(( [#16_4] 65536 ** 2 ))
outputs ‘0x1_0000_0000
’.
The feature can be used with floating point numbers, in which case the base must be omitted; grouping is away from the decimal point. For example,
zmodload zsh/mathfunc print $(( [#_] sqrt(1e7) ))
outputs ‘3_162.277_660_168_379_5
’ (the number of decimal places
shown may vary).
If the C_BASES
option is set, hexadecimal numbers are output in the standard C
format, for example ‘0xFF
’ instead of the usual ‘16#FF
’. If the
option OCTAL_ZEROES
is also set (it is not by default), octal numbers
will be treated similarly and hence appear as ‘077
’ instead of
‘8#77
’. This option has no effect on the output of bases other than
hexadecimal and octal, and these formats are always understood on input.
When an output base is specified using the ‘[#
base]
’ syntax,
an appropriate base prefix will be output if necessary, so that the value
output is valid syntax for input. If the #
is doubled, for example
‘[##16]
’, then no base prefix is output.
Floating point constants are recognized by the presence of a decimal point
or an exponent. The decimal point may be the first character of the
constant, but the exponent character e
or E
may not, as it will be
taken for a parameter name. All numeric parts (before and after the
decimal point and in the exponent) may contain underscores after the
leading digit for visual guidance; these are ignored in computation.
An arithmetic expression uses nearly the same syntax and associativity of expressions as in C.
In the native mode of operation, the following operators are supported (listed in decreasing order of precedence):
+ - ! ~ ++ --
unary plus/minus, logical NOT, complement, {pre,post}{in,de}crement
<< >>
bitwise shift left, right
&
bitwise AND
^
bitwise XOR
|
bitwise OR
**
exponentiation
* / %
multiplication, division, modulus (remainder)
+ -
addition, subtraction
< > <= >=
comparison
== !=
equality and inequality
&&
logical AND
|| ^^
logical OR, XOR
? :
ternary operator
= += -= *= /= %= &= ^= |= <<= >>= &&= ||= ^^= **=
assignment
,
comma operator
The operators ‘&&
’, ‘||
’, ‘&&=
’, and ‘||=
’ are
short-circuiting, and only one of the latter two expressions in a ternary
operator is evaluated. Note the precedence of the bitwise AND, OR,
and XOR operators.
With the option C_PRECEDENCES
the precedences (but no other
properties) of the operators are altered to be the same as those in
most other languages that support the relevant operators:
+ - ! ~ ++ --
unary plus/minus, logical NOT, complement, {pre,post}{in,de}crement
**
exponentiation
* / %
multiplication, division, modulus (remainder)
+ -
addition, subtraction
<< >>
bitwise shift left, right
< > <= >=
comparison
== !=
equality and inequality
&
bitwise AND
^
bitwise XOR
|
bitwise OR
&&
logical AND
^^
logical XOR
||
logical OR
? :
ternary operator
= += -= *= /= %= &= ^= |= <<= >>= &&= ||= ^^= **=
assignment
,
comma operator
Note the precedence of exponentiation in both cases is below
that of unary operators, hence ‘-3**2
’ evaluates as ‘9
’, not
‘-9
’. Use parentheses where necessary: ‘-(3**2)
’. This is
for compatibility with other shells.
Mathematical functions can be called with the syntax
‘func(
args)
’, where the function decides
if the args is used as a string or a comma-separated list of
arithmetic expressions. The shell currently defines no mathematical
functions by default, but the module zsh/mathfunc
may be loaded with
the zmodload
builtin to provide standard floating point mathematical
functions.
An expression of the form ‘##
x’ where x is any character
sequence such as ‘a
’, ‘^A
’, or ‘\M-\C-x
’ gives the value of
this character and an expression of the form ‘#
name’ gives the
value of the first character of the contents of the parameter name.
Character values are according to the character set used in the current
locale; for multibyte character handling the option MULTIBYTE
must be
set. Note that this form is different from ‘$#
name’, a standard
parameter substitution which gives the length of the parameter name.
‘#\
’ is accepted instead of ‘##
’, but its use is deprecated.
Named parameters and subscripted arrays can be referenced by name within an arithmetic expression without using the parameter expansion syntax. For example,
((val2 = val1 * 2))
assigns twice the value of $val1
to the parameter named val2
.
An internal integer representation of a named parameter
can be specified with the integer
builtin.
Arithmetic evaluation is performed on the value of each
assignment to a named parameter declared integer
in this manner. Assigning a floating point number to an integer results in
rounding towards zero.
Likewise, floating point numbers can be declared with the float
builtin; there are two types, differing only in their output format, as
described for the typeset
builtin. The output format can be bypassed
by using arithmetic substitution instead of the parameter substitution,
i.e. ‘${
float}
’ uses the defined format, but
‘$((
float))
’ uses a generic floating point
format.
Promotion of integer to floating point values is performed where
necessary. In addition, if any operator which requires an integer
(‘&
’, ‘|
’, ‘^
’, ‘<<
’, ‘>>
’ and their equivalents with
assignment) is given a floating point argument, it will be silently rounded
towards zero except for ‘~
’ which rounds down.
Users should beware that, in common with many other programming
languages but not software designed for calculation, the evaluation of
an expression in zsh is taken a term at a time and promotion of integers
to floating point does not occur in terms only containing integers. A
typical result of this is that a division such as 6/8
is truncated,
in this being rounded towards 0. The FORCE_FLOAT
shell option can
be used in scripts or functions where floating point evaluation is
required throughout.
Scalar variables can hold integer or floating point values at different times; there is no memory of the numeric type in this case.
If a variable is first assigned in a numeric context without previously
being declared, it will be implicitly typed as integer
or float
and
retain that type either until the type is explicitly changed or until the
end of the scope. This can have unforeseen consequences. For example, in
the loop
for (( f = 0; f < 1; f += 0.1 )); do # use $f done
if f
has not already been declared, the first assignment will cause it
to be created as an integer, and consequently the operation ‘f += 0.1
’
will always cause the result to be truncated to zero, so that the loop will
fail. A simple fix would be to turn the initialization into ‘f = 0.0
’.
It is therefore best to declare numeric variables with explicit types.
A conditional expression is used with the [[
compound command to test attributes of files and to compare strings.
Each expression can be constructed from one or more
of the following unary or binary expressions:
-a
filetrue if file exists.
-b
filetrue if file exists and is a block special file.
-c
filetrue if file exists and is a character special file.
-d
filetrue if file exists and is a directory.
-e
filetrue if file exists.
-f
filetrue if file exists and is a regular file.
-g
filetrue if file exists and has its setgid bit set.
-h
filetrue if file exists and is a symbolic link.
-k
filetrue if file exists and has its sticky bit set.
-n
stringtrue if length of string is non-zero.
-o
optiontrue if option named option is on. option may be a single character, in which case it is a single letter option name. (See Specifying Options.)
When no option named option exists, and the POSIX_BUILTINS
option
hasn’t been set, return 3 with a warning. If that option is set, return 1
with no warning.
-p
filetrue if file exists and is a FIFO special file (named pipe).
-r
filetrue if file exists and is readable by current process.
-s
filetrue if file exists and has size greater than zero.
-t
fdtrue if file descriptor number fd is open and associated with a terminal device. (note: fd is not optional)
-u
filetrue if file exists and has its setuid bit set.
-v
varnametrue if shell variable varname is set.
-w
filetrue if file exists and is writable by current process.
-x
filetrue if file exists and is executable by current process. If file exists and is a directory, then the current process has permission to search in the directory.
-z
stringtrue if length of string is zero.
-L
filetrue if file exists and is a symbolic link.
-O
filetrue if file exists and is owned by the effective user ID of this process.
-G
filetrue if file exists and its group matches the effective group ID of this process.
-S
filetrue if file exists and is a socket.
-N
filetrue if file exists and its access time is not newer than its modification time.
-nt
file2true if file1 exists and is newer than file2.
-ot
file2true if file1 exists and is older than file2.
-ef
file2true if file1 and file2 exist and refer to the same file.
=
pattern==
patterntrue if string matches pattern.
The two forms are exactly equivalent. The ‘=
’ form is
the traditional shell syntax (and hence the only one generally used
with the test
and [
builtins); the ‘==
’ form provides
compatibility with other sorts of computer language.
!=
patterntrue if string does not match pattern.
=~
regexptrue if string matches the regular expression
regexp. If the option RE_MATCH_PCRE
is set
regexp is tested as a PCRE regular expression using
the zsh/pcre
module, else it is tested as a POSIX
extended regular expression using the zsh/regex
module.
Upon successful match, some variables will be updated; no variables
are changed if the matching fails.
If the option BASH_REMATCH
is not set the scalar parameter
MATCH
is set to the substring that matched the pattern and
the integer parameters MBEGIN
and MEND
to the index of the start
and end, respectively, of the match in string, such that if
string is contained in variable var
the expression
‘${var[$MBEGIN,$MEND]}
’ is identical to ‘$MATCH
’. The setting
of the option KSH_ARRAYS
is respected. Likewise, the array
match
is set to the substrings that matched parenthesised
subexpressions and the arrays mbegin
and mend
to the indices of
the start and end positions, respectively, of the substrings within
string. The arrays are not set if there were no parenthesised
subexpressions. For example, if the string ‘a short string
’ is matched
against the regular expression ‘s(...)t
’, then (assuming the
option KSH_ARRAYS
is not set) MATCH
, MBEGIN
and MEND
are ‘short
’, 3
and 7
, respectively, while match
,
mbegin
and mend
are single entry arrays containing
the strings ‘hor
’, ‘4
’ and ‘6
’, respectively.
If the option BASH_REMATCH
is set the array
BASH_REMATCH
is set to the substring that matched the pattern
followed by the substrings that matched parenthesised
subexpressions within the pattern.
<
string2true if string1 comes before string2 based on ASCII value of their characters.
>
string2true if string1 comes after string2 based on ASCII value of their characters.
-eq
exp2true if exp1 is numerically equal to exp2.
Note that for purely numeric comparisons use of the
((
...))
builtin described in
Arithmetic Evaluation is more convenient than
conditional expressions.
-ne
exp2true if exp1 is numerically not equal to exp2.
-lt
exp2true if exp1 is numerically less than exp2.
-gt
exp2true if exp1 is numerically greater than exp2.
-le
exp2true if exp1 is numerically less than or equal to exp2.
-ge
exp2true if exp1 is numerically greater than or equal to exp2.
(
exp )
true if exp is true.
!
exptrue if exp is false.
&&
exp2true if exp1 and exp2 are both true.
||
exp2true if either exp1 or exp2 is true.
For compatibility, if there is a single argument that is not
syntactically significant, typically a variable, the condition is
treated as a test for whether the expression expands as a string of
non-zero length. In other words, [[ $var ]]
is the same as [[ -n
$var ]]
. It is recommended that the second, explicit, form be used
where possible.
Normal shell expansion is performed on the file, string and pattern arguments, but the result of each expansion is constrained to be a single word, similar to the effect of double quotes.
Filename generation is not performed on any form of argument to
conditions. However, it can be forced in any case where normal shell
expansion is valid and when the option EXTENDED_GLOB
is in effect by
using an explicit glob qualifier of the form (#q)
at the
end of the string. A normal glob qualifier expression may appear
between the ‘q
’ and the closing parenthesis; if none appears the
expression has no effect beyond causing filename generation. The
results of filename generation are joined together to form a single
word, as with the results of other forms of expansion.
This special use of filename generation is only available with the
[[
syntax. If the condition occurs within the [
or test
builtin commands then globbing occurs instead as part of normal command
line expansion before the condition is evaluated. In this case it may
generate multiple words which are likely to confuse the syntax of the
test command.
For example,
[[ -n file*(#qN) ]]
produces status zero if and only if there is at least one file in the
current directory beginning with the string ‘file
’. The globbing
qualifier N
ensures that the expression is empty if there is
no matching file.
Pattern metacharacters are active for the pattern arguments;
the patterns are the same as those used for filename generation, see
Filename Generation, but there is no special behaviour
of ‘/
’ nor initial dots, and no glob qualifiers are allowed.
In each of the above expressions, if
file is of the form ‘/dev/fd/
n’,
where n is an integer,
then the test applied to the open file whose
descriptor number is n,
even if the underlying system does not support
the /dev/fd
directory.
In the forms which do numeric comparison, the expressions exp
undergo arithmetic expansion as if they were enclosed in
$((
...))
.
For example, the following:
[[ ( -f foo || -f bar ) && $report = y* ]] && print File exists.
tests if either file foo
or file bar
exists, and if so, if the
value of the parameter report
begins with ‘y
’; if the complete
condition is true, the message ‘File exists.
’ is printed.
Prompt sequences undergo a special form of expansion. This type of expansion
is also available using the -P
option to the print
builtin.
If the PROMPT_SUBST
option is set, the prompt string is first subjected to
parameter expansion,
command substitution and
arithmetic expansion.
See
Expansion.
Certain escape sequences may be recognised in the prompt string.
If the PROMPT_BANG
option is set, a ‘!
’ in the prompt is replaced
by the current history event number. A literal ‘!
’ may then be
represented as ‘!!
’.
If the PROMPT_PERCENT
option is set, certain escape sequences that
start with ‘%
’ are expanded.
Many escapes are followed by a single character, although some of these
take an optional integer argument that
should appear between the ‘%
’ and the next character of the
sequence. More complicated escape sequences are available to provide
conditional expansion.
%%
A ‘%
’.
%)
A ‘)
’.
%l
The line (tty) the user is logged in on, without ‘/dev/
’ prefix.
If the name starts with ‘/dev/tty
’, that prefix is stripped.
%M
The full machine hostname.
%m
The hostname up to the first ‘.
’.
An integer may follow the ‘%
’ to specify
how many components of the hostname are desired. With a negative integer,
trailing components of the hostname are shown.
%n
$USERNAME
.
%y
The line (tty) the user is logged in on, without ‘/dev/
’ prefix.
This does not treat ‘/dev/tty
’ names specially.
%#
A ‘#
’ if the shell is running with privileges, a ‘%
’ if not.
Equivalent to ‘%(!.#.%%)
’.
The definition of ‘privileged’, for these purposes, is that either the
effective user ID is zero, or, if POSIX.1e capabilities are supported, that
at least one capability is raised in either the Effective or Inheritable
capability vectors.
%?
The return status of the last command executed just before the prompt.
%_
The status of the parser, i.e. the shell constructs (like ‘if
’ and
‘for
’) that have been started on the command line. If given an integer
number that many strings will be printed; zero or negative or no integer means
print as many as there are. This is most useful in prompts PS2
for
continuation lines and PS4
for debugging with the XTRACE
option; in
the latter case it will also work non-interactively.
%^
The status of the parser in reverse. This is the same as ‘%_
’ other than
the order of strings. It is often used in RPS2
.
%d
%/
Current working directory. If an integer follows the ‘%
’,
it specifies a number of trailing components of the current working
directory to show; zero means the whole path. A negative integer
specifies leading components, i.e. %-1d
specifies the first component.
%~
As %d
and %/
, but if the current working directory starts with
$HOME
, that part is replaced by a ‘~
’. Furthermore, if it has a named
directory as its prefix, that part is replaced by a ‘~
’ followed by
the name of the directory, but only if the result is shorter than
the full path;
Filename Expansion.
%e
Evaluation depth of the current sourced file, shell function, or eval
.
This is incremented or decremented every time the value of %N
is
set or reverted to a previous value, respectively. This is most useful
for debugging as part of $PS4
.
%h
%!
Current history event number.
%i
The line number currently being executed in the script, sourced file, or
shell function given by %N
. This is most useful for debugging as part
of $PS4
.
%I
The line number currently being executed in the file %x
. This is
similar to %i
, but the line number is always a line number in the
file where the code was defined, even if the code is a shell function.
%j
The number of jobs.
%L
The current value of $SHLVL
.
%N
The name of the script, sourced file, or shell function that zsh is
currently executing, whichever was started most recently. If there is
none, this is equivalent to the parameter $0
. An integer may follow
the ‘%
’ to specify a number of trailing path components to show; zero
means the full path. A negative integer specifies leading components.
%x
The name of the file containing the source code currently being
executed. This behaves as %N
except that function and eval command
names are not shown, instead the file where they were defined.
%c
%.
%C
Trailing component of the current working directory.
An integer may follow the ‘%
’ to get more than one component.
Unless ‘%C
’ is used, tilde contraction is performed first. These are
deprecated as %c
and %C
are equivalent to %1~
and %1/
,
respectively, while explicit positive integers have the same effect as for
the latter two sequences.
%D
The date in yy-
mm-
dd format.
%T
Current time of day, in 24-hour format.
%t
%@
Current time of day, in 12-hour, am/pm format.
%*
Current time of day in 24-hour format, with seconds.
%w
The date in day-
dd format.
%W
The date in mm/
dd/
yy format.
%D{
string}
string is formatted using the strftime
function.
See strftime(3) for more details. Various zsh
extensions provide numbers with no leading zero or space
if the number is a single digit:
%f
a day of the month
%K
the hour of the day on the 24-hour clock
%L
the hour of the day on the 12-hour clock
In addition, if the system supports the POSIX gettimeofday
system
call, %.
provides decimal fractions of a second since the epoch with
leading zeroes. By default three decimal places are provided, but a
number of digits up to 9 may be given following the %
; hence %6.
outputs microseconds, and %9.
outputs nanoseconds. (The latter
requires a nanosecond-precision clock_gettime
; systems lacking this
will return a value multiplied by the appropriate power of 10.) A typical
example of this is the format ‘%D{%H:%M:%S.%.}
’.
The GNU extension %N
is handled as a synonym for %9.
.
Additionally, the GNU extension that a ‘-
’ between the %
and the
format character causes a leading zero or space to be stripped
is handled directly by the shell for the format characters d
, f
,
H
, k
, l
, m
, M
, S
and y
; any other format
characters are provided to the system’s strftime(3)
with any leading ‘-
’ present, so the handling is system dependent.
Further GNU (or other) extensions are also passed to strftime(3)
and may work if the system supports them.
%B
(%b
)Start (stop) boldface mode.
%E
Clear to end of line.
%U
(%u
)Start (stop) underline mode.
%S
(%s
)Start (stop) standout mode.
%F
(%f
)Start (stop) using a different foreground colour, if supported
by the terminal. The colour may be specified two ways: either
as a numeric argument, as normal, or by a sequence in braces
following the %F
, for example %F{red}
. In the latter case
the values allowed are as described for the fg
zle_highlight
attribute;
Character Highlighting. This means that numeric
colours are allowed in the second format also.
%K
(%k
)Start (stop) using a different bacKground colour. The syntax is
identical to that for %F
and %f
.
%{
...%}
Include a string as a literal escape sequence. The string within the braces should not change the cursor position. Brace pairs can nest.
A positive numeric argument between the %
and the {
is treated as
described for %G
below.
%G
Within a %{
...%}
sequence, include a ‘glitch’: that is, assume
that a single character width will be output. This is useful when
outputting characters that otherwise cannot be correctly handled by the
shell, such as the alternate character set on some terminals.
The characters in question can be included within a %{
...%}
sequence together with the appropriate number of %G
sequences to
indicate the correct width. An integer between the ‘%
’ and ‘G
’
indicates a character width other than one. Hence %{
seq%2G%}
outputs seq and assumes it takes up the width of two standard
characters.
Multiple uses of %G
accumulate in the obvious fashion; the position
of the %G
is unimportant. Negative integers are not handled.
Note that when prompt truncation is in use it is advisable to divide up
output into single characters within each %{
...%}
group so that
the correct truncation point can be found.
%v
¶The value of the first element of the psvar
array parameter. Following
the ‘%
’ with an integer gives that element of the array. Negative
integers count from the end of the array.
%(
x.
true-text.
false-text)
Specifies a ternary expression. The character following the x is
arbitrary; the same character is used to separate the text for the
‘true’ result from that for the ‘false’ result.
This separator may not appear in the true-text, except as part of a
%-escape
sequence. A ‘)
’ may appear in the false-text as ‘%)
’.
true-text
and false-text may both contain arbitrarily-nested escape
sequences, including further ternary expressions.
The left parenthesis may be preceded or followed by a positive integer n,
which defaults to zero. A negative integer will be multiplied by -1, except
as noted below for ‘l
’.
The test character x may be any of the following:
!
True if the shell is running with privileges.
#
True if the effective uid of the current process is n.
?
True if the exit status of the last command was n.
_
True if at least n shell constructs were started.
C
/
True if the current absolute path has at least n elements
relative to the root directory, hence /
is counted as 0 elements.
c
.
~
True if the current path, with prefix replacement, has at
least n elements relative to the root directory, hence /
is
counted as 0 elements.
D
True if the month is equal to n (January = 0).
d
True if the day of the month is equal to n.
e
True if the evaluation depth is at least n.
g
True if the effective gid of the current process is n.
j
True if the number of jobs is at least n.
L
True if the SHLVL
parameter is at least n.
l
True if at least n characters have already been
printed on the current line. When n is negative, true if at least
abs
(
n)
characters remain before the opposite
margin (thus the left margin for RPROMPT
).
S
True if the SECONDS
parameter is at least n.
T
True if the time in hours is equal to n.
t
True if the time in minutes is equal to n.
v
True if the array psvar
has at least n elements.
V
True if element n of the array psvar
is set and
non-empty.
w
True if the day of the week is equal to n (Sunday = 0).
%<
string<
%>
string>
%[
xstring]
Specifies truncation behaviour for the remainder of the prompt string.
The third, deprecated, form is equivalent to ‘%
xstringx’,
i.e. x may be ‘<
’ or ‘>
’.
The string will be displayed in
place of the truncated portion of any string; note this does not
undergo prompt expansion.
The numeric argument, which in the third form may appear immediately
after the ‘[
’, specifies the maximum permitted length of
the various strings that can be displayed in the prompt.
In the first two forms, this numeric argument may be negative, in which
case the truncation length is determined by subtracting the absolute
value of the numeric argument from the number of character positions
remaining on the current prompt line. If this results in a zero or
negative length, a length of 1 is used. In other words, a negative
argument arranges that after truncation at least n characters
remain before the right margin (left margin for RPROMPT
).
The forms with ‘<
’ truncate at the left of the string,
and the forms with ‘>
’ truncate at the right of the string.
For example, if the current directory is ‘/home/pike
’,
the prompt ‘%8<..<%/
’ will expand to ‘..e/pike
’.
In this string, the terminating character (‘<
’, ‘>
’ or ‘]
’),
or in fact any character, may be quoted by a preceding ‘\
’; note
when using print -P
, however, that this must be doubled as the
string is also subject to standard print
processing, in addition
to any backslashes removed by a double quoted string: the worst case
is therefore ‘print -P "%<\\\\<<..."
’.
If the string is longer than the specified truncation length, it will appear in full, completely replacing the truncated string.
The part of the prompt string to be truncated runs to the end of the
string, or to the end of the next enclosing group of the ‘%(
’
construct, or to the next truncation encountered at the same grouping
level (i.e. truncations inside a ‘%(
’ are separate), which
ever comes first. In particular, a truncation with argument zero
(e.g., ‘%<<
’) marks the end of the range of the string to be
truncated while turning off truncation from there on. For example, the
prompt ‘%10<...<%~%<<%#
’ will print a truncated representation of the
current directory, followed by a ‘%
’ or ‘#
’, followed by a
space. Without the ‘%<<
’, those two characters would be included
in the string to be truncated. Note that ‘%-0<<
’ is not equivalent
to ‘%<<
’ but specifies that the prompt is truncated at the right margin.
Truncation applies only within each individual line of the prompt, as
delimited by embedded newlines (if any). If the total length of any line
of the prompt after truncation is greater than the terminal width, or if
the part to be truncated contains embedded newlines, truncation behavior
is undefined and may change in a future version of the shell. Use
‘%-
n(l.
true-text.
false-text)
’ to remove parts
of the prompt when the available space is less than n.
The following types of expansions are performed in the indicated order in five steps:
This is performed only in interactive shells.
Aliases are expanded immediately before the command line is parsed as explained in Aliasing.
These five are performed in left-to-right fashion. On each argument,
any of the five steps that are needed are performed one after the other.
Hence, for example, all the parts of parameter expansion are completed
before command substitution is started. After these expansions, all
unquoted occurrences of the characters ‘\
’,‘'
’ and ‘"
’ are
removed.
If the SH_FILE_EXPANSION
option is set, the order of expansion is
modified for compatibility with sh and ksh. In that case
filename expansion is performed immediately after alias expansion,
preceding the set of five expansions mentioned above.
This expansion, commonly referred to as globbing, is always done last.
The following sections explain the types of expansion in detail.
History expansion allows you to use words from previous command lines in the command line you are typing. This simplifies spelling corrections and the repetition of complicated commands or arguments.
Immediately before execution, each command is saved in the history list,
the size of which is controlled by the HISTSIZE
parameter. The one
most recent command is always retained in any case. Each saved command in
the history list is called a history event and is assigned a number,
beginning with 1 (one) when the shell starts up. The history number that
you may see in your prompt (see
Prompt Expansion) is the number that is to be assigned to the next command.
A history expansion begins with the first character of the histchars
parameter, which is ‘!
’ by default, and may occur anywhere on the
command line, including inside double quotes (but not inside single quotes
'...'
or C-style quotes $'...'
nor when escaped with a backslash).
The first character is followed by an optional event designator (Event Designators) and then an optional word designator (Word Designators); if neither of these designators is present, no history expansion occurs.
Input lines containing history expansions are echoed after being expanded, but before any other expansions take place and before the command is executed. It is this expanded form that is recorded as the history event for later references.
History expansions do not nest.
By default, a history reference with no event designator refers to the
same event as any preceding history reference on that command line; if it
is the only history reference in a command, it refers to the previous
command.
However, if the option CSH_JUNKIE_HISTORY
is set, then every history
reference with no event specification always refers to the previous
command.
For example, ‘!
’ is the event designator for the previous command, so
‘!!:1
’ always refers to the first word of the previous command, and
‘!!$
’ always refers to the last word of the previous command. With
CSH_JUNKIE_HISTORY
set, then ‘!:1
’ and ‘!$
’ function in the
same manner as ‘!!:1
’ and ‘!!$
’, respectively. Conversely, if
CSH_JUNKIE_HISTORY
is unset, then ‘!:1
’ and ‘!$
’ refer to the
first and last words, respectively, of the same event referenced by the
nearest other history reference preceding them on the current command
line, or to the previous command if there is no preceding reference.
The character sequence ‘^
foo^
bar’ (where ‘^
’ is
actually the second character of the histchars
parameter)
repeats the last command, replacing the string foo with bar.
More precisely, the sequence ‘^
foo^
bar^
’ is
synonymous with ‘!!:s
^
foo^
bar^
’, hence other
modifiers (see Modifiers) may follow the final ‘^
’.
In particular, ‘^
foo^
bar^:G
’ performs a global
substitution.
If the shell encounters the character sequence ‘!"
’
in the input, the history mechanism is temporarily disabled until
the current list (see
Shell Grammar) is fully parsed. The ‘!"
’ is removed from the input, and any
subsequent ‘!
’ characters have no special significance.
A less convenient but more comprehensible form of command history support
is provided by the fc
builtin.
An event designator is a reference to a command-line entry in the history
list. In the list below, remember that the initial `!'
in each item
may be changed to another character by setting the histchars
parameter.
!
Start a history expansion, except when followed by a blank, newline,
‘=
’ or ‘(
’. If followed immediately by a word designator
(Word Designators), this forms a history reference
with no event designator (Overview).
!!
Refer to the previous command. By itself, this expansion repeats the previous command.
!
nRefer to command-line n.
!-
nRefer to the current command-line minus n.
!
strRefer to the most recent command starting with str.
!?
str[?
]Refer to the most recent command containing str. The trailing
‘?
’ is necessary if this reference is to be followed by a modifier or
followed by any text that is not to be considered part of str.
!#
Refer to the current command line typed in so far. The line is
treated as if it were complete up to and including the word before the
one with the ‘!#
’ reference.
!{
...}
Insulate a history reference from adjacent characters (if necessary).
A word designator indicates which word or words of a given command line are
to be included in a history reference. A ‘:
’ usually
separates the event specification from the word designator.
It may be omitted only if the word designator begins with a
‘^
’, ‘$
’, ‘*
’, ‘-
’ or ‘%
’.
Word designators include:
0
The first input word (command).
The nth argument.
^
The first argument. That is, 1
.
$
The last argument.
%
The word matched by (the most recent) ?
str search.
-
yA range of words; x defaults to 0
.
*
All the arguments, or a null value if there are none.
*
Abbreviates ‘x-$
’.
-
Like ‘x*
’ but omitting word $
.
Note that a ‘%
’ word designator works only when used in one of
‘!%
’, ‘!:%
’ or ‘!?
str?:%
’, and only when used after a
!?
expansion (possibly in an earlier command). Anything else results
in an error, although the error may not be the most obvious one.
After the optional word designator, you can add
a sequence of one or more of the following modifiers,
each preceded by a ‘:
’. These modifiers also work on the result
of filename generation and parameter expansion, except where
noted.
a
Turn a file name into an absolute path: prepends the current directory,
if necessary; remove ‘.
’ path segments; and remove ‘..
’ path segments
and the segments that immediately precede them.
This transformation is agnostic about what is in the filesystem, i.e. is
on the logical, not the physical directory. It takes place in the same
manner as when changing directories when neither of the options
CHASE_DOTS
or CHASE_LINKS
is set. For example,
‘/before/here/../after
’ is always transformed to
‘/before/after
’, regardless of whether ‘/before/here
’ exists or what
kind of object (dir, file, symlink, etc.) it is.
A
Turn a file name into an absolute path as the ‘a
’ modifier does, and
then pass the result through the realpath(3)
library
function to resolve symbolic links.
Note: on systems that do not have a realpath(3)
library
function, symbolic links are not resolved, so on those systems ‘a
’ and
‘A
’ are equivalent.
Note: foo:A
and realpath(foo)
are different on some inputs.
For realpath(foo)
semantics, see the ‘P
‘ modifier.
c
Resolve a command name into an absolute path by searching the command
path given by the PATH
variable. This does not work for commands
containing directory parts. Note also that this does not usually work as
a glob qualifier unless a file of the same name is found in the
current directory.
e
Remove all but the part of the filename extension following the ‘.
’;
see the definition of the filename extension in the description of the
r
modifier below. Note that according to that definition the result
will be empty if the string ends with a ‘.
’.
h
[ digits ]Remove a trailing pathname component, shortening the path by one
directory level: this is the ‘head’ of the pathname. This works like
‘dirname
’. If the h
is followed immediately (with no spaces or
other separator) by any number of decimal digits, and the value of the
resulting number is non-zero, that number of leading components is
preserved instead of the final component being removed. In an
absolute path the leading ‘/
’ is the first component, so,
for example, if var=/my/path/to/something
, then ${var:h3}
substitutes /my/path
. Consecutive ‘/’s are treated the same as
a single ‘/’. In parameter substitution, digits may only be
used if the expression is in braces, so for example the short form
substitution $var:h2
is treated as ${var:h}2
, not as
${var:h2}
. No restriction applies to the use of digits in history
substitution or globbing qualifiers. If more components are requested
than are present, the entire path is substituted (so this does not
trigger a ‘failed modifier’ error in history expansion).
l
Convert the words to all lowercase.
p
Print the new command but do not execute it. Only works with history expansion.
P
Turn a file name into an absolute path, like realpath(3)
.
The resulting path will be absolute,
will refer to the same directory entry as the input filename,
and none of its components will be symbolic links or equal to
‘.
’ or ‘..
’.
Unlike realpath(3)
, non-existent trailing components are
permitted and preserved.
q
Quote the substituted words, escaping further substitutions. Works
with history expansion and parameter expansion, though for parameters
it is only useful if the resulting text is to be re-evaluated such as
by eval
.
Q
Remove one level of quotes from the substituted words.
r
Remove a filename extension leaving the root name. Strings with no
filename extension are not altered. A filename
extension is a ‘.
’ followed by any number of characters (including
zero) that are neither ‘.
’ nor ‘/
’ and that continue to the end
of the string. For example, the extension of
‘foo.orig.c
’ is ‘.c
’, and ‘dir.c/foo
’ has no extension.
s/
l/
r[/
]Substitute r for l as described below. The substitution is done only for the first string that matches l. For arrays and for filename generation, this applies to each word of the expanded text. See below for further notes on substitutions.
The forms ‘gs/
l/
r’ and ‘s/
l/
r/:G
’
perform global substitution, i.e. substitute every occurrence of r
for l. Note that the g
or :G
must appear in exactly the
position shown.
See further notes on this form of substitution below.
&
Repeat the previous s
substitution. Like s
, may be preceded
immediately by a g
. In parameter expansion the &
must appear
inside braces, and in filename generation it must be quoted with a
backslash.
t
[ digits ]Remove all leading pathname components, leaving the final component (tail).
This works like ‘basename
’. Any trailing slashes are first removed.
Decimal digits are handled as described above for (h), but in this
case that number of trailing components is preserved instead of
the default 1; 0 is treated the same as 1.
u
Convert the words to all uppercase.
x
Like q
, but break into words at whitespace. Does not work with
parameter expansion.
The s/
l/
r/
substitution works as follows. By
default the left-hand side of substitutions are not patterns, but
character strings. Any character can be used as the delimiter in place
of ‘/
’. A backslash quotes the delimiter character. The character
‘&
’, in the right-hand-side r, is replaced by the text from the
left-hand-side l. The ‘&
’ can be quoted with a backslash. A
null l uses the previous string either from the previous l or
from the contextual scan string s from ‘!?
s’. You can
omit the rightmost delimiter if a newline immediately follows r;
the rightmost ‘?
’ in a context scan can similarly be omitted. Note
the same record of the last l and r is maintained across all
forms of expansion.
Note that if a ‘&
’ is used within glob qualifiers an extra backslash
is needed as a &
is a special character in this case.
Also note that the order of expansions affects the interpretation of
l and r. When used in a history expansion, which occurs before
any other expansions, l and r are treated as literal strings
(except as explained for HIST_SUBST_PATTERN
below). When used in
parameter expansion, the replacement of r into the parameter’s value
is done first, and then any additional process, parameter, command,
arithmetic, or brace references are applied, which may evaluate those
substitutions and expansions more than once if l appears more than
once in the starting value. When used in a glob qualifier, any
substitutions or expansions are performed once at the time the qualifier
is parsed, even before the ‘:s
’ expression itself is divided into
l and r sides.
If the option HIST_SUBST_PATTERN
is set, l is treated as
a pattern of the usual form described in
Filename Generation. This can be used in
all the places where modifiers are available; note, however, that
in globbing qualifiers parameter substitution has already taken place,
so parameters in the replacement string should be quoted to ensure
they are replaced at the correct time.
Note also that complicated patterns used in globbing qualifiers may
need the extended glob qualifier notation
(#q:s/
.../
.../)
in order for the
shell to recognize the expression as a glob qualifier. Further,
note that bad patterns in the substitution are not subject to
the NO_BAD_PATTERN
option so will cause an error.
When HIST_SUBST_PATTERN
is set, l may start with a #
to indicate that the pattern must match at the start of the string
to be substituted, and a %
may appear at the start or after an #
to indicate that the pattern must match at the end of the string
to be substituted. The %
or #
may be quoted with two
backslashes.
For example, the following piece of filename generation code
with the EXTENDED_GLOB
option:
print -r -- *.c(#q:s/#%(#b)s(*).c/'S${match[1]}.C'/)
takes the expansion of *.c
and applies the glob qualifiers in the
(#q
...)
expression, which consists of a substitution
modifier anchored to the start and end of each word (#%
). This
turns on backreferences ((#b)
), so that the parenthesised
subexpression is available in the replacement string as ${match[1]}
.
The replacement string is quoted so that the parameter is not substituted
before the start of filename generation.
The following f
, F
, w
and W
modifiers work only with
parameter expansion and filename generation. They are listed here to
provide a single point of reference for all modifiers.
f
Repeats the immediately (without a colon) following modifier until the resulting word doesn’t change any more.
F:
expr:
Like f
, but repeats only n times if the expression
expr evaluates to n. Any character can be used instead of
the ‘:
’; if ‘(
’, ‘[
’, or ‘{
’
is used as the opening delimiter,
the closing delimiter should be ’)
’, ‘]
’, or ‘}
’,
respectively.
w
Makes the immediately following modifier work on each word in the string.
W:
sep:
Like w
but words are considered to be the parts of the string
that are separated by sep. Any character can be used instead of
the ‘:
’; opening parentheses are handled specially, see above.
Each part of a command argument that takes the form
‘<(
list)
’,
‘>(
list)
’ or
‘=(
list)
’
is subject to process substitution. The expression may be preceded
or followed by other strings except that, to prevent clashes with
commonly occurring strings and patterns, the last
form must occur at the start of a command argument, and the forms
are only expanded when first parsing command or assignment arguments.
Process substitutions may be used following redirection operators; in this
case, the substitution must appear with no trailing string.
Note that ‘<<(
list)
’ is not a special syntax; it
is equivalent to ‘< <(
list)
’, redirecting
standard input from the result of process substitution. Hence all
the following documentation applies. The second form (with the space)
is recommended for clarity.
In the case of the <
or >
forms, the shell runs the commands in
list as a subprocess of the job executing the shell command line.
If the system supports the /dev/fd
mechanism, the command argument is the name of the device file
corresponding to a file descriptor; otherwise, if the system supports named
pipes (FIFOs), the command argument will be a named pipe. If the form with
>
is selected then writing on this special file will provide input for
list. If <
is used, then the file passed as an argument will
be connected to the output of the list process. For example,
paste <(cut -f1
file1) <(cut -f3
file2) | tee >(
process1) >(
process2) >/dev/null
cuts fields 1 and 3 from the files file1 and file2 respectively, pastes the results together, and sends it to the processes process1 and process2.
If =(
...)
is used instead of
<(
...)
,
then the file passed as an argument will be the name
of a temporary file containing the output of the list
process. This may be used instead of the <
form for a program that expects to lseek (see lseek(2))
on the input file.
There is an optimisation for substitutions of the form
=(<<<
arg)
, where arg is a single-word argument
to the here-string redirection <<<
. This form produces a file name
containing the value of arg after any substitutions have been
performed. This is handled entirely within the current shell. This is
effectively the reverse of the special form $(<
arg)
which treats arg as a file name and replaces it with the file’s
contents.
The =
form is useful as both the /dev/fd
and the named pipe
implementation of <(
...)
have drawbacks. In
the former case, some programmes may automatically close the file
descriptor in question before examining the file on the command line,
particularly if this is necessary for security reasons such as when the
programme is running setuid. In the second case, if the
programme does not actually open the file, the subshell attempting to read
from or write to the pipe will (in a typical implementation, different
operating systems may have different behaviour) block for ever and have to
be killed explicitly. In both cases, the shell actually supplies the
information using a pipe, so that programmes that expect to lseek
(see lseek(2)) on the file will not work.
Also note that the previous example can be more compactly and
efficiently written (provided the MULTIOS
option is set) as:
paste <(cut -f1
file1) <(cut -f3
file2)
> >(
process1) > >(
process2)
The shell uses pipes instead of FIFOs to implement the latter two process substitutions in the above example.
There is an additional problem with >(
process)
; when
this is attached to an external command, the parent shell does not wait
for process to finish and hence an immediately following command
cannot rely on the results being complete. The problem and solution are
the same as described in the section MULTIOS in
Redirection. Hence in a simplified
version of the example above:
paste <(cut -f1
file1) <(cut -f3
file2)
> >(
process)
(note that no MULTIOS
are involved), process will be run
asynchronously as far as the parent shell is concerned. The workaround is:
{ paste <(cut -f1
file1) <(cut -f3
file2) }
> >(
process)
The extra processes here are spawned from the parent shell which will wait for their completion.
Another problem arises any time a job with a substitution that requires
a temporary file is disowned by the shell, including the case where
‘&!
’ or ‘&|
’ appears at the end of a command containing a
substitution. In that case the temporary file will not be cleaned up as
the shell no longer has any memory of the job. A workaround is to use
a subshell, for example,
(mycmd =(myoutput)) &!
as the forked subshell will wait for the command to finish then remove the temporary file.
A general workaround to ensure a process substitution endures for an appropriate length of time is to pass it as a parameter to an anonymous shell function (a piece of shell code that is run immediately with function scope). For example, this code:
() { print File $1: cat $1 } =(print This be the verse)
outputs something resembling the following
File /tmp/zsh6nU0kS: This be the verse
The temporary file created by the process substitution will be deleted when the function exits.
The character ‘$
’ is used to introduce parameter expansions.
See
Parameters
for a description of parameters, including arrays, associative arrays,
and subscript notation to access individual array elements.
Note in particular the fact that words of unquoted parameters are not
automatically split on whitespace unless the option SH_WORD_SPLIT
is
set; see references to this option below for more details. This is an
important difference from other shells. However, as in other shells,
null words are elided from unquoted parameters’ expansions.
With default options, after the assignments:
array=("first word" "" "third word") scalar="only word"
then $array
substitutes two words, ‘first word
’ and ‘third
word
’, and $scalar
substitutes a single word ‘only word
’. Note
that second element of array
was elided. Scalar parameters can
be elided too if their value is null (empty). To avoid elision, use quoting as
follows: "$scalar"
for scalars and "${array[@]}"
or "${(@)array}"
for arrays. (The last two forms are equivalent.)
Parameter expansions can involve flags, as in ‘${(@kv)aliases}
’,
and other operators, such as ‘${PREFIX:-"/usr/local"}
’. Parameter
expansions can also be nested. These topics will be introduced below.
The full rules are complicated and are noted at the end.
In the expansions discussed below that require a pattern, the form of
the pattern is the same as that used for filename generation;
see Filename Generation. Note that these patterns, along with
the replacement text of any substitutions, are themselves subject to
parameter expansion, command substitution, and arithmetic expansion.
In addition to the following operations, the colon modifiers described in
Modifiers in History Expansion can be
applied: for example, ${i:s/foo/bar/}
performs string
substitution on the expansion of parameter $i
.
In the following descriptions, ‘word’ refers to a single word substituted on the command line, not necessarily a space delimited word.
${
name}
The value, if any, of the parameter name is substituted.
The braces are required if the expansion is to be followed by
a letter, digit, or underscore that is not to be interpreted
as part of name. In addition, more complicated forms of substitution
usually require the braces to be present; exceptions, which only apply if
the option KSH_ARRAYS
is not set, are a single subscript or any colon
modifiers appearing after the name, or any of the characters ‘^
’,
‘=
’, ‘~
’, ‘#
’ or ‘+
’ appearing before the name, all of
which work with or without braces.
If name is an array parameter, and the KSH_ARRAYS
option is not
set, then the value of each
element of name is substituted, one element per word. Otherwise, the
expansion results in one word only; with KSH_ARRAYS
, this is the first
element of an array. No field splitting is done on the result unless the
SH_WORD_SPLIT
option is set.
See also the flags =
and s:
string:
.
${+
name}
If name is the name of a set parameter ‘1
’ is substituted,
otherwise ‘0
’ is substituted.
${
name-
word}
${
name:-
word}
If name is set, or in the second form is non-null, then substitute its value; otherwise substitute word. In the second form name may be omitted, in which case word is always substituted.
${
name+
word}
${
name:+
word}
If name is set, or in the second form is non-null, then substitute word; otherwise substitute nothing.
${
name=
word}
${
name:=
word}
${
name::=
word}
In the first form, if name is unset then set it to word; in the second form, if name is unset or null then set it to word; and in the third form, unconditionally set name to word. In all forms, the value of the parameter is then substituted.
${
name?
word}
${
name:?
word}
In the first form, if name is set, or in the second form if name is both set and non-null, then substitute its value; otherwise, print word and exit from the shell. Interactive shells instead return to the prompt. If word is omitted, then a standard message is printed.
In any of the above expressions that test a variable and substitute an
alternate word, note that you can use standard shell quoting in the
word value to selectively override the splitting done by the
SH_WORD_SPLIT
option and the =
flag, but not splitting by the
s:
string:
flag.
In the following expressions, when name is an array and
the substitution is not quoted, or if the ‘(@)
’ flag or the
name[@]
syntax is used, matching and replacement is
performed on each array element separately.
${
name#
pattern}
${
name##
pattern}
If the pattern matches the beginning of the value of name, then substitute the value of name with the matched portion deleted; otherwise, just substitute the value of name. In the first form, the smallest matching pattern is preferred; in the second form, the largest matching pattern is preferred.
${
name%
pattern}
${
name%%
pattern}
If the pattern matches the end of the value of name, then substitute the value of name with the matched portion deleted; otherwise, just substitute the value of name. In the first form, the smallest matching pattern is preferred; in the second form, the largest matching pattern is preferred.
${
name:#
pattern}
If the pattern matches the value of name, then substitute
the empty string; otherwise, just substitute the value of name.
If name is an array
the matching array elements are removed (use the ‘(M)
’ flag to
remove the non-matched elements).
${
name:|
arrayname}
If arrayname is the name (N.B., not contents) of an array variable, then any elements contained in arrayname are removed from the substitution of name. If the substitution is scalar, either because name is a scalar variable or the expression is quoted, the elements of arrayname are instead tested against the entire expression.
${
name:*
arrayname}
Similar to the preceding substitution, but in the opposite sense, so that entries present in both the original substitution and as elements of arrayname are retained and others removed.
${
name:^
arrayname}
${
name:^^
arrayname}
Zips two arrays, such that the output array is twice as long as the
shortest (longest for ‘:^^
’) of name
and arrayname
, with
the elements alternatingly being picked from them. For ‘:^
’, if one
of the input arrays is longer, the output will stop when the end of the
shorter array is reached. Thus,
a=(1 2 3 4); b=(a b); print ${a:^b}
will output ‘1 a 2 b
’. For ‘:^^
’, then the input is repeated
until all of the longer array has been used up and the above will output
‘1 a 2 b 3 a 4 b
’.
Either or both inputs may be a scalar, they will be treated as an array of length 1 with the scalar as the only element. If either array is empty, the other array is output with no extra elements inserted.
Currently the following code will output ‘a b
’ and ‘1
’ as two separate
elements, which can be unexpected. The second print provides a workaround which
should continue to work if this is changed.
a=(a b); b=(1 2); print -l "${a:^b}"; print -l "${${a:^b}}"
${
name:
offset}
${
name:
offset:
length}
This syntax gives effects similar to parameter subscripting
in the form $
name[
start,
end]
, but is
compatible with other shells; note that both offset and length
are interpreted differently from the components of a subscript.
If offset is non-negative, then if the variable name is a scalar substitute the contents starting offset characters from the first character of the string, and if name is an array substitute elements starting offset elements from the first element. If length is given, substitute that many characters or elements, otherwise the entire rest of the scalar or array.
A positive offset is always treated as the offset of a character or
element in name from the first character or element of the array
(this is different from native zsh subscript notation). Hence 0
refers to the first character or element regardless of the setting of
the option KSH_ARRAYS
.
A negative offset counts backwards from the end of the scalar or array, so that -1 corresponds to the last character or element, and so on.
When positive, length counts from the offset position toward the end of the scalar or array. When negative, length counts back from the end. If this results in a position smaller than offset, a diagnostic is printed and nothing is substituted.
The option MULTIBYTE
is obeyed, i.e. the offset and length
count multibyte characters where appropriate.
offset and length undergo the same set of shell substitutions as for scalar assignment; in addition, they are then subject to arithmetic evaluation. Hence, for example
print ${foo:3} print ${foo: 1 + 2} print ${foo:$(( 1 + 2))} print ${foo:$(echo 1 + 2)}
all have the same effect, extracting the string starting at the fourth
character of $foo
if the substitution would otherwise return a scalar,
or the array starting at the fourth element if $foo
would return an
array. Note that with the option KSH_ARRAYS
$foo
always returns
a scalar (regardless of the use of the offset syntax) and a form
such as ${foo[*]:3}
is required to extract elements of an array named
foo
.
If offset is negative, the -
may not appear immediately
after the :
as this indicates the
${
name:-
word}
form of substitution. Instead, a space
may be inserted before the -
. Furthermore, neither offset nor
length may begin with an alphabetic character or &
as these are
used to indicate history-style modifiers. To substitute a value from a
variable, the recommended approach is to precede it with a $
as this
signifies the intention (parameter substitution can easily be rendered
unreadable); however, as arithmetic substitution is performed, the
expression ${var: offs}
does work, retrieving the offset from
$offs
.
For further compatibility with other shells there is a special case
for array offset 0. This usually accesses the
first element of the array. However, if the substitution refers to the
positional parameter array, e.g. $@
or $*
, then offset 0
instead refers to $0
, offset 1 refers to $1
, and so on. In
other words, the positional parameter array is effectively extended by
prepending $0
. Hence ${*:0:1}
substitutes $0
and
${*:1:1}
substitutes $1
.
${
name/
pattern/
repl}
${
name//
pattern/
repl}
${
name:/
pattern/
repl}
Replace the longest possible match of pattern in the expansion of
parameter name by string repl. The first form
replaces just the first occurrence, the second form all occurrences,
and the third form replaces only if pattern matches the entire string.
Both pattern and repl are subject to double-quoted substitution,
so that expressions like ${name/$opat/$npat}
will work, but obey the
usual rule that pattern characters in $opat
are not treated specially
unless either the option GLOB_SUBST
is set, or $opat
is instead
substituted as ${~opat}
.
The pattern may begin with a ‘#
’, in which case the
pattern must match at the start of the string, or ‘%
’, in
which case it must match at the end of the string, or ‘#%
’ in which
case the pattern must match the entire string. The repl may
be an empty string, in which case the final ‘/
’ may also be omitted.
To quote the final ‘/
’ in other cases it should be preceded by a
single backslash; this is not necessary if the
‘/
’ occurs inside a substituted parameter. Note also that the ‘#
’,
‘%
’ and ‘#%
are not active if they occur inside a substituted
parameter, even at the start.
If, after quoting rules apply, ${
name}
expands to an array,
the replacements act on each element individually. Note also the
effect of the I
and S
parameter expansion flags below; however,
the flags M
, R
, B
, E
and N
are not useful.
For example,
foo="twinkle twinkle little star" sub="t*e" rep="spy" print ${foo//${~sub}/$rep} print ${(S)foo//${~sub}/$rep}
Here, the ‘~
’ ensures that the text of $sub
is treated as a
pattern rather than a plain string. In the first case, the longest
match for t*e
is substituted and the result is ‘spy star
’,
while in the second case, the shortest matches are taken and the
result is ‘spy spy lispy star
’.
${#
spec}
If spec is one of the above substitutions, substitute
the length in characters of the result instead of
the result itself. If spec is an array expression,
substitute the number of elements of the result.
This has the side-effect that joining is skipped even in quoted
forms, which may affect other sub-expressions in spec.
Note that ‘^
’, ‘=
’, and ‘~
’, below, must appear
to the left of ‘#
’ when these forms are combined.
If the option POSIX_IDENTIFIERS
is not set, and spec is a
simple name, then the braces are optional; this is true even
for special parameters so e.g. $#-
and $#*
take the length
of the string $-
and the array $*
respectively. If
POSIX_IDENTIFIERS
is set, then braces are required for
the #
to be treated in this fashion.
${^
spec}
¶${^^
spec}
Turn on the RC_EXPAND_PARAM
option for the
evaluation of spec; if the ‘^
’ is doubled, turn it off.
When this option is set, array expansions of the form
foo${
xx}
bar,
where the parameter xx
is set to (
a b c)
, are substituted with
‘fooabar foobbar foocbar’ instead of the default
‘fooa b cbar’. Note that an empty array will therefore cause
all arguments to be removed.
Internally, each such expansion is converted into the
equivalent list for brace expansion. E.g., ${^var}
becomes
{$var[1],$var[2],
...}
, and is processed as described in
Brace Expansion below: note, however, the expansion
happens immediately, with any explicit brace expansion
happening later. If word splitting is also in effect the
$var[
N]
may themselves be split into different list
elements.
${=
spec}
¶${==
spec}
Perform word splitting using the rules for SH_WORD_SPLIT
during the
evaluation of spec, but regardless of whether the parameter appears in
double quotes; if the ‘=
’ is doubled, turn it off.
This forces parameter expansions to be split into
separate words before substitution, using IFS
as a delimiter.
This is done by default in most other shells.
Note that splitting is applied to word in the assignment forms
of spec before the assignment to name is performed.
This affects the result of array assignments with the A
flag.
${~
spec}
¶${~~
spec}
Turn on the GLOB_SUBST
option for the evaluation of
spec; if the ‘~
’ is doubled, turn it off. When this option is
set, the string resulting from the expansion will be interpreted as a
pattern anywhere that is possible, such as in filename expansion and
filename generation and pattern-matching contexts like the right
hand side of the ‘=
’ and ‘!=
’ operators in conditions.
In nested substitutions, note that the effect of the ~
applies to the
result of the current level of substitution. A surrounding pattern
operation on the result may cancel it. Hence, for example, if the
parameter foo
is set to *
, ${~foo//\*/*.c}
is substituted by
the pattern *.c
, which may be expanded by filename generation, but
${${~foo}//\*/*.c}
substitutes to the string *.c
, which will not
be further expanded.
If a ${
...}
type parameter expression or a
$(
...)
type command substitution is used in place of
name above, it is expanded first and the result is used as if
it were the value of name. Thus it is
possible to perform nested operations: ${${foo#head}%tail}
substitutes the value of $foo
with both ‘head
’ and ‘tail
’
deleted. The form with $(
...)
is often useful in
combination with the flags described next; see the examples below.
Each name or nested ${
...}
in a parameter expansion may
also be followed by a subscript expression as described in
Array Parameters.
Note that double quotes may appear around nested expressions, in which
case only the part inside is treated as quoted; for example,
${(f)"$(foo)"}
quotes the result of $(foo)
, but the flag ‘(f)
’
(see below) is applied using the rules for unquoted expansions. Note
further that quotes are themselves nested in this context; for example, in
"${(@f)"$(foo)"}"
, there are two sets of quotes, one surrounding the
whole expression, the other (redundant) surrounding the $(foo)
as
before.
If the opening brace is directly followed by an opening parenthesis,
the string up to the matching closing parenthesis will be taken as a
list of flags. In cases where repeating a flag is meaningful, the
repetitions need not be consecutive; for example, ‘(q%q%q
)’
means the same thing as the more readable ‘(%%qqq
)’. The
following flags are supported:
#
Evaluate the resulting words as numeric expressions and interpret
these as character codes. Output the corresponding characters. Note
that this form is entirely distinct from use of the #
without
parentheses.
If the MULTIBYTE
option is set and the number is greater than 127
(i.e. not an ASCII character) it is treated as a Unicode character.
%
Expand all %
escapes in the resulting words in the same way as in
prompts (see
Prompt Expansion). If this flag is given twice,
full prompt expansion is done on the resulting words, depending on the
setting of the PROMPT_PERCENT
, PROMPT_SUBST
and PROMPT_BANG
options.
@
In double quotes, array elements are put into separate words.
E.g., ‘"${(@)foo}"
’ is equivalent to ‘"${foo[@]}"
’ and
‘"${(@)foo[1,2]}"
’ is the same as ‘"$foo[1]" "$foo[2]"
’.
This is distinct from field splitting by the f
, s
or z
flags, which still applies within each array element.
A
Convert the substitution into an array expression, even if it otherwise
would be scalar. This has lower precedence than subscripting, so one
level of nested expansion is required in order that subscripts apply
to array elements. Thus ${${(A
)
name}[1]}
yields the full value of name when name is scalar.
This assigns an array parameter with ‘${
...=
...}
’,
‘${
...:=
...}
’ or ‘${
...::=
...}
’.
If this flag is repeated (as in ‘AA
’), assigns an associative
array parameter. Assignment is made before sorting or padding;
if field splitting is active, the word part is split before
assignment. The name part may be a subscripted range for
ordinary arrays; when assigning an associative array, the word
part must be converted to an array, for example by using
‘${(AA)=
name=
...}
’ to activate field splitting.
Surrounding context such as additional nesting or use of the value in a scalar assignment may cause the array to be joined back into a single string again.
a
Sort in array index order; when combined with ‘O
’ sort in reverse
array index order. Note that ‘a
’ is therefore equivalent to the
default but ‘Oa
’ is useful for obtaining an array’s elements in reverse
order.
b
Quote with backslashes only characters that are special to pattern
matching. This is useful when the contents of the variable are to be
tested using GLOB_SUBST
, including the ${~
...}
switch.
Quoting using one of the q
family of flags does not work
for this purpose since quotes are not stripped from non-pattern
characters by GLOB_SUBST
. In other words,
pattern=${(q)str} [[ $str = ${~pattern} ]]
works if $str
is ‘a*b
’ but not if it is ‘a b
’, whereas
pattern=${(b)str} [[ $str = ${~pattern} ]]
is always true for any possible value of $str
.
c
With ${#
name}
, count the total number of characters in an array,
as if the elements were concatenated with spaces between them. This is not
a true join of the array, so other expressions used with this flag may have
an effect on the elements of the array before it is counted.
C
Capitalize the resulting words. ‘Words’ in this case refers to sequences of alphanumeric characters separated by non-alphanumerics, not to words that result from field splitting.
D
Assume the string or array elements contain directories and attempt
to substitute the leading part of these by names. The remainder of
the path (the whole of it if the leading part was not substituted)
is then quoted so that the whole string can be used as a shell
argument. This is the reverse of ‘~
’ substitution: see
Filename Expansion.
e
Perform single word shell expansions, namely parameter expansion, command substitution and arithmetic expansion, on the result. Such expansions can be nested but too deep recursion may have unpredictable effects.
f
Split the result of the expansion at newlines. This is a shorthand
for ‘ps:\n:
’.
F
Join the words of arrays together using newline as a separator.
This is a shorthand for ‘pj:\n:
’.
g:
opts:
Process escape sequences like the echo builtin when no options are given
(g::
). With the o
option, octal escapes don’t take a leading
zero. With the c
option, sequences like ‘^X
’ are also processed.
With the e
option, processes ‘\M-t
’ and similar sequences like the
print builtin. With both of the o
and e
options, behaves like the
print builtin except that in none of these modes is ‘\c
’ interpreted.
i
Sort case-insensitively. May be combined with ‘n
’ or ‘O
’.
k
If name refers to an associative array, substitute the keys
(element names) rather than the values of the elements. Used with
subscripts (including ordinary arrays), force indices or keys to be
substituted even if the subscript form refers to values. However,
this flag may not be combined with subscript ranges. With the
KSH_ARRAYS
option a subscript ‘[*]
’ or ‘[@]
’ is needed
to operate on the whole array, as usual.
L
Convert all letters in the result to lower case.
n
Sort decimal integers numerically; if the first differing
characters of two test strings are not digits, sorting
is lexical. ‘+
’ and ‘-
’ are not treated specially; they are treated as
any other non-digit. Integers with more initial zeroes
are sorted before those with fewer or none. Hence the array ‘foo+24 foo1 foo02
foo2 foo3 foo20 foo23
’ is sorted into the order shown.
May be combined with ‘i
’ or ‘O
’.
-
As n
, but a leading minus sign indicates a negative decimal
integer. A leading minus sign not followed by an integer does not trigger
numeric sorting.
Note that ‘+
’ signs are not handled specially (this may change in the
future).
o
Sort the resulting words in ascending order; if this appears on its
own the sorting is lexical and case-sensitive (unless the locale
renders it case-insensitive). Sorting in ascending order is the
default for other forms of sorting, so this is ignored if combined
with ‘a
’, ‘i
’, ‘n
’ or ‘-
’.
O
Sort the resulting words in descending order; ‘O
’ without ‘a
’,
‘i
’, ‘n
’ or ‘-
’ sorts in reverse lexical order. May be
combined with ‘a
’, ‘i
’, ‘n
’ or ‘-
’ to reverse the
order of sorting.
P
This forces the value of the parameter name to be interpreted as a
further parameter name, whose value will be used where appropriate.
Note that flags set with one of the typeset
family of commands
(in particular case transformations) are not applied to the value of
name used in this fashion.
If used with a nested parameter or command substitution, the result of that
will be taken as a parameter name in the same way. For example, if you
have ‘foo=bar
’ and ‘bar=baz
’, the strings ${(P)foo}
,
${(P)${foo}}
, and ${(P)$(echo bar)}
will be expanded to
‘baz
’.
Likewise, if the reference is itself nested, the expression with the
flag is treated as if it were directly replaced by the parameter name.
It is an error if this nested substitution produces an array with more
than one word. For example, if ‘name=assoc
’ where the parameter
assoc
is an associative array, then
‘${${(P)name}[elt]}
’ refers to the element of the associative
subscripted ‘elt
’.
q
Quote characters that are special to the shell in the resulting words with
backslashes; unprintable or invalid characters are quoted using the
$'\
NNN'
form, with separate quotes for each octet.
If this flag is given twice, the resulting words are quoted in single
quotes and if it is given three times, the words are quoted in double
quotes; in these forms no special handling of unprintable or invalid
characters is attempted. If the flag is given four times, the words are
quoted in single quotes preceded by a $
. Note that in all three of
these forms quoting is done unconditionally, even if this does not change
the way the resulting string would be interpreted by the shell.
If a q-
is given (only a single q
may appear), a minimal
form of single quoting is used that only quotes the string if needed to
protect special characters. Typically this form gives the most readable
output.
If a q+
is given, an extended form of minimal quoting is used that
causes unprintable characters to be rendered using $'
...'
.
This quoting is similar to that used by the output of values by the
typeset
family of commands.
Q
Remove one level of quotes from the resulting words.
t
Use a string describing the type of the parameter where the value
of the parameter would usually appear. This string consists of keywords
separated by hyphens (‘-
’). The first keyword in the string describes
the main type, it can be one of ‘scalar
’, ‘array
’, ‘integer
’,
‘float
’ or ‘association
’. The other keywords describe the type in
more detail:
local
for local parameters
left
for left justified parameters
right_blanks
for right justified parameters with leading blanks
right_zeros
for right justified parameters with leading zeros
lower
for parameters whose value is converted to all lower case when it is expanded
upper
for parameters whose value is converted to all upper case when it is expanded
readonly
for readonly parameters
tag
for tagged parameters
tied
for parameters tied to another parameter in the manner of PATH
(colon-separated list) and path
(array), whether these are
special parameters or user-defined with ‘typeset -T
’
export
for exported parameters
unique
for arrays which keep only the first occurrence of duplicated values
hide
for parameters with the ‘hide’ flag
hideval
for parameters with the ‘hideval’ flag
special
for special parameters defined by the shell
u
Expand only the first occurrence of each unique word.
U
Convert all letters in the result to upper case.
v
Used with k
, substitute (as two consecutive words) both the key
and the value of each associative array element. Used with subscripts,
force values to be substituted even if the subscript form refers to
indices or keys.
V
Make any special characters in the resulting words visible.
w
With ${#
name}
, count words in arrays or strings; the s
flag may be used to set a word delimiter.
W
Similar to w
with the difference that empty words between
repeated delimiters are also counted.
X
With this flag, parsing errors occurring with the Q
, e
and #
flags or the pattern matching forms such as
‘${
name#
pattern}
’ are reported. Without the flag,
errors are silently ignored.
z
Split the result of the expansion into words using shell parsing to
find the words, i.e. taking into account any quoting in the value.
Comments are not treated specially but as ordinary strings, similar
to interactive shells with the INTERACTIVE_COMMENTS
option unset
(however, see the Z
flag below for related options)
Note that this is done very late, even later than the ‘(s)
’ flag. So to
access single words in the result use nested expansions as
in ‘${${(z)foo}[2]}
’. Likewise, to remove the quotes in the
resulting words use ‘${(Q)${(z)foo}}
’.
0
Split the result of the expansion on null bytes. This is a shorthand
for ‘ps:\0:
’.
The following flags (except p
) are followed by one or more arguments
as shown. Any character, or the matching pairs ‘(
...)
’,
‘{
...}
’, ‘[
...]
’, or ‘<
...>
’, may be used in place
of a colon as delimiters, but note that when a flag takes more than one
argument, a matched pair of delimiters must surround each argument.
p
Recognize the same escape sequences as the print
builtin
in string arguments to any of the flags described below that
follow this argument.
Alternatively, with this option string arguments may be in the form
$
var in which case the value of the variable is substituted.
Note this form is strict; the string argument does not undergo general
parameter expansion.
For example,
sep=: val=a:b:c print ${(ps.$sep.)val}
splits the variable on a :
.
~
Strings inserted into the expansion by any of the flags below are to
be treated as patterns. This applies to the string arguments of flags
that follow ~
within the same set of parentheses. Compare with ~
outside parentheses, which forces the entire substituted string to
be treated as a pattern. Hence, for example,
[[ "?" = ${(~j.|.)array} ]]
treats ‘|
’ as a pattern and succeeds if and only if $array
contains the string ‘?
’ as an element. The ~
may be
repeated to toggle the behaviour; its effect only lasts to the
end of the parenthesised group.
j:
string:
Join the words of arrays together using string as a separator.
Note that this occurs before field splitting by the s:
string:
flag or the SH_WORD_SPLIT
option.
l:
expr::
string1::
string2:
Pad the resulting words on the left. Each word will be truncated if required and placed in a field expr characters wide.
The arguments :
string1:
and :
string2:
are
optional; neither, the first, or both may be given. Note that the same
pairs of delimiters must be used for each of the three arguments. The
space to the left will be filled with string1 (concatenated as
often as needed) or spaces if string1 is not given. If both
string1 and string2 are given, string2 is inserted once
directly to the left of each word, truncated if necessary, before
string1 is used to produce any remaining padding.
If either of string1 or string2 is present but empty,
i.e. there are two delimiters together at that point, the first
character of $IFS
is used instead.
If the MULTIBYTE
option is in effect, the flag m
may also
be given, in which case widths will be used for the calculation of
padding; otherwise individual multibyte characters are treated as occupying
one unit of width.
If the MULTIBYTE
option is not in effect, each byte in the string is
treated as occupying one unit of width.
Control characters are always assumed to be one unit wide; this allows the mechanism to be used for generating repetitions of control characters.
m
Only useful together with one of the flags l
or r
or with the
#
length operator when the MULTIBYTE
option
is in effect. Use the character width reported by the system in
calculating how much of the string it occupies or the overall
length of the string. Most printable characters have a width of one
unit, however certain Asian character sets and certain special effects
use wider characters; combining characters have zero width.
Non-printable characters are arbitrarily counted as zero width; how they
would actually be displayed will vary.
If the m
is repeated, the character either counts zero (if it has
zero width), else one. For printable character strings this has the
effect of counting the number of glyphs (visibly separate characters),
except for the case where combining characters themselves have non-zero
width (true in certain alphabets).
r:
expr::
string1::
string2:
As l
, but pad the words on the right and insert string2
immediately to the right of the string to be padded.
Left and right padding may be used together. In this case the strategy is to apply left padding to the first half width of each of the resulting words, and right padding to the second half. If the string to be padded has odd width the extra padding is applied on the left.
s:
string:
Force field splitting at the
separator string. Note that a string of two or more
characters means that all of them must match in sequence; this differs from
the treatment of two or more characters in the IFS
parameter.
See also the =
flag and the SH_WORD_SPLIT
option. An empty
string may also be given in which case every character will be a separate
element.
For historical reasons, the usual behaviour that empty array elements are retained inside double quotes is disabled for arrays generated by splitting; hence the following:
line="one::three" print -l "${(s.:.)line}"
produces two lines of output for one
and three
and elides the
empty field. To override this behaviour, supply the ‘(@)
’ flag as well,
i.e. "${(@s.:.)line}"
.
Z:
opts:
As z
but takes a combination of option letters between a following
pair of delimiter characters. With no options the effect is identical
to z
. The following options are available:
(Z+c+)
causes comments to be parsed as a string and retained; any field in the resulting array beginning with an unquoted comment character is a comment.
(Z+C+)
causes comments to be parsed
and removed. The rule for comments is standard: anything between a word
starting with the third character of $HISTCHARS
, default #
, up to
the next newline is a comment.
(Z+n+)
causes unquoted newlines to be treated as ordinary whitespace, else they are treated as if they are shell code delimiters and converted to semicolons.
Options are combined within the same set of delimiters,
e.g. (Z+Cn+)
.
_:
flags:
The underscore (_
) flag is reserved for future use. As of this
revision of zsh, there are no valid flags; anything following an
underscore, other than an empty pair of delimiters, is treated as an
error, and the flag itself has no effect.
The following flags are meaningful with the ${
...#
...}
or
${
...%
...}
forms. The S
, I
, and *
flags may also be
used with the ${
.../
...}
forms.
S
With #
or ##
, search for the match that starts closest to the start of
the string (a ‘substring match’). Of all matches at a particular position,
#
selects the shortest and ##
the longest:
% str="aXbXc" % echo ${(S)str#X*} abXc % echo ${(S)str##X*} a %
With %
or %%
, search for the match that starts closest to the end of
the string:
% str="aXbXc" % echo ${(S)str%X*} aXbc % echo ${(S)str%%X*} aXb %
(Note that %
and %%
don’t search for the match that ends closest to the
end of the string, as one might expect.)
With substitution via ${
.../
...}
or
${
...//
...}
, specifies non-greedy matching, i.e. that the
shortest instead of the longest match should be replaced:
% str="abab" % echo ${str/*b/_} _ % echo ${(S)str/*b/_} _ab %
I:
expr:
Search the exprth match (where expr evaluates to a number).
This only applies when searching for substrings, either with the S
flag, or with ${
.../
...}
(only the exprth match is
substituted) or ${
...//
...}
(all matches from the
exprth on are substituted). The default is to take the first match.
The exprth match is counted such that there is either one or zero
matches from each starting position in the string, although for global
substitution matches overlapping previous replacements are ignored. With
the ${
...%
...}
and ${
...%%
...}
forms, the starting
position for the match moves backwards from the end as the index increases,
while with the other forms it moves forward from the start.
Hence with the string
which switch is the right switch for Ipswich?
substitutions of the form
${
(SI:
N:
)string#w*ch}
as N increases
from 1 will match and remove ‘which
’, ‘witch
’, ‘witch
’ and
‘wich
’; the form using ‘##
’ will match and remove ‘which switch
is the right switch for Ipswich
’, ‘witch is the right switch for
Ipswich
’, ‘witch for Ipswich
’ and ‘wich
’. The form using ‘%
’
will remove the same matches as for ‘#
’, but in reverse order, and the
form using ‘%%
’ will remove the same matches as for ‘##
’ in reverse
order.
*
¶Enable EXTENDED_GLOB
for substitution via ${
.../
...}
or
${
...//
...}
. Note that ‘**
’ does not disable extendedglob.
B
Include the index of the beginning of the match in the result.
E
Include the index one character past the end of the match in the result (note this is inconsistent with other uses of parameter index).
M
Include the matched portion in the result.
N
Include the length of the match in the result.
R
Include the unmatched portion in the result (the Rest).
Here is a summary of the rules for substitution; this assumes that braces
are present around the substitution, i.e. ${
...}
. Some particular
examples are given below. Note that the Zsh Development Group accepts
no responsibility for any brain damage which may occur during the
reading of the following rules.
1.
Nested substitutionIf multiple nested ${
...}
forms are present, substitution is
performed from the inside outwards. At each level, the substitution takes
account of whether the current value is a scalar or an array, whether the
whole substitution is in double quotes, and what flags are supplied to the
current level of substitution, just as if the nested substitution were the
outermost. The flags are not propagated up to enclosing
substitutions; the nested substitution will return either a scalar or an
array as determined by the flags, possibly adjusted for quoting. All the
following steps take place where applicable at all levels of substitution.
Note that, unless the ‘(P)
’ flag is present, the flags and any
subscripts apply directly to the value of the nested substitution; for
example, the expansion ${${foo}}
behaves exactly the same as
${foo}
. When the ‘(P)
’ flag is present in a nested substitution,
the other substitution rules are applied to the value before it is
interpreted as a name, so ${${(P)foo}}
may differ from ${(P)foo}
.
At each nested level of substitution, the substituted words undergo all
forms of single-word substitution (i.e. not filename generation), including
command substitution, arithmetic expansion and filename expansion
(i.e. leading ~
and =
). Thus, for example, ${${:-=cat}:h}
expands to the directory where the cat
program resides. (Explanation:
the internal substitution has no parameter but a default value =cat
,
which is expanded by filename expansion to a full path; the outer
substitution then applies the modifier :h
and takes the directory part
of the path.)
2.
Internal parameter flagsAny parameter flags set by one of the typeset
family of commands, in
particular the -L
, -R
, -Z
, -u
and -l
options for
padding and capitalization, are applied directly to the parameter value.
Note these flags are options to the command, e.g. ‘typeset -Z
’; they
are not the same as the flags used within parameter substitutions.
At the outermost level of substitution, the ‘(P)
’ flag (rule 4.
)
ignores these transformations and uses the unmodified value of the
parameter as the name to be replaced. This is usually the desired
behavior because padding may make the value syntactically illegal as a
parameter name, but if capitalization changes are desired, use the
${${(P)foo}}
form (rule 25.
).
3.
Parameter subscriptingIf the value is a raw parameter reference with a subscript, such as
${
var[3]}
, the effect of subscripting is applied directly to
the parameter. Subscripts are evaluated left to right; subsequent
subscripts apply to the scalar or array value yielded by the previous
subscript. Thus if var
is an array, ${var[1][2]}
is the second
character of the first word, but ${var[2,4][2]}
is the entire third
word (the second word of the range of words two through four of the
original array). Any number of subscripts may appear. Flags such as
‘(k)
’ and ‘(v)
’ which alter the result of subscripting are applied.
4.
Parameter name replacementAt the outermost level of nesting only, the ‘(P)
’ flag is applied. This
treats the value so far as a parameter name (which may include a subscript
expression) and replaces that with the corresponding value. This
replacement occurs later if the ‘(P)
’ flag appears in a nested
substitution.
If the value so far names a parameter that has internal flags (rule 2.
),
those internal flags are applied to the new value after replacement.
5.
Double-quoted joiningIf the value after this process is an array, and the substitution
appears in double quotes, and neither an ‘(@)
’ flag nor a ‘#
’
length operator is present at the current level, then words of the
value are joined with the first character of the parameter $IFS
,
by default a space, between each word (single word arrays are not
modified). If the ‘(j)
’ flag is present, that is used for joining
instead of $IFS
.
6.
Nested subscriptingAny remaining subscripts (i.e. of a nested substitution) are evaluated at
this point, based on whether the value is an array or a scalar. As with
3.
, multiple subscripts can appear. Note that ${foo[2,4][2]}
is
thus equivalent to ${${foo[2,4]}[2]}
and also to
"${${(@)foo[2,4]}[2]}"
(the nested substitution returns an array in
both cases), but not to "${${foo[2,4]}[2]}"
(the nested substitution
returns a scalar because of the quotes).
7.
ModifiersAny modifiers, as specified by a trailing ‘#
’, ‘%
’, ‘/
’
(possibly doubled) or by a set of modifiers of the form ‘:...
’ (see
Modifiers in History Expansion), are applied to the words
of the value at this level.
8.
Character evaluationAny ‘(#)
’ flag is applied, evaluating the result so far numerically
as a character.
9.
LengthAny initial ‘#
’ modifier, i.e. in the form ${#
var}
, is
used to evaluate the length of the expression so far.
10.
Forced joiningIf the ‘(j)
’ flag is present, or no ‘(j)
’ flag is present but
the string is to be split as given by rule 11.
, and joining
did not take place at rule 5.
, any words in the value are joined
together using the given string or the first character of $IFS
if none.
Note that the ‘(F)
’ flag implicitly supplies a string for joining in this
manner.
11.
Simple word splittingIf one of the ‘(s)
’ or ‘(f)
’ flags are present, or the ‘=
’
specifier was present (e.g. ${=
var}
), the word is split on
occurrences of the specified string, or (for =
with neither of the two
flags present) any of the characters in $IFS
.
If no ‘(s)
’, ‘(f)
’ or ‘=
’ was given, but the word is not
quoted and the option SH_WORD_SPLIT
is set, the word is split on
occurrences of any of the characters in $IFS
. Note this step, too,
takes place at all levels of a nested substitution.
12.
Case modificationAny case modification from one of the flags ‘(L)
’, ‘(U)
’ or ‘(C)
’
is applied.
13.
Escape sequence replacementFirst any replacements from the ‘(g)
’ flag are performed, then any
prompt-style formatting from the ‘(%)
’ family of flags is applied.
14.
Quote applicationAny quoting or unquoting using ‘(q)
’ and ‘(Q)
’ and related flags
is applied.
15.
Directory namingAny directory name substitution using ‘(D)
’ flag is applied.
16.
Visibility enhancementAny modifications to make characters visible using the ‘(V)
’ flag
are applied.
17.
Lexical word splittingIf the ’(z)
’ flag or one of the forms of the ’(Z)
’ flag is
present, the word is split as if it were a shell command line, so that
quotation marks and other metacharacters are used to decide what
constitutes a word. Note this form of splitting is entirely distinct
from that described by rule 11.
: it does not use $IFS
, and
does not cause forced joining.
18.
UniquenessIf the result is an array and the ‘(u)
’ flag was present, duplicate
elements are removed from the array.
19.
OrderingIf the result is still an array and one of the ‘(o)
’ or ‘(O)
’ flags
was present, the array is reordered.
20.
RC_EXPAND_PARAM
At this point the decision is made whether any resulting array elements
are to be combined element by element with surrounding text, as given
by either the RC_EXPAND_PARAM
option or the ‘^
’ flag.
21.
Re-evaluationAny ‘(e)
’ flag is applied to the value, forcing it to be re-examined
for new parameter substitutions, but also for command and arithmetic
substitutions.
22.
PaddingAny padding of the value by the ‘(l.
fill.)
’ or
‘(r.
fill.)
’ flags is applied.
23.
Semantic joiningIn contexts where expansion semantics requires a single word to
result, all words are rejoined with the first character of IFS
between. So in ‘${(P
)${(f
)lines}}
’
the value of ${lines}
is split at newlines, but then must be
joined again before the ‘(P)
’ flag can be applied.
If a single word is not required, this rule is skipped.
24.
Empty argument removalIf the substitution does not appear in double quotes, any resulting zero-length argument, whether from a scalar or an element of an array, is elided from the list of arguments inserted into the command line.
Strictly speaking, the removal happens later as the same happens with other forms of substitution; the point to note here is simply that it occurs after any of the above parameter operations.
25.
Nested parameter name replacementIf the ‘(P)
’ flag is present and rule 4.
has not applied, the
value so far is treated as a parameter name (which may include a subscript
expression) and replaced with the corresponding value, with internal flags
(rule 2.
) applied to the new value.
The flag f
is useful to split a double-quoted substitution line by
line. For example, ${(f)"$(<
file)"}
substitutes the contents of file divided so that each line is
an element of the resulting array. Compare this with the effect of
$
(<
file)
alone, which divides the file
up by words, or the same inside double quotes, which makes the entire
content of the file a single string.
The following illustrates the rules for nested parameter expansions.
Suppose that $foo
contains the array (bar baz
)
:
"${(@)${foo}[1]}"
This produces the result b
. First, the inner substitution
"${foo}"
, which has no array (@
) flag, produces a single word
result "bar baz"
. The outer substitution "${(@)...[1]}"
detects
that this is a scalar, so that (despite the ‘(@)
’ flag) the subscript
picks the first character.
"${${(@)foo}[1]}"
This produces the result ‘bar
’. In this case, the inner substitution
"${(@)foo}"
produces the array ‘(bar baz
)
’. The outer
substitution "${...[1]}"
detects that this is an array and picks the
first word. This is similar to the simple case "${foo[1]}"
.
As an example of the rules for word splitting and joining, suppose $foo
contains the array ‘(ax1 bx1
)
’. Then
${(s/x/)foo}
produces the words ‘a
’, ‘1 b
’ and ‘1
’.
${(j/x/s/x/)foo}
produces ‘a
’, ‘1
’, ‘b
’ and ‘1
’.
${(s/x/)foo%%1*}
produces ‘a
’ and ‘ b
’ (note the extra space). As substitution
occurs before either joining or splitting, the operation first generates
the modified array (ax bx
)
, which is joined to give
"ax bx"
, and then split to give ‘a
’, ‘ b
’ and ‘’. The final
empty string will then be elided, as it is not in double quotes.
A command enclosed in parentheses preceded by a dollar sign, like
‘$(
...)
’, or quoted with grave
accents, like ‘`
...`
’, is replaced with its standard output, with
any trailing newlines deleted.
If the substitution is not enclosed in double quotes, the
output is broken into words using the IFS
parameter.
The substitution ‘$(cat
foo)
’ may be replaced
by the faster ‘$(<
foo)
’. In this case foo
undergoes single word shell expansions (parameter expansion,
command substitution and arithmetic expansion), but not
filename generation.
If the option GLOB_SUBST
is set, the result of any unquoted command
substitution, including the special form just mentioned, is eligible for
filename generation.
A string of the form ‘$[
exp]
’ or
‘$((
exp))
’ is substituted
with the value of the arithmetic expression exp. exp is
subjected to parameter expansion, command substitution
and arithmetic expansion before it is evaluated.
See Arithmetic Evaluation.
A string of the form
‘foo{
xx,
yy,
zz}
bar’
is expanded to the individual words
‘fooxxbar’, ‘fooyybar’ and ‘foozzbar’.
Left-to-right order is preserved. This construct
may be nested. Commas may be quoted in order to
include them literally in a word.
An expression of the form ‘{
n1..
n2}
’,
where n1 and n2 are integers,
is expanded to every number between
n1 and n2 inclusive. If either number begins with a
zero, all the resulting numbers will be padded with leading zeroes to
that minimum width, but for negative numbers the -
character is also
included in the width. If the numbers are in decreasing order the
resulting sequence will also be in decreasing order.
An expression of the form ‘{
n1..
n2..
n3}
’,
where n1, n2, and n3 are integers,
is expanded as above, but only every n3th number starting from n1
is output. If n3 is negative the numbers are output in reverse order,
this is slightly different from simply swapping n1 and n2 in the case
that the step n3 doesn’t evenly divide the range. Zero padding can be
specified in any of the three numbers, specifying it in the third can be useful
to pad for example ‘{-99..100..01}
’ which is not possible to specify by putting a
0 on either of the first two numbers (i.e. pad to two characters).
An expression of the form ‘{
c1..
c2}
’, where
c1 and c2 are single characters (which may be multibyte
characters), is expanded to every character in the range from c1 to
c2 in whatever character sequence is used internally. For
characters with code points below 128 this is US ASCII (this is the only
case most users will need). If any intervening character is not
printable, appropriate quotation is used to render it printable.
If the character sequence is reversed, the output is in reverse
order, e.g. ‘{d..a}
’ is substituted as ‘d c b a
’.
If a brace expression matches none of the above forms, it is left
unchanged, unless the option BRACE_CCL
(an abbreviation for ‘brace
character class’) is set.
In that case, it is expanded to a list of the individual
characters between the braces sorted into the order of the characters
in the ASCII character set (multibyte characters are not currently
handled). The syntax is similar to a
[
...]
expression in filename generation:
‘-
’ is treated specially to denote a range of characters, but ‘^
’ or
‘!
’ as the first character is treated normally. For example,
‘{abcdef0-9}
’ expands to 16 words 0 1 2 3 4 5 6 7 8 9 a b c d e f
.
Note that brace expansion is not part of filename generation (globbing); an
expression such as */{foo,bar}
is split into two separate words
*/foo
and */bar
before filename generation takes place. In
particular, note that this is liable to produce a ‘no match’ error if
either of the two expressions does not match; this is to be contrasted
with */(foo|bar)
, which is treated as a single pattern but otherwise
has similar effects.
To combine brace expansion with array expansion, see the
${^
spec}
form described
in Parameter Expansion
above.
Each word is checked to see if it begins with an unquoted ‘~
’.
If it does, then the word up to a ‘/
’,
or the end of the word if there is no ‘/
’,
is checked to see if it can be substituted in one of the ways
described here. If so, then the ‘~
’ and the checked portion are
replaced with the appropriate substitute value.
A ‘~
’ by itself is replaced by the value of $HOME
.
A ‘~
’ followed by a ‘+
’ or a ‘-
’ is replaced by current
or previous working directory, respectively.
A ‘~
’ followed by a number is replaced by the directory at that
position in the directory stack.
‘~0
’ is equivalent to ‘~+
’,
and ‘~1
’ is the top of the stack.
‘~+
’ followed by a number is replaced by the directory at that
position in the directory stack.
‘~+0
’ is equivalent to ‘~+
’,
and ‘~+1
’ is the top of the stack.
‘~-
’ followed by a number is replaced by the directory that
many positions from the bottom of the stack.
‘~-0
’ is the bottom of the stack.
The PUSHD_MINUS
option exchanges the effects of ‘~+
’ and ‘~-
’ where they are
followed by a number.
If the function zsh_directory_name
exists, or the shell variable
zsh_directory_name_functions
exists and contains an array of
function names, then the functions are used to implement dynamic
directory naming. The functions are tried in order until one returns
status zero, so it is important that functions test whether they can
handle the case in question and return an appropriate status.
A ‘~
’ followed by a string namstr in unquoted square brackets is
treated specially as a dynamic directory name. Note that the first
unquoted closing square bracket always terminates namstr. The shell
function is passed two arguments: the string n
(for name) and
namstr. It should either set the array reply
to a single element
which is the directory corresponding to the name and return status zero
(executing an assignment as the last statement is usually sufficient), or
it should return status non-zero. In the former case the element of reply
is used as the directory; in the latter case the substitution is deemed to
have failed. If all functions fail and the option NOMATCH
is set,
an error results.
The functions defined as above are also used to see if a directory can
be turned into a name, for example when printing the directory stack or
when expanding %~
in prompts. In this case each function is passed two
arguments: the string d
(for directory) and the candidate for dynamic
naming. The function should either return non-zero status, if the
directory cannot be named by the function, or it should set the array reply
to consist of two elements: the first is the dynamic name for the directory
(as would appear within ‘~[
...]
’), and the second is the
prefix length of the directory to be replaced. For example, if the trial
directory is /home/myname/src/zsh
and the dynamic name for
/home/myname/src
(which has 16 characters) is s
, then the function
sets
reply=(s 16)
The directory name so returned is compared with possible static names for parts of the directory path, as described below; it is used if the prefix length matched (16 in the example) is longer than that matched by any static name.
It is not a requirement that a function implements both
n
and d
calls; for example, it might be appropriate for certain
dynamic forms of expansion not to be contracted to names. In that case
any call with the first argument d
should cause a non-zero status to
be returned.
The completion system calls ‘zsh_directory_name c
’ followed by
equivalent calls to elements of the array
zsh_directory_name_functions
, if it exists, in order to
complete dynamic names for directories. The code for this should be
as for any other completion function as described in
Completion System.
As a working example, here is a function that expands any dynamic names
beginning with the string p:
to directories below
/home/pws/perforce
. In this simple case a static name for the
directory would be just as effective.
zsh_directory_name() { emulate -L zsh setopt extendedglob local -a match mbegin mend if [[ $1 = d ]]; then # turn the directory into a name if [[ $2 = (#b)(/home/pws/perforce/)([^/]##)* ]]; then typeset -ga reply reply=(p:$match[2] $(( ${#match[1]} + ${#match[2]} )) ) else return 1 fi elif [[ $1 = n ]]; then # turn the name into a directory [[ $2 != (#b)p:(?*) ]] && return 1 typeset -ga reply reply=(/home/pws/perforce/$match[1]) elif [[ $1 = c ]]; then # complete names local expl local -a dirs dirs=(/home/pws/perforce/*(/:t)) dirs=(p:${^dirs}) _wanted dynamic-dirs expl 'dynamic directory' compadd -S\] -a dirs return else return 1 fi return 0 }
A ‘~
’ followed by anything not already covered consisting
of any number of alphanumeric characters or underscore (‘_
’),
hyphen (‘-
’), or dot (‘.
’) is looked up as a
named directory, and replaced by the value of that named directory if found.
Named directories are typically home directories for users on the system.
They may also be defined if the text after the ‘~
’ is the name
of a string shell parameter whose value begins with a ‘/
’.
Note that trailing slashes will be removed from the path to the directory
(though the original parameter is not modified).
It is also possible to define directory names using the -d
option to the
hash
builtin.
When the shell prints a path (e.g. when expanding %~
in prompts or when
printing the directory stack), the path is checked to see if it has a named
directory as its prefix. If so, then the prefix portion is replaced with a
‘~
’ followed by the name of the directory.
The shorter of the two ways of referring to the directory is used,
i.e. either the directory name or the full path; the name is used
if they are the same length.
The parameters $PWD
and $OLDPWD
are never abbreviated in this fashion.
If a word begins with an unquoted ‘=
’
and the EQUALS
option is set,
the remainder of the word is taken as the
name of a command. If a command
exists by that name, the word is replaced
by the full pathname of the command.
Filename expansion is performed on the right hand side of a parameter
assignment, including those appearing after commands of the
typeset
family. In this case, the right hand side will be treated
as a colon-separated list in the manner of the PATH
parameter,
so that a ‘~
’ or an ‘=
’ following a ‘:
’ is eligible for expansion.
All such behaviour can be
disabled by quoting the ‘~
’, the ‘=
’, or the whole expression (but not
simply the colon); the EQUALS
option is also respected.
If the option MAGIC_EQUAL_SUBST
is set, any unquoted shell
argument in the form ‘identifier=
expression’ becomes eligible
for file expansion as described in the previous paragraph. Quoting the
first ‘=
’ also inhibits this.
If a word contains an unquoted instance of one of the characters
‘*
’, ‘(
’, ‘|
’, ‘<
’, ‘[
’, or ‘?
’, it is regarded
as a pattern for filename generation, unless the GLOB
option is unset.
If the EXTENDED_GLOB
option is set,
the ‘^
’ and ‘#
’ characters also denote a pattern; otherwise
they are not treated specially by the shell.
The word is replaced with a list of sorted filenames that match
the pattern. If no matching pattern is found, the shell gives
an error message, unless the NULL_GLOB
option is set,
in which case the word is deleted; or unless the NOMATCH
option is unset, in which case the word is left unchanged.
In filename generation,
the character ‘/
’ must be matched explicitly;
also, a ‘.
’ must be matched
explicitly at the beginning of a pattern or after a ‘/
’, unless the
GLOB_DOTS
option is set.
No filename generation pattern
matches the files ‘.
’ or ‘..
’. In other instances of pattern
matching, the ‘/
’ and ‘.
’ are not treated specially.
*
Matches any string, including the null string.
?
Matches any character.
[
...]
Matches any of the enclosed characters. Ranges of characters
can be specified by separating two characters by a ‘-
’.
A ‘-
’ or ‘]
’ may be matched by including it as the
first character in the list.
There are also several named classes of characters, in the form
‘[:
name:]
’ with the following meanings.
The first set use the macros provided by
the operating system to test for the given character combinations,
including any modifications due to local language settings, see
ctype(3):
[:alnum:]
The character is alphanumeric
[:alpha:]
The character is alphabetic
[:ascii:]
The character is 7-bit, i.e. is a single-byte character without the top bit set.
[:blank:]
The character is a blank character
[:cntrl:]
The character is a control character
[:digit:]
The character is a decimal digit
[:graph:]
The character is a printable character other than whitespace
[:lower:]
The character is a lowercase letter
[:print:]
The character is printable
[:punct:]
The character is printable but neither alphanumeric nor whitespace
[:space:]
The character is whitespace
[:upper:]
The character is an uppercase letter
[:xdigit:]
The character is a hexadecimal digit
Another set of named classes is handled internally by the shell and is not sensitive to the locale:
[:IDENT:]
The character is allowed to form part of a shell identifier, such
as a parameter name; this test respects the POSIX_IDENTIFIERS
option
[:IFS:]
The character is used as an input field separator, i.e. is contained in the
IFS
parameter
[:IFSSPACE:]
The character is an IFS white space character; see the documentation
for IFS
in
Parameters Used By The Shell.
[:INCOMPLETE:]
Matches a byte that starts an incomplete multibyte character.
Note that there may be a sequence of more than one bytes that
taken together form the prefix of a multibyte character. To
test for a potentially incomplete byte sequence, use the pattern
‘[[:INCOMPLETE:]]*
’. This will never match a sequence starting
with a valid multibyte character.
[:INVALID:]
Matches a byte that does not start a valid multibyte character. Note this may be a continuation byte of an incomplete multibyte character as any part of a multibyte string consisting of invalid and incomplete multibyte characters is treated as single bytes.
[:WORD:]
The character is treated as part of a word; this test is sensitive
to the value of the WORDCHARS
parameter
Note that the square brackets are additional
to those enclosing the whole set of characters, so to test for a
single alphanumeric character you need ‘[[:alnum:]]
’. Named
character sets can be used alongside other types,
e.g. ‘[[:alpha:]0-9]
’.
[^
...]
[!
...]
Like [
...]
, except that it matches any character which is
not in the given set.
<
[x]-
[y]>
Matches any number in the range x to y, inclusive.
Either of the numbers may be omitted to make the range open-ended;
hence ‘<->
’ matches any number. To match individual digits, the
[
...]
form is more efficient.
Be careful when using other wildcards adjacent to patterns of this form;
for example, <0-9>*
will actually match any number whatsoever at the
start of the string, since the ‘<0-9>
’ will match the first digit, and
the ‘*
’ will match any others. This is a trap for the unwary, but is
in fact an inevitable consequence of the rule that the longest possible
match always succeeds. Expressions such as ‘<0-9>[^[:digit:]]*
’ can be
used instead.
(
...)
Matches the enclosed pattern. This is used for grouping.
If the KSH_GLOB
option is set, then a
‘@
’, ‘*
’, ‘+
’, ‘?
’ or ‘!
’ immediately preceding
the ‘(
’ is treated specially, as detailed below. The option
SH_GLOB
prevents bare parentheses from being used in this way, though
the KSH_GLOB
option is still available.
Note that grouping cannot extend over multiple directories: it is an error
to have a ‘/
’ within a group (this only applies for patterns used in
filename generation). There is one exception: a group of the form
(
pat/)#
appearing as a complete path segment can
match a sequence of directories. For example, foo/(a*/)#bar
matches
foo/bar
, foo/any/bar
, foo/any/anyother/bar
, and so on.
|
yMatches either x or y.
This operator has lower precedence than any other.
The ‘|
’ character
must be within parentheses, to avoid interpretation as a pipeline.
The alternatives are tried in order from left to right.
^
x(Requires EXTENDED_GLOB
to be set.)
Matches anything except the pattern x.
This has a higher precedence than ‘/
’, so ‘^foo/bar
’
will search directories in ‘.
’ except ‘./foo
’
for a file named ‘bar
’.
~
y(Requires EXTENDED_GLOB
to be set.)
Match anything that matches the pattern x but does not match y.
This has lower precedence than any operator except ‘|
’, so
‘*/*~foo/bar
’ will search for all files in all directories in ‘.
’
and then exclude ‘foo/bar
’ if there was such a match.
Multiple patterns can be excluded by
‘foo~
bar~
baz’.
In the exclusion pattern (y), ‘/
’ and ‘.
’ are not treated
specially the way they usually are in globbing.
#
(Requires EXTENDED_GLOB
to be set.)
Matches zero or more occurrences of the pattern x.
This operator has high precedence; ‘12#
’ is equivalent to ‘1(2#)
’,
rather than ‘(12)#
’. It is an error for an unquoted ‘#
’ to follow
something which cannot be repeated; this includes an empty string, a
pattern already followed by ‘##
’, or parentheses when part of a
KSH_GLOB
pattern (for example, ‘!(
foo)#
’ is
invalid and must be replaced by
‘*(!(
foo))
’).
##
(Requires EXTENDED_GLOB
to be set.)
Matches one or more occurrences of the pattern x.
This operator has high precedence; ‘12##
’ is equivalent to ‘1(2##)
’,
rather than ‘(12)##
’. No more than two active ‘#
’ characters may
appear together. (Note the potential clash with glob qualifiers in the
form ‘1(2##)
’ which should therefore be avoided.)
If the KSH_GLOB
option is set, the effects of parentheses can be
modified by a preceding ‘@
’, ‘*
’, ‘+
’, ‘?
’ or ‘!
’.
This character need not be unquoted to have special effects,
but the ‘(
’ must be.
@(
...)
Match the pattern in the parentheses. (Like ‘(
...)
’.)
*(
...)
Match any number of occurrences. (Like ‘(
...)#
’,
except that recursive directory searching is not supported.)
+(
...)
Match at least one occurrence. (Like ‘(
...)##
’,
except that recursive directory searching is not supported.)
?(
...)
Match zero or one occurrence. (Like ‘(|
...)
’.)
!(
...)
Match anything but the expression in parentheses.
(Like ‘(^(
...))
’.)
The precedence of the operators given above is (highest) ‘^
’, ‘/
’,
‘~
’, ‘|
’ (lowest); the
remaining operators are simply treated from left to right as part of a
string, with ‘#
’ and ‘##
’ applying to the shortest possible
preceding unit (i.e. a character, ‘?
’, ‘[
...]
’,
‘<
...>
’, or a parenthesised expression). As mentioned
above, a ‘/
’ used as a directory separator may not appear inside
parentheses, while a ‘|
’ must do so; in patterns used in other contexts
than filename generation (for example, in case
statements and tests
within ‘[[
...]]
’), a ‘/
’ is not special; and ‘/
’ is also
not special after a ‘~
’ appearing outside parentheses in a filename
pattern.
There are various flags which affect any text to their right up to the
end of the enclosing group or to the end of the pattern; they require
the EXTENDED_GLOB
option. All take the form
(#
X)
where X may have one of the following
forms:
i
Case insensitive: upper or lower case characters in the pattern match upper or lower case characters.
l
Lower case characters in the pattern match upper or lower case characters; upper case characters in the pattern still only match upper case characters.
I
Case sensitive: locally negates the effect of i
or l
from
that point on.
b
¶Activate backreferences for parenthesised groups in the pattern;
this does not work in filename generation. When a pattern with a set of
active parentheses is matched, the strings matched by the groups are
stored in the array $match
, the indices of the beginning of the matched
parentheses in the array $mbegin
, and the indices of the end in the array
$mend
, with the first element of each array corresponding to the first
parenthesised group, and so on. These arrays are not otherwise special to
the shell. The indices use the same convention as does parameter
substitution, so that elements of $mend
and $mbegin
may be used in
subscripts; the KSH_ARRAYS
option is respected. Sets of globbing flags
are not considered parenthesised groups; only the first nine active
parentheses can be referenced.
For example,
foo="a_string_with_a_message" if [[ $foo = (a|an)_(#b)(*) ]]; then print ${foo[$mbegin[1],$mend[1]]} fi
prints ‘string_with_a_message
’.
Note that the first set of parentheses is before the
(#b)
and does not create a backreference.
Backreferences work with all forms of pattern matching other than filename
generation, but note that when performing matches on an entire array, such
as ${
array#
pattern}
, or a global substitution, such
as ${
param//
pat/
repl}
, only the data for the
last match remains available. In the case of global replacements this may
still be useful. See the example for the m
flag below.
The numbering of backreferences strictly follows the order of the opening
parentheses from left to right in the pattern string, although sets of
parentheses may be nested. There are special rules for parentheses followed
by ‘#
’ or ‘##
’. Only the last match of the parenthesis is
remembered: for example, in ‘[[ abab = (#b)([ab])# ]]
’, only the final
‘b
’ is stored in match[1]
. Thus extra parentheses may be necessary
to match the complete segment: for example, use
‘X((ab|cd)#)Y
’ to match
a whole string of either ‘ab
’ or ‘cd
’ between ‘X
’ and ‘Y
’,
using the value of $match[1]
rather than $match[2]
.
If the match fails none of the parameters is altered, so in some cases it
may be necessary to initialise them beforehand. If some of the
backreferences fail to match — which happens if they are in an alternate
branch which fails to match, or if they are followed by #
and matched
zero times — then the matched string is set to the empty string, and the
start and end indices are set to -1.
Pattern matching with backreferences is slightly slower than without.
B
Deactivate backreferences, negating the effect of the b
flag from that
point on.
c
N,
MThe flag (#c
N,
M)
can be used anywhere
that the #
or ##
operators can be used except in the expressions
‘(*/)#
’ and ‘(*/)##
’ in filename generation, where ‘/
’
has special meaning; it cannot be combined with other globbing flags and
a bad pattern error occurs if it is misplaced. It is equivalent to the
form {
N,
M}
in regular expressions. The previous
character or group is required to match between N and M times,
inclusive. The form (#c
N)
requires exactly N
matches; (#c,
M)
is equivalent to specifying N
as 0; (#c
N,)
specifies that there is no maximum
limit on the number of matches.
m
¶Set references to the match data for the entire string matched; this is
similar to backreferencing and does not work in filename generation. The
flag must be in effect at the end of the pattern, i.e. not local to a
group. The parameters $MATCH
, $MBEGIN
and $MEND
will be set to
the string matched and to the indices of the beginning and end of the
string, respectively. This is most useful in parameter substitutions, as
otherwise the string matched is obvious.
For example,
arr=(veldt jynx grimps waqf zho buck) print ${arr//(#m)[aeiou]/${(U)MATCH}}
forces all the matches (i.e. all vowels) into uppercase, printing
‘vEldt jynx grImps wAqf zhO bUck
’.
Unlike backreferences, there is no speed penalty for using match references, other than the extra substitutions required for the replacement strings in cases such as the example shown.
M
Deactivate the m
flag, hence no references to match data will be
created.
a
numApproximate matching: num errors are allowed in the string matched by the pattern. The rules for this are described in the next subsection.
s
, e
Unlike the other flags, these have only a local effect, and each must
appear on its own: ‘(#s)
’ and ‘(#e)
’ are the only valid forms.
The ‘(#s)
’ flag succeeds only at the start of the test string, and the
‘(#e)
’ flag succeeds only at the end of the test string; they
correspond to ‘^
’ and ‘$
’ in standard regular expressions. They
are useful for matching path segments in patterns other than those in
filename generation (where path segments are in any case treated
separately). For example, ‘*((#s)|/)test((#e)|/)*
’ matches
a path segment ‘test
’ in any of the following strings: test
,
test/at/start
, at/end/test
, in/test/middle
.
Another use is in parameter substitution; for example
‘${array/(#s)A*Z(#e)}
’ will remove only elements of an
array which
match the complete pattern ‘A*Z
’. There are other ways of performing
many operations of this type, however the combination of the substitution
operations ‘/
’ and ‘//
’ with the ‘(#s)
’ and ‘(#e)
’ flags
provides a single simple and memorable method.
Note that assertions of the form ‘(^(#s))
’ also work, i.e. match
anywhere except at the start of the string, although this actually means
‘anything except a zero-length portion at the start of the string’; you
need to use ‘(""~(#s))
’ to match a zero-length portion of the string
not at the start.
q
A ‘q
’ and everything up to the closing parenthesis of the globbing
flags are ignored by the pattern matching code. This is intended to
support the use of glob qualifiers, see below. The result is that
the pattern ‘(#b)(*).c(#q.)
’ can be used both for globbing
and for
matching against a string. In the former case, the ‘(#q.)
’ will be
treated as a glob qualifier and the ‘(#b)
’ will not be useful, while in
the latter case the ‘(#b)
’ is useful for backreferences and the
‘(#q.)
’ will be ignored. Note that colon modifiers in the glob
qualifiers are also not applied in ordinary pattern matching.
u
Respect the current locale in determining the presence of multibyte
characters in a pattern, provided the shell was compiled with
MULTIBYTE_SUPPORT
. This overrides the MULTIBYTE
option; the default behaviour is taken from the option. Compare U
.
(Mnemonic: typically multibyte characters are from Unicode in the UTF-8
encoding, although any extension of ASCII supported by the system
library may be used.)
U
All characters are considered to be a single byte long. The opposite
of u
. This overrides the MULTIBYTE
option.
For example, the test string fooxx
can be matched by the pattern
(#i
)FOOXX
, but not by (#l
)FOOXX
,
(#i
)FOO
(#I
)XX
or
((#i
)FOOX
)X
. The string
(#ia2
)readme
specifies case-insensitive matching of
readme
with up to two errors.
When using the ksh syntax for grouping both KSH_GLOB
and
EXTENDED_GLOB
must be set and the left parenthesis should be
preceded by @
. Note also that the flags do not affect letters
inside [
...]
groups, in other words (#i
)[a-z]
still matches only lowercase letters. Finally, note that when
examining whole paths case-insensitively every directory must be
searched for all files which match, so that a pattern of the form
(#i
)/foo/bar/...
is potentially slow.
When matching approximately, the shell keeps a count of the errors found,
which cannot exceed the number specified in the
(#a
num)
flags. Four types of error are recognised:
Different characters, as in fooxbar
and fooybar
.
Transposition of characters, as in banana
and abnana
.
A character missing in the target string, as with the pattern road
and
target string rod
.
An extra character appearing in the target string, as with stove
and strove
.
Thus, the pattern (#a3
)abcd
matches dcba
, with the
errors occurring by using the first rule twice and the second once,
grouping the string as [d][cb][a]
and [a][bc][d]
.
Non-literal parts of the pattern must match exactly, including characters
in character ranges: hence (#a1
)???
matches strings of
length four, by applying rule 4 to an empty part of the pattern, but not
strings of length two, since all the ?
must match. Other characters
which must match exactly are initial dots in filenames (unless the
GLOB_DOTS
option is set), and all slashes in filenames, so that
a/bc
is two errors from ab/c
(the slash cannot be transposed with
another character). Similarly, errors are counted separately for
non-contiguous strings in the pattern, so that (ab|cd
)ef
is two errors from aebf
.
When using exclusion via the ~
operator, approximate matching is
treated entirely separately for the excluded part and must be activated
separately. Thus, (#a1
)README~READ_ME
matches
READ.ME
but not READ_ME
, as the trailing READ_ME
is matched
without approximation. However,
(#a1
)README~(#a1
)READ_ME
does not match any pattern of the form READ
?ME
as all
such forms are now excluded.
Apart from exclusions, there is only one overall error count; however, the
maximum errors allowed may be altered locally, and this can be delimited by
grouping. For example,
(#a1
)cat
((#a0
)dog
)fox
allows one error in total, which may not occur in the dog
section, and
the pattern
(#a1
)cat
(#a0
)dog
(#a1
)fox
is equivalent. Note that the point at which an error is first found is the
crucial one for establishing whether to use approximation; for example,
(#a1)abc(#a0)xyz
will not match abcdxyz
, because the
error occurs at the ‘x
’, where approximation is turned off.
Entire path segments may be matched approximately, so that
‘(#a1)/foo/d/is/available/at/the/bar
’ allows one error in any path
segment. This is much less efficient than without the (#a1)
, however,
since every directory in the path must be scanned for a possible
approximate match. It is best to place the (#a1)
after any path
segments which are known to be correct.
A pathname component of the form ‘(
foo/)#
’
matches a path consisting of zero or more directories
matching the pattern foo.
As a shorthand, ‘**/
’ is equivalent to ‘(*/)#
’; note that this
therefore matches files in the current directory as well as
subdirectories.
Thus:
ls -ld -- (*/)#bar
or
ls -ld -- **/bar
does a recursive directory search for files named ‘bar
’ (potentially
including the file ‘bar
’ in the current directory). This form does not
follow symbolic links; the alternative form ‘***/
’ does, but is
otherwise identical. Neither of these can be combined with other forms of
globbing within the same path segment; in that case, the ‘*
’
operators revert to their usual effect.
Even shorter forms are available when the option GLOB_STAR_SHORT
is
set. In that case if no /
immediately follows a **
or ***
they are treated as if both a /
plus a further *
are present.
Hence:
setopt GLOBSTARSHORT ls -ld -- **.c
is equivalent to
ls -ld -- **/*.c
Patterns used for filename generation may end in a list of qualifiers enclosed in parentheses. The qualifiers specify which filenames that otherwise match the given pattern will be inserted in the argument list.
If the option BARE_GLOB_QUAL
is set, then a trailing set of parentheses
containing no ‘|
’ or ‘(
’ characters (or ‘~
’ if it is special)
is taken as a set of
glob qualifiers. A glob subexpression that would normally be taken as glob
qualifiers, for example ‘(^x)
’, can be forced to be treated as part of
the glob pattern by doubling the parentheses, in this case producing
‘((^x))
’.
If the option EXTENDED_GLOB
is set, a different syntax for glob
qualifiers is available, namely ‘(#q
x)
’
where x is any of the same
glob qualifiers used in the other format. The qualifiers must still appear
at the end of the pattern. However, with this syntax multiple glob
qualifiers may be chained together. They are treated as a logical AND of
the individual sets of flags. Also, as the syntax is unambiguous, the
expression will be treated as glob qualifiers just as long any parentheses
contained within it are balanced; appearance of ‘|
’, ‘(
’ or
‘~
’ does not negate the effect. Note that qualifiers will be
recognised in this form even if a bare glob qualifier exists at the end of
the pattern, for example ‘*(#q*)(.)
’ will recognise executable regular
files if both options are set; however, mixed syntax should probably be
avoided for the sake of clarity. Note that within conditions using the
‘[[
’ form the presence of a parenthesised expression
(#q
...)
at the end of a string indicates that globbing
should be performed; the expression may include glob qualifiers, but
it is also valid if it is simply (#q)
. This does
not apply to the right hand side of pattern match operators as the
syntax already has special significance.
A qualifier may be any one of the following:
/
directories
F
‘full’ (i.e. non-empty) directories. Note that the
opposite sense (^F
)
expands to empty directories
and all non-directories. Use (/^F
)
for
empty directories.
.
plain files
@
symbolic links
=
sockets
p
named pipes (FIFOs)
*
executable plain files (0100 or 0010 or 0001)
%
device files (character or block special)
%b
block special files
%c
character special files
r
owner-readable files (0400)
w
owner-writable files (0200)
x
owner-executable files (0100)
A
group-readable files (0040)
I
group-writable files (0020)
E
group-executable files (0010)
R
world-readable files (0004)
W
world-writable files (0002)
X
world-executable files (0001)
s
setuid files (04000)
S
setgid files (02000)
t
files with the sticky bit (01000)
f
specfiles with access rights matching spec. This spec may be a
octal number optionally preceded by a ‘=
’, a ‘+
’, or a
‘-
’. If none of these characters is given, the behavior is the
same as for ‘=
’. The octal number describes the mode bits to be
expected, if combined with a ‘=
’, the value given must match the
file-modes exactly, with a ‘+
’, at least the bits in the
given number must be set in the file-modes, and with a ‘-
’, the
bits in the number must not be set. Giving a ‘?
’ instead of a
octal digit anywhere in the number ensures that the corresponding bits
in the file-modes are not checked, this is only useful in combination
with ‘=
’.
If the qualifier ‘f
’ is followed by any other character anything
up to the next matching character (‘[
’, ‘{
’, and ‘<
’ match
‘]
’, ‘}
’, and ‘>
’ respectively, any other character
matches itself) is taken as a list of comma-separated
sub-specs. Each sub-spec may be either an octal number as
described above or a list of any of the characters ‘u
’, ‘g
’,
‘o
’, and ‘a
’, followed by a ‘=
’, a ‘+
’, or a
‘-
’, followed by a list of any of the characters ‘r
’, ‘w
’,
‘x
’, ‘s
’, and ‘t
’, or an octal digit. The first list of
characters specify which access rights are to be checked. If a ‘u
’
is given, those for the owner of the file are used, if a ‘g
’ is
given, those of the group are checked, a ‘o
’ means to test those
of other users, and the ‘a
’ says to test all three groups. The
‘=
’, ‘+
’, and ‘-
’ again says how the modes are to be
checked and have the same meaning as described for the first form
above. The second list of characters finally says which access rights
are to be expected: ‘r
’ for read access, ‘w
’ for write access,
‘x
’ for the right to execute the file (or to search a directory),
‘s
’ for the setuid and setgid bits, and ‘t
’ for the sticky
bit.
Thus, ‘*(f70?)
’ gives the files for which the owner has read,
write, and execute permission, and for which other group members have
no rights, independent of the permissions for other users. The pattern
‘*(f-100)
’ gives all files for which the owner does not have
execute permission, and ‘*(f:gu+w,o-rx:)
’ gives the files for which
the owner and the other members of the group have at least write
permission, and for which other users don’t have read or execute
permission.
e
string+
cmdThe string will be executed as shell code. The filename will be included in the list if and only if the code returns a zero status (usually the status of the last command).
In the first form, the first character after the ‘e
’
will be used as a separator and anything up to the next matching separator
will be taken as the string; ‘[
’, ‘{
’, and ‘<
’ match
‘]
’, ‘}
’, and ‘>
’, respectively, while any other character
matches itself. Note that expansions must be quoted in the string
to prevent them from being expanded before globbing is done.
string is then executed as shell code. The string globqual
is appended to the array zsh_eval_context
the duration of
execution.
During the execution of string the filename currently being tested is
available in the parameter REPLY
; the parameter may be altered to
a string to be inserted into the list instead of the original
filename. In addition, the parameter reply
may be set to an array or a
string, which overrides the value of REPLY
. If set to an array, the
latter is inserted into the command line word by word.
For example, suppose a directory contains a single file ‘lonely
’. Then
the expression ‘*(e:'reply=(${REPLY}{1,2})':)
’ will cause the words
‘lonely1
’ and ‘lonely2
’ to be inserted into the command line. Note
the quoting of string.
The form +
cmd has the same effect, but no delimiters appear
around cmd. Instead, cmd is taken as the longest sequence of
characters following the +
that are alphanumeric or underscore.
Typically cmd will be the name of a shell function that contains the
appropriate test. For example,
nt() { [[ $REPLY -nt $NTREF ]] } NTREF=reffile ls -ld -- *(+nt)
lists all files in the directory that have been modified more recently than
reffile
.
d
devfiles on the device dev
l
[-
|+
]ctfiles having a link count less than ct (-
), greater than
ct (+
), or equal to ct
U
files owned by the effective user ID
G
files owned by the effective group ID
u
idfiles owned by user ID id if that is a number. Otherwise,
id specifies a user name: the
character after the ‘u
’ will be taken as a separator and the string
between it and the next matching separator will be taken as a user name.
The starting separators ‘[
’, ‘{
’, and ‘<
’
match the final separators ‘]
’, ‘}
’, and ‘>
’, respectively;
any other character matches itself. The selected files are those
owned by this user. For example, ‘u:foo:
’ or ‘u[foo]
’ selects
files owned by user ‘foo
’.
g
idlike u
id but with group IDs or names
a
[Mwhms
][-
|+
]nfiles accessed exactly n days ago. Files accessed within the last
n days are selected using a negative value for n (-
n).
Files accessed more than n days ago are selected by a positive n
value (+
n). Optional unit specifiers ‘M
’, ‘w
’,
‘h
’, ‘m
’ or ‘s
’ (e.g. ‘ah5
’) cause the check to be
performed with months (of 30 days), weeks, hours, minutes or seconds
instead of days, respectively. An explicit ‘d
’ for days is also
allowed.
Any fractional part of the difference between the access time and the
current part in the appropriate units is ignored in the comparison. For
instance, ‘echo *(ah-5)
’ would echo files accessed within the last
five hours, while ‘echo *(ah+5)
’ would echo files accessed at least
six hours ago, as times strictly between five and six hours are treated
as five hours.
m
[Mwhms
][-
|+
]nlike the file access qualifier, except that it uses the file modification time.
c
[Mwhms
][-
|+
]nlike the file access qualifier, except that it uses the file inode change time.
L
[+
|-
]nfiles less than n bytes (-
), more than n bytes (+
), or
exactly n bytes in length.
If this flag is directly followed by a size specifier ‘k
’ (‘K
’),
‘m
’ (‘M
’), or ‘p
’ (‘P
’) (e.g. ‘Lk-50
’) the check is
performed with kilobytes, megabytes, or blocks (of 512 bytes) instead.
(On some systems additional specifiers are available for gigabytes,
‘g
’ or ‘G
’, and terabytes, ‘t
’ or ‘T
’.) If a size specifier
is used a file is regarded as "exactly" the size if the file size rounded up
to the next unit is equal to the test size. Hence ‘*(Lm1)
’
matches files from 1 byte up to 1 Megabyte inclusive. Note also that
the set of files "less than" the test size only includes files that would
not match the equality test; hence ‘*(Lm-1)
’ only matches
files of zero size.
^
negates all qualifiers following it
-
toggles between making the qualifiers work on symbolic links (the
default) and the files they point to, if any; any symbolic link for
whose target the ‘stat
’ system call fails (whatever the cause of the
failure) is treated as a file in its own right
M
T
appends a trailing qualifier mark to the filenames, analogous to the
LIST_TYPES
option, for the current pattern (overrides M
)
N
D
n
Y
nenables short-circuit mode: the pattern will expand to at most n filenames. If more than n matches exist, only the first n matches in directory traversal order will be considered.
Implies oN
when no o
c qualifier is used.
o
cspecifies how the names of the files should be sorted. The following values of c sort in the following ways:
n
By name.
L
By the size (length) of the files.
l
By number of links.
a
By time of last access, youngest first.
m
By time of last modification, youngest first.
c
By time of last inode change, youngest first.
d
By directories: files in subdirectories appear before
those in the current directory at each level of the search — this is best
combined with other criteria, for example ‘odon
’ to sort on names for
files within the same directory.
N
No sorting is performed.
e
string+
cmdSort by shell code (see below).
Note that the modifiers ^
and -
are used,
so ‘*(^-oL)
’ gives a list of all files sorted by file size in descending
order, following any symbolic links. Unless oN
is used, multiple order
specifiers may occur to resolve ties.
The default sorting is n
(by name) unless the Y
glob qualifier is used,
in which case it is N
(unsorted).
oe
and o+
are special cases; they are each followed by shell code,
delimited as for the e
glob qualifier and the +
glob qualifier
respectively (see above). The code is executed for each matched file with
the parameter REPLY
set to the name of the file on entry and
globsort
appended to zsh_eval_context
. The code
should modify the parameter REPLY
in some fashion. On return, the
value of the parameter is used instead of the file name as the string on
which to sort. Unlike other sort operators, oe
and o+
may be
repeated, but note that the maximum number of sort operators of any kind
that may appear in any glob expression is 12.
O
clike ‘o
’, but sorts in descending order; i.e. ‘*(^o
c)
’ is the
same as ‘*(O
c)
’ and ‘*(^O
c)
’ is the same as ‘*(o
c)
’; ‘Od
’
puts files in the current directory before those in subdirectories at each
level of the search.
[
beg[,
end]]
specifies which of the matched filenames should be included in the
returned list. The syntax is the same as for array
subscripts. beg and the optional end may be mathematical
expressions. As in parameter subscripting they may be negative to make
them count from the last match backward. E.g.: ‘*(-OL[1,3])
’
gives a list of the names of the three largest files.
P
stringThe string will be prepended to each glob match as a separate
word. string is delimited in the same way as arguments to the
e
glob qualifier described above. The qualifier can be repeated;
the words are prepended separately so that the resulting command
line contains the words in the same order they were given in the
list of glob qualifiers.
A typical use for this is to prepend an option before all occurrences
of a file name; for example, the pattern ‘*(P:-f:)
’ produces the
command line arguments ‘-f
file1 -f
file2 ...’
If the modifier ^
is active, then string will be appended
instead of prepended. Prepending and appending is done independently
so both can be used on the same glob expression; for example by writing
‘*(P:foo:^P:bar:^P:baz:)
’ which produces the command line arguments
‘foo
baz
file1 bar
...’
More than one of these lists can be combined, separated by commas. The
whole list matches if at least one of the sublists matches (they are
‘or’ed, the qualifiers in the sublists are ‘and’ed). Some qualifiers,
however, affect all matches generated, independent of the sublist in
which they are given. These are the qualifiers ‘M
’, ‘T
’,
‘N
’, ‘D
’, ‘n
’, ‘o
’, ‘O
’ and the subscripts given
in brackets (‘[
...]
’).
If a ‘:
’ appears in a qualifier list, the remainder of the expression in
parenthesis is interpreted as a modifier (see Modifiers
in History Expansion). Each modifier must be introduced by a
separate ‘:
’. Note also that the result after modification does not
have to be an existing file. The name of any existing file can be followed
by a modifier of the form ‘(:
...)
’
even if no actual filename generation
is performed, although note that the presence of the parentheses
causes the entire expression to be subjected to any global pattern matching
options such as NULL_GLOB
. Thus:
ls -ld -- *(-/)
lists all directories and symbolic links that point to directories, and
ls -ld -- *(-@)
lists all broken symbolic links, and
ls -ld -- *(%W)
lists all world-writable device files in the current directory, and
ls -ld -- *(W,X)
lists all files in the current directory that are world-writable or world-executable, and
print -rC1 /tmp/foo*(u0^@:t)
outputs the basename of all root-owned files beginning with the string
‘foo
’ in /tmp
, ignoring symlinks, and
ls -ld -- *.*~(lex|parse).[ch](^D^l1)
lists all files having a link count of one whose names contain a dot
(but not those starting with a dot, since GLOB_DOTS
is explicitly
switched off) except for lex.c
, lex.h
, parse.c
and parse.h
.
print -rC1 b*.pro(#q:s/pro/shmo/)(#q.:s/builtin/shmiltin/)
demonstrates how colon modifiers and other qualifiers may be chained
together. The ordinary qualifier ‘.
’ is applied first, then the colon
modifiers in order from left to right. So if EXTENDED_GLOB
is set and
the base pattern matches the regular file builtin.pro
, the shell will
print ‘shmiltin.shmo
’.
A parameter has a name, a value, and a number of attributes.
A name may be any sequence of alphanumeric
characters and underscores, or the single characters
‘*
’, ‘@
’, ‘#
’, ‘?
’, ‘-
’, ‘$
’, or ‘!
’.
A parameter whose name begins with an alphanumeric or underscore is also
referred to as a variable.
The attributes of a parameter determine the type of its value, often referred to as the parameter type or variable type, and also control other processing that may be applied to the value when it is referenced. The value type may be a scalar (a string, an integer, or a floating point number), an array (indexed numerically), or an associative array (an unordered set of name-value pairs, indexed by name, also referred to as a hash).
Named scalar parameters may have the exported, -x
, attribute, to
copy them into the process environment, which is then passed from the
shell to any new processes that it starts. Exported parameters are called
environment variables. The shell also imports environment variables
at startup time and automatically marks the corresponding parameters as
exported. Some environment variables are not imported for reasons of
security or because they would interfere with the correct operation of
other shell features.
Parameters may also be special, that is, they have a predetermined meaning to the shell. Special parameters cannot have their type changed or their readonly attribute turned off, and if a special parameter is unset, then later recreated, the special properties will be retained.
To declare the type of a parameter, or to assign a string or numeric value
to a scalar parameter, use the typeset
builtin.
The value of a scalar parameter may also be assigned by writing:
name
=
value
In scalar assignment, value is expanded as a single string, in
which the elements of arrays are joined together; filename expansion is
not performed unless the option GLOB_ASSIGN
is set.
When the integer attribute, -i
, or a floating point attribute, -E
or -F
, is set for name, the value is subject to arithmetic
evaluation. Furthermore, by replacing ‘=
’ with ‘+=
’, a parameter
can be incremented or appended to. See Array Parameters and
Arithmetic Evaluation
for additional forms of assignment.
Note that assignment may implicitly change the attributes of a parameter.
For example, assigning a number to a variable in arithmetic evaluation may
change its type to integer or float, and with GLOB_ASSIGN
assigning a
pattern to a variable may change its type to an array.
To reference the value of a parameter, write ‘$
name’ or
‘${
name}
’. See
Parameter Expansion
for complete details. That section also explains the effect
of the difference between scalar and array assignment on parameter
expansion.
To assign an array value, write one of:
set -A
name value ...
name
=(
value ...)
name
=(
[
key]=
value ...)
If no parameter name exists, an ordinary array parameter is created. If the parameter name exists and is a scalar, it is replaced by a new array.
In the third form, key is an expression that will be evaluated in
arithmetic context (in its simplest form, an integer) that gives the
index of the element to be assigned with value. In this form any
elements not explicitly mentioned that come before the largest index to
which a value is assigned are assigned an empty string. The indices
may be in any order. Note that this syntax is strict: [
and ]=
must
not be quoted, and key may not consist of the unquoted string
]=
, but is otherwise treated as a simple string. The enhanced forms
of subscript expression that may be used when directly subscripting a
variable name, described in the section ‘Array Subscripts’ below, are not
available.
The syntaxes with and without the explicit key may be mixed. An implicit key is deduced by incrementing the index from the previously assigned element. Note that it is not treated as an error if latter assignments in this form overwrite earlier assignments.
For example, assuming the option KSH_ARRAYS
is not set, the following:
array=(one [3]=three four)
causes the array variable array
to contain four elements one
,
an empty string, three
and four
, in that order.
In the forms where only value is specified, full command line expansion is performed.
In the [
key]=
value form,
both key and value undergo all forms of expansion
allowed for single word shell expansions (this does not include filename
generation); these are as performed by the parameter expansion flag
(e)
as described in
Parameter Expansion.
Nested parentheses may surround value and are included as part of the
value, which is joined into a plain string; this differs from ksh which
allows the values themselves to be arrays. A future version of zsh may
support that. To cause the brackets to be interpreted as a character
class for filename generation, and therefore to treat the resulting list
of files as a set of values, quote the equal sign using any form of quoting.
Example:
name
=(
[a-z]'='*)
To append to an array without changing the existing values, use one of the following:
name
+=(
value ...)
name
+=(
[
key]=
value ...)
In the second form key may specify an existing index as well as an
index off the end of the old array; any existing value is overwritten by
value. Also, it is possible to use [
key]+=
value
to append to the existing value at that index.
Within the parentheses on the right hand side of either form of the assignment, newlines and semicolons are treated the same as white space, separating individual values. Any consecutive sequence of such characters has the same effect.
Ordinary array parameters may also be explicitly declared with:
typeset -a
name
Associative arrays must be declared before assignment, by using:
typeset -A
name
When name refers to an associative array, the list in an assignment is interpreted as alternating keys and values:
set -A
name key value ...
name
=(
key value ...)
name
=(
[
key]=
value ...)
Note that only one of the two syntaxes above may be used in any given assignment; the forms may not be mixed. This is unlike the case of numerically indexed arrays.
Every key must have a value in this case. Note that this assigns to the entire array, deleting any elements that do not appear in the list. The append syntax may also be used with an associative array:
name
+=(
key value ...)
name
+=(
[
key]=
value ...)
This adds a new key/value pair if the key is not already present, and
replaces the value for the existing key if it is. In the second
form it is also possible to use [
key]+=
value to
append to the existing value at that key. Expansion is performed
identically to the corresponding forms for normal arrays, as
described above.
To create an empty array (including associative arrays), use one of:
set -A
name
name
=()
Individual elements of an array may be selected using a subscript. A
subscript of the form ‘[
exp]
’ selects the single element
exp, where exp is an arithmetic expression which will be subject
to arithmetic expansion as if it were surrounded by
‘$((
...))
’. The elements are numbered
beginning with 1, unless the KSH_ARRAYS
option is set in which case
they are numbered from zero.
Subscripts may be used inside braces used to delimit a parameter name, thus
‘${foo[2]}
’ is equivalent to ‘$foo[2]
’. If the KSH_ARRAYS
option is set, the braced form is the only one that works, as bracketed
expressions otherwise are not treated as subscripts.
If the KSH_ARRAYS
option is not set, then by default accesses to
an array element with a subscript that evaluates to zero return an
empty string, while an attempt to write such an element is treated as
an error. For backward compatibility the KSH_ZERO_SUBSCRIPT
option can be set to cause subscript values 0 and 1 to be equivalent; see
the description of the option in Description of Options.
The same subscripting syntax is used for associative arrays, except that no arithmetic expansion is applied to exp. However, the parsing rules for arithmetic expressions still apply, which affects the way that certain special characters must be protected from interpretation. See Subscript Parsing below for details.
A subscript of the form ‘[*]
’ or ‘[@]
’ evaluates to all elements
of an array; there is no difference between the two except when they
appear within double quotes.
‘"$foo[*]"
’ evaluates to ‘"$foo[1] $foo[2]
..."
’, whereas
‘"$foo[@]"
’ evaluates to ‘"$foo[1]" "$foo[2]"
...’. For
associative arrays, ‘[*]
’ or ‘[@]
’ evaluate to all the values,
in no particular order. Note that this does not substitute
the keys; see the documentation for the ‘k
’ flag under
Parameter Expansion
for complete details.
When an array parameter is referenced as ‘$
name’ (with no
subscript) it evaluates to ‘$
name[*]
’, unless the KSH_ARRAYS
option is set in which case it evaluates to ‘${
name[0]}
’ (for
an associative array, this means the value of the key ‘0
’, which may
not exist even if there are values for other keys).
A subscript of the form ‘[
exp1,
exp2]
’
selects all elements in the range exp1 to exp2,
inclusive. (Associative arrays are unordered, and so do not support
ranges.) If one of the subscripts evaluates to a negative number,
say -
n, then the nth element from the end
of the array is used. Thus ‘$foo[-3]
’ is the third element
from the end of the array foo
, and
‘$foo[1,-1]
’ is the same as ‘$foo[*]
’.
Subscripting may also be performed on non-array values, in which
case the subscripts specify a substring to be extracted.
For example, if FOO
is set to ‘foobar
’, then
‘echo $FOO[2,5]
’ prints ‘ooba
’. Note that
some forms of subscripting described below perform pattern matching,
and in that case the substring extends from the start of the match
of the first subscript to the end of the match of the second
subscript. For example,
string="abcdefghijklm" print ${string[(r)d?,(r)h?]}
prints ‘defghi
’. This is an obvious generalisation of the
rule for single-character matches. For a single subscript,
only a single character is referenced (not the range of characters
covered by the match).
Note that in substring operations the second subscript is handled
differently by the r
and R
subscript flags: the former takes the
shortest match as the length and the latter the longest match. Hence
in the former case a *
at the end is redundant while in
the latter case it matches the whole remainder of the string. This
does not affect the result of the single subscript case as here the
length of the match is irrelevant.
A subscript may be used on the left side of an assignment like so:
name
[
exp]=
value
In this form of assignment the element or range specified by exp is replaced by the expression on the right side. An array (but not an associative array) may be created by assignment to a range or element. Arrays do not nest, so assigning a parenthesized list of values to an element or range changes the number of elements in the array, shifting the other elements to accommodate the new values. (This is not supported for associative arrays.)
This syntax also works as an argument to the typeset
command:
typeset
"
name[
exp]"=
value
The value may not be a parenthesized list in this case; only
single-element assignments may be made with typeset
. Note that quotes
are necessary in this case to prevent the brackets from being interpreted
as filename generation operators. The noglob
precommand modifier
could be used instead.
To delete an element of an ordinary array, assign ‘()
’ to
that element. To delete an element of an associative array, use the
unset
command:
unset
"
name[
exp]"
If the opening bracket, or the comma in a range, in any subscript
expression is directly followed by an opening parenthesis, the string up
to the matching closing one is considered to be a list of flags, as in
‘name[(
flags)
exp]
’.
The flags s
, n
and b
take an argument; the delimiter
is shown below as ‘:
’, but any character, or the matching pairs
‘(
...)
’, ‘{
...}
’, ‘[
...]
’, or
‘<
...>
’, may be used, but note that ‘<
...>
’ can only be
used if the subscript is inside a double quoted expression or a
parameter substitution enclosed in braces as otherwise the expression is
interpreted as a redirection.
The flags currently understood are:
w
If the parameter subscripted is a scalar then this flag makes
subscripting work on words instead of characters. The default word
separator is whitespace. When combined with the i
or I
flag,
the effect is to produce the index of the first character of the
first/last word which matches the given pattern; note that a failed
match in this case always yields 0.
s:
string:
This gives the string that separates words (for use with the
w
flag). The delimiter character :
is arbitrary; see above.
p
Recognize the same escape sequences as the print
builtin in
the string argument of a subsequent ‘s
’ flag.
f
If the parameter subscripted is a scalar then this flag makes
subscripting work on lines instead of characters, i.e. with elements
separated by newlines. This is a shorthand for ‘pws:\n:
’.
r
Reverse subscripting: if this flag is given, the exp is taken as a
pattern and the result is the first matching array element, substring or
word (if the parameter is an array, if it is a scalar, or if it is a
scalar and the ‘w
’ flag is given, respectively). The subscript used
is the number of the matching element, so that pairs of subscripts such as
‘$foo[(r)??,3]
’ and ‘$foo[(r)??,(r)f*]
’ are
possible if the parameter is not an associative array. If the
parameter is an associative array, only the value part of each pair is
compared to the pattern, and the result is that value.
If a search through an ordinary array failed, the search sets the
subscript to one past the end of the array, and hence
${array[(r)
pattern]}
will substitute the empty string. Thus the
success of a search can be tested by using the (i)
flag, for
example (assuming the option KSH_ARRAYS
is not in effect):
[[ ${array[(i)pattern]} -le ${#array} ]]
If KSH_ARRAYS
is in effect, the -le
should be replaced by -lt
.
R
Like ‘r
’, but gives the last match. For associative arrays, gives
all possible matches. May be used for assigning to ordinary array
elements, but not for assigning to associative arrays. On failure, for
normal arrays this has the effect of returning the element corresponding to
subscript 0; this is empty unless one of the options KSH_ARRAYS
or
KSH_ZERO_SUBSCRIPT
is in effect.
Note that in subscripts with both ‘r
’ and ‘R
’ pattern characters
are active even if they were substituted for a parameter (regardless of the
setting of GLOB_SUBST
which controls this feature in normal pattern
matching). The flag ‘e
’ can be added to inhibit pattern matching. As
this flag does not inhibit other forms of substitution, care is still
required; using a parameter to hold the key has the desired effect:
key2='original key' print ${array[(Re)$key2]}
i
Like ‘r
’, but gives the index of the match instead; this may not be
combined with a second argument. On the left side of an assignment,
behaves like ‘r
’. For associative arrays, the key part of each pair
is compared to the pattern, and the first matching key found is the
result. On failure substitutes the length of the array plus one, as
discussed under the description of ‘r
’, or the empty string for an
associative array.
Note: Although ‘i
’ may be applied to a scalar substitution to find
the offset of a substring, the results are likely to be misleading when
searching within substitutions that yield an empty string, or when
searching for the empty substring.
I
Like ‘i
’, but gives the index of the last match, or all possible
matching keys in an associative array. On failure substitutes 0, or
the empty string for an associative array. This flag is best when
testing for values or keys that do not exist.
Note: If the option KSH_ARRAYS
is in effect and no match is found, the
result is indistinguishable from the case when the first element of the array
matches.
k
If used in a subscript on an associative array, this flag causes the keys
to be interpreted as patterns, and returns the value for the first key
found where exp is matched by the key. Note this could be any
such key as no ordering of associative arrays is defined.
This flag does not work on the left side of an assignment to an associative
array element. If used on another type of parameter, this behaves like ‘r
’.
K
On an associative array this is like ‘k
’ but returns all values where
exp is matched by the keys. On other types of parameters this has
the same effect as ‘R
’.
n:
expr:
If combined with ‘r
’, ‘R
’, ‘i
’ or ‘I
’, makes them give
the nth or nth last match (if expr evaluates to
n). This flag is ignored when the array is associative.
The delimiter character :
is arbitrary; see above.
b:
expr:
If combined with ‘r
’, ‘R
’, ‘i
’ or ‘I
’, makes them begin
at the nth or nth last element, word, or character (if expr
evaluates to n). This flag is ignored when the array is associative.
The delimiter character :
is arbitrary; see above.
e
This flag causes any pattern matching that would be performed on the
subscript to use plain string matching instead. Hence
‘${array[(re)*]}
’ matches only the array element whose value is *
.
Note that other forms of substitution such as parameter substitution are
not inhibited.
This flag can also be used to force *
or @
to be interpreted as
a single key rather than as a reference to all values. It may be used
for either purpose on the left side of an assignment.
See Parameter Expansion Flags (Parameter Expansion) for additional ways to manipulate the results of array subscripting.
This discussion applies mainly to associative array key strings and to
patterns used for reverse subscripting (the ‘r
’, ‘R
’, ‘i
’,
etc. flags), but it may also affect parameter substitutions that appear
as part of an arithmetic expression in an ordinary subscript.
To avoid subscript parsing limitations in assignments to associative array elements, use the append syntax:
aa+=('key with "*strange*" characters' 'value string')
The basic rule to remember when writing a subscript expression is that all
text between the opening ‘[
’ and the closing ‘]
’ is interpreted
as if it were in double quotes (Quoting). However, unlike double quotes which normally cannot nest, subscript
expressions may appear inside double-quoted strings or inside other
subscript expressions (or both!), so the rules have two important
differences.
The first difference is that brackets (‘[
’ and ‘]
’) must appear as
balanced pairs in a subscript expression unless they are preceded by a
backslash (‘\
’). Therefore, within a subscript expression (and unlike
true double-quoting) the sequence ‘\[
’ becomes ‘[
’, and similarly
‘\]
’ becomes ‘]
’. This applies even in cases where a backslash is
not normally required; for example, the pattern ‘[^[]
’ (to match any
character other than an open bracket) should be written ‘[^\[]
’ in a
reverse-subscript pattern. However, note that ‘\[^\[\]
’ and even
‘\[^[]
’ mean the same thing, because backslashes are always
stripped when they appear before brackets!
The same rule applies to parentheses (‘(
’ and ‘)
’) and
braces (‘{
’ and ‘}
’): they must appear either in balanced pairs or
preceded by a backslash, and backslashes that protect parentheses or
braces are removed during parsing. This is because parameter expansions
may be surrounded by balanced braces, and subscript flags are introduced by
balanced parentheses.
The second difference is that a double-quote (‘"
’) may appear as part
of a subscript expression without being preceded by a backslash, and
therefore that the two characters ‘\"
’ remain as two characters in the
subscript (in true double-quoting, ‘\"
’ becomes ‘"
’). However,
because of the standard shell quoting rules, any double-quotes that appear
must occur in balanced pairs unless preceded by a backslash. This makes
it more difficult to write a subscript expression that contains an odd
number of double-quote characters, but the reason for this difference is
so that when a subscript expression appears inside true double-quotes, one
can still write ‘\"
’ (rather than ‘\\\"
’) for ‘"
’.
To use an odd number of double quotes as a key in an assignment, use the
typeset
builtin and an enclosing pair of double quotes; to refer to
the value of that key, again use double quotes:
typeset -A aa typeset "aa[one\"two\"three\"quotes]"=QQQ print "$aa[one\"two\"three\"quotes]"
It is important to note that the quoting rules do not change when a parameter expansion with a subscript is nested inside another subscript expression. That is, it is not necessary to use additional backslashes within the inner subscript expression; they are removed only once, from the innermost subscript outwards. Parameters are also expanded from the innermost subscript first, as each expansion is encountered left to right in the outer expression.
A further complication arises from a way in which subscript parsing is
not different from double quote parsing. As in true double-quoting,
the sequences ‘\*
’, and ‘\@
’ remain as two characters when they
appear in a subscript expression. To use a literal ‘*
’ or ‘@
’ as
an associative array key, the ‘e
’ flag must be used:
typeset -A aa aa[(e)*]=star print $aa[(e)*]
A last detail must be considered when reverse subscripting is performed.
Parameters appearing in the subscript expression are first expanded and
then the complete expression is interpreted as a pattern. This has two
effects: first, parameters behave as if GLOB_SUBST
were on (and it
cannot be turned off); second, backslashes are interpreted twice, once
when parsing the array subscript and again when parsing the pattern. In a
reverse subscript, it’s necessary to use four backslashes to cause a
single backslash to match literally in the pattern. For complex patterns,
it is often easiest to assign the desired pattern to a parameter and then
refer to that parameter in the subscript, because then the backslashes,
brackets, parentheses, etc., are seen only when the complete expression is
converted to a pattern. To match the value of a parameter literally in a
reverse subscript, rather than as a pattern,
use ‘${(q
)
name}
’ (Parameter Expansion) to quote the expanded value.
Note that the ‘k
’ and ‘K
’ flags are reverse subscripting for an
ordinary array, but are not reverse subscripting for an associative
array! (For an associative array, the keys in the array itself are
interpreted as patterns by those flags; the subscript is a plain string
in that case.)
One final note, not directly related to subscripting: the numeric names
of positional parameters (Positional Parameters) are parsed specially, so for example ‘$2foo
’ is equivalent to
‘${2}foo
’. Therefore, to use subscript syntax to extract a substring
from a positional parameter, the expansion must be surrounded by braces;
for example, ‘${2[3,5]}
’ evaluates to the third through fifth
characters of the second positional parameter, but ‘$2[3,5]
’ is the
entire second parameter concatenated with the filename generation pattern
‘[3,5]
’.
The positional parameters provide access to the command-line arguments
of a shell function, shell script, or the shell itself; see
Invocation, and also Functions.
The parameter n, where n is a number,
is the nth positional parameter.
The parameter ‘$0
’ is a special case, see
Parameters Set By The Shell.
The parameters *
, @
and argv
are
arrays containing all the positional parameters;
thus ‘$argv[
n]
’, etc., is equivalent to simply ‘$
n’.
Note that the options KSH_ARRAYS
or KSH_ZERO_SUBSCRIPT
apply
to these arrays as well, so with either of those options set,
‘${argv[0]}
’ is equivalent to ‘$1
’ and so on.
Positional parameters may be changed after the shell or function starts by
using the set
builtin, by assigning to the argv
array, or by direct
assignment of the form ‘n=
value’ where n is the number of
the positional parameter to be changed. This also creates (with empty
values) any of the positions from 1 to n that do not already have
values. Note that, because the positional parameters form an array, an
array assignment of the form ‘n=(
value ...)
’ is
allowed, and has the effect of shifting all the values at positions greater
than n by as many positions as necessary to accommodate the new values.
Shell function executions delimit scopes for shell parameters.
(Parameters are dynamically scoped.) The typeset
builtin, and its
alternative forms declare
, integer
, local
and readonly
(but not export
), can be used to declare a parameter as being local
to the innermost scope.
When a parameter is read or assigned to, the
innermost existing parameter of that name is used. (That is, the
local parameter hides any less-local parameter.) However, assigning
to a non-existent parameter, or declaring a new parameter with export
,
causes it to be created in the outermost scope.
Local parameters disappear when their scope ends.
unset
can be used to delete a parameter while it is still in scope;
any outer parameter of the same name remains hidden.
Special parameters may also be made local; they retain their special
attributes unless either the existing or the newly-created parameter
has the -h
(hide) attribute. This may have unexpected effects:
there is no default value, so if there is no assignment at the
point the variable is made local, it will be set to an empty value (or zero
in the case of integers).
The following:
typeset PATH=/new/directory:$PATH
is valid for temporarily allowing the shell or programmes called from it to
find the programs in /new/directory
inside a function.
Note that the restriction in older versions of zsh that local parameters were never exported has been removed.
In the parameter lists that follow, the mark ‘<S>’ indicates that the
parameter is special. ‘<Z>’ indicates that the parameter does not exist
when the shell initializes in sh
or ksh
emulation mode.
The parameters ‘!
’, ‘#
’, ‘*
’, ‘-
’, ‘?
’, ‘@
’,
‘$
’, ‘ARGC
’, ‘HISTCMD
’, ‘LINENO
’, ‘PPID
’,
‘status
’, ‘TTYIDLE
’, ‘zsh_eval_context
’,
‘ZSH_EVAL_CONTEXT
’, and ‘ZSH_SUBSHELL
’ are read-only and thus
cannot be restored by the user, so they are not output by
‘typeset -p
’. This also applies to many read-only parameters loaded
from modules.
The following parameters are automatically set by the shell:
!
<S> ¶The process ID of the last command started in the background with &
,
put into the background with the bg
builtin, or spawned with coproc
.
#
<S> ¶The number of positional parameters in decimal. Note that some confusion
may occur with the syntax $#
param which substitutes the length of
param. Use ${#}
to resolve ambiguities. In particular, the
sequence ‘$#-
...’ in an arithmetic expression is interpreted as
the length of the parameter -
, q.v.
ARGC
<S> <Z> ¶Same as #
.
$
<S> ¶The process ID of this shell, set when the shell initializes. Processes
forked from the shell without executing a new program, such as command
substitutions and commands grouped with (
...)
,
are subshells that duplicate the current shell, and thus substitute the
same value for $$
as their parent shell.
-
<S> ¶Flags supplied to the shell on invocation or by the set
or setopt
commands.
*
<S> ¶An array containing the positional parameters.
argv
<S> <Z> ¶Same as *
. Assigning to argv
changes the local positional
parameters, but argv
is not itself a local parameter.
Deleting argv
with unset
in any function deletes it everywhere,
although only the innermost positional parameter array is deleted (so
*
and @
in other scopes are not affected).
@
<S> ¶Same as argv[@]
, even when argv
is not set.
?
<S> ¶The exit status returned by the last command.
0
<S> ¶The name used to invoke the current shell, or as set by the -c
command
line option upon invocation. If the FUNCTION_ARGZERO
option is set,
$0
is set upon entry to a shell function to the name of the function,
and upon entry to a sourced script to the name of the script, and reset to
its previous value when the function or script returns.
status
<S> <Z> ¶Same as ?
.
pipestatus
<S> <Z> ¶An array containing the exit statuses returned by all commands in the last pipeline.
_
<S> ¶The last argument of the previous command. Also, this parameter is set in the environment of every command executed to the full pathname of the command.
CPUTYPE
¶The machine type (microprocessor class or machine model), as determined at run time.
EGID
<S> ¶The effective group ID of the shell process. If you have sufficient
privileges, you may change the effective group ID of the shell
process by assigning to this parameter. Also (assuming sufficient
privileges), you may start a single command with a different
effective group ID by ‘(EGID=
gid; command)
’
If this is made local, it is not implicitly set to 0, but may be explicitly set locally.
EUID
<S> ¶The effective user ID of the shell process. If you have sufficient
privileges, you may change the effective user ID of the shell process
by assigning to this parameter. Also (assuming sufficient privileges),
you may start a single command with a different
effective user ID by ‘(EUID=
uid; command)
’
If this is made local, it is not implicitly set to 0, but may be explicitly set locally.
ERRNO
<S> ¶The value of errno
(see errno(3))
as set by the most recently failed system call.
This value is system dependent and is intended for debugging
purposes. It is also useful with the zsh/system
module which
allows the number to be turned into a name or message.
To use this parameter, it must first be assigned a value (typically 0 (zero)). It is initially unset for scripting compatibility.
FUNCNEST
<S> ¶Integer. If greater than or equal to zero, the maximum nesting depth of shell functions. When it is exceeded, an error is raised at the point where a function is called. The default value is determined when the shell is configured, but is typically 500. Increasing the value increases the danger of a runaway function recursion causing the shell to crash. Setting a negative value turns off the check.
GID
<S> ¶The real group ID of the shell process. If you have sufficient privileges,
you may change the group ID of the shell process by assigning to this
parameter. Also (assuming sufficient privileges), you may start a single
command under a different
group ID by ‘(GID=
gid; command)
’
If this is made local, it is not implicitly set to 0, but may be explicitly set locally.
HISTCMD
¶The current history event number in an interactive shell, in other
words the event number for the command that caused $HISTCMD
to be read. If the current history event modifies the history,
HISTCMD
changes to the new maximum history event number.
HOST
¶The current hostname.
LINENO
<S> ¶The line number of the current line within the current script, sourced
file, or shell function being executed, whichever was started most
recently. Note that in the case of shell functions the line
number refers to the function as it appeared in the original definition,
not necessarily as displayed by the functions
builtin.
LOGNAME
¶If the corresponding variable is not set in the environment of the
shell, it is initialized to the login name corresponding to the
current login session. This parameter is exported by default but
this can be disabled using the typeset
builtin. The value
is set to the string returned by the getlogin(3) system call
if that is available.
MACHTYPE
¶The machine type (microprocessor class or machine model), as determined at compile time.
OLDPWD
¶The previous working directory. This is set when the shell initializes and whenever the directory changes.
OPTARG
<S> ¶The value of the last option argument processed by the getopts
command.
OPTIND
<S> ¶The index of the last option argument processed by the getopts
command.
OSTYPE
¶The operating system, as determined at compile time.
PPID
<S> ¶The process ID of the parent of the shell, set when the shell initializes.
As with $$
, the value does not change in subshells created as a
duplicate of the current shell.
PWD
¶The present working directory. This is set when the shell initializes and whenever the directory changes.
RANDOM
<S> ¶A pseudo-random integer from 0 to 32767, newly generated each time
this parameter is referenced. The random number generator
can be seeded by assigning a numeric value to RANDOM
.
The values of RANDOM
form an intentionally-repeatable pseudo-random
sequence; subshells that reference RANDOM
will result
in identical pseudo-random values unless the value of RANDOM
is
referenced or seeded in the parent shell in between subshell invocations.
SECONDS
<S> ¶The number of seconds since shell invocation. If this parameter is assigned a value, then the value returned upon reference will be the value that was assigned plus the number of seconds since the assignment.
Unlike other special parameters, the type of the SECONDS
parameter can
be changed using the typeset
command. The type may be changed only
to one of the floating point types or back to integer. For example,
‘typeset -F SECONDS
’
causes the value to be reported as a floating point number. The
value is available to microsecond accuracy, although the shell may
show more or fewer digits depending on the use of typeset
. See
the documentation for the builtin typeset
in
Shell Builtin Commands for more details.
SHLVL
<S> ¶Incremented by one each time a new shell is started.
signals
¶An array containing the names of the signals. Note that with
the standard zsh numbering of array indices, where the first element
has index 1, the signals are offset by 1 from the signal number
used by the operating system. For example, on typical Unix-like systems
HUP
is signal number 1, but is referred to as $signals[2]
. This
is because of EXIT
at position 1 in the array, which is used
internally by zsh but is not known to the operating system.
TRY_BLOCK_ERROR
<S> ¶In an always
block, indicates whether the preceding list of code
caused an error. The value is 1 to indicate an error, 0 otherwise.
It may be reset, clearing the error condition. See
Complex Commands
TRY_BLOCK_INTERRUPT
<S> ¶This variable works in a similar way to TRY_BLOCK_ERROR
, but
represents the status of an interrupt from the signal SIGINT, which
typically comes from the keyboard when the user types ^C
. If set to
0, any such interrupt will be reset; otherwise, the interrupt is
propagated after the always
block.
Note that it is possible that an interrupt arrives during the execution
of the always
block; this interrupt is also propagated.
TTY
¶The name of the tty associated with the shell, if any.
TTYIDLE
<S> ¶The idle time of the tty associated with the shell in seconds or -1 if there is no such tty.
UID
<S> ¶The real user ID of the shell process. If you have sufficient privileges,
you may change the user ID of the shell by assigning to this parameter.
Also (assuming sufficient privileges), you may start a single command
under a different
user ID by ‘(UID=
uid; command)
’
If this is made local, it is not implicitly set to 0, but may be explicitly set locally.
USERNAME
<S> ¶The username corresponding to the real user ID of the shell process. If you
have sufficient privileges, you may change the username (and also the
user ID and group ID) of the shell by assigning to this parameter.
Also (assuming sufficient privileges), you may start a single command
under a different username (and user ID and group ID)
by ‘(USERNAME=
username; command)
’
VENDOR
¶The vendor, as determined at compile time.
zsh_eval_context
<S> <Z> (ZSH_EVAL_CONTEXT
<S>) ¶An array (colon-separated list) indicating the context of shell code that is being run. Each time a piece of shell code that is stored within the shell is executed a string is temporarily appended to the array to indicate the type of operation that is being performed. Read in order the array gives an indication of the stack of operations being performed with the most immediate context last.
Note that the variable does not give information on syntactic context such
as pipelines or subshells. Use $ZSH_SUBSHELL
to detect subshells.
The context is one of the following:
cmdarg
Code specified by the -c
option to the command line that invoked
the shell.
cmdsubst
Command substitution using the `
...`
or
$(
...)
construct.
equalsubst
File substitution using the =(
...)
construct.
eval
Code executed by the eval
builtin.
evalautofunc
Code executed with the KSH_AUTOLOAD
mechanism in order to define
an autoloaded function.
fc
Code from the shell history executed by the -e
option to the fc
builtin.
file
Lines of code being read directly from a file, for example by
the source
builtin.
filecode
Lines of code being read from a .zwc
file instead of directly
from the source file.
globqual
Code executed by the e
or +
glob qualifier.
globsort
Code executed to order files by the o
glob qualifier.
insubst
File substitution using the <(
...)
construct.
loadautofunc
Code read directly from a file to define an autoloaded function.
outsubst
File substitution using the >(
...)
construct.
sched
Code executed by the sched
builtin.
shfunc
A shell function.
stty
Code passed to stty
by the STTY
environment variable.
Normally this is passed directly to the system’s stty
command,
so this value is unlikely to be seen in practice.
style
Code executed as part of a style retrieved by the zstyle
builtin
from the zsh/zutil
module.
toplevel
The highest execution level of a script or interactive shell.
trap
Code executed as a trap defined by the trap
builtin. Traps
defined as functions have the context shfunc
. As traps are
asynchronous they may have a different hierarchy from other
code.
zpty
Code executed by the zpty
builtin from the zsh/zpty
module.
zregexparse-guard
Code executed as a guard by the zregexparse
command from the
zsh/zutil
module.
zregexparse-action
Code executed as an action by the zregexparse
command from the
zsh/zutil
module.
ZSH_ARGZERO
¶If zsh was invoked to run a script, this is the name of the script.
Otherwise, it is the name used to invoke the current shell. This is
the same as the value of $0
when the POSIX_ARGZERO
option is
set, but is always available.
ZSH_EXECUTION_STRING
¶If the shell was started with the option -c
, this contains
the argument passed to the option. Otherwise it is not set.
ZSH_NAME
¶Expands to the basename of the command used to invoke this instance of zsh.
ZSH_PATCHLEVEL
¶The output of ‘git describe --tags --long
’ for the zsh repository
used to build the shell. This is most useful in order to keep
track of versions of the shell during development between releases;
hence most users should not use it and should instead rely on
$ZSH_VERSION
.
zsh_scheduled_events
See The zsh/sched Module.
ZSH_SCRIPT
¶If zsh was invoked to run a script, this is the name of the script, otherwise it is unset.
ZSH_SUBSHELL
¶Readonly integer. Initially zero, incremented each time the shell forks
to create a subshell for executing code. Hence ‘(print $ZSH_SUBSHELL)
’
and ‘print $(print $ZSH_SUBSHELL)
’ output 1, while
‘( (print $ZSH_SUBSHELL) )
’ outputs 2.
ZSH_VERSION
¶The version number of the release of zsh.
The following parameters are used by the shell. Again, ‘<S>’ indicates
that the parameter is special and ‘<Z>’ indicates that the parameter does
not exist when the shell initializes in sh
or ksh
emulation mode.
In cases where there are two parameters with an upper- and lowercase
form of the same name, such as path
and PATH
, the lowercase form
is an array and the uppercase form is a scalar with the elements of the
array joined together by colons. These are similar to tied parameters
created via ‘typeset -T
’. The normal use for the colon-separated
form is for exporting to the environment, while the array form is easier
to manipulate within the shell. Note that unsetting either of the pair
will unset the other; they retain their special properties when
recreated, and recreating one of the pair will recreate the other.
ARGV0
¶If exported, its value is used as the argv[0]
of external commands.
Usually used in constructs like ‘ARGV0=emacs nethack
’.
BAUD
¶The rate in bits per second at which data reaches the terminal. The line editor will use this value in order to compensate for a slow terminal by delaying updates to the display until necessary. If the parameter is unset or the value is zero the compensation mechanism is turned off. The parameter is not set by default.
This parameter may be profitably set in some circumstances, e.g. for slow modems dialing into a communications server, or on a slow wide area network. It should be set to the baud rate of the slowest part of the link for best performance.
cdpath
<S> <Z> (CDPATH
<S>) ¶An array (colon-separated list)
of directories specifying the search path for the cd
command.
COLUMNS
<S> ¶The number of columns for this terminal session. Used for printing select lists and for the line editor.
CORRECT_IGNORE
¶If set, is treated as a pattern during spelling correction. Any
potential correction that matches the pattern is ignored. For example,
if the value is ‘_*
’ then completion functions (which, by
convention, have names beginning with ‘_
’) will never be offered
as spelling corrections. The pattern does not apply to the correction
of file names, as applied by the CORRECT_ALL
option (so with the
example just given files beginning with ‘_
’ in the current
directory would still be completed).
CORRECT_IGNORE_FILE
¶If set, is treated as a pattern during spelling correction of file names.
Any file name that matches the pattern is never offered as a correction.
For example, if the value is ‘.*
’ then dot file names will never be
offered as spelling corrections. This is useful with the
CORRECT_ALL
option.
DIRSTACKSIZE
¶The maximum size of the directory stack, by default there is no limit. If the
stack gets larger than this, it will be truncated automatically.
This is useful with the AUTO_PUSHD
option.
ENV
¶If the ENV
environment variable is set when zsh is invoked as sh
or ksh
, $ENV
is sourced after the profile scripts. The value of
ENV
is subjected to parameter expansion, command substitution, and
arithmetic expansion before being interpreted as a pathname. Note that
ENV
is not used unless the shell is interactive and zsh is
emulating sh or ksh.
FCEDIT
¶The default editor for the fc
builtin. If FCEDIT
is not set,
the parameter EDITOR
is used; if that is not set either, a builtin
default, usually vi
, is used.
fignore
<S> <Z> (FIGNORE
<S>) ¶An array (colon separated list) containing the suffixes of files to be ignored during filename completion. However, if completion only generates files with suffixes in this list, then these files are completed anyway.
fpath
<S> <Z> (FPATH
<S>) ¶An array (colon separated list)
of directories specifying the search path for
function definitions. This path is searched when a function
with the -u
attribute is referenced. If an executable
file is found, then it is read and executed in the current environment.
histchars
<S> ¶Three characters used by the shell’s history and lexical analysis
mechanism. The first character signals the start of a history
expansion (default ‘!
’). The second character signals the
start of a quick history substitution (default ‘^
’). The third
character is the comment character (default ‘#
’).
The characters must be in the ASCII character set; any attempt to set
histchars
to characters with a locale-dependent meaning will be
rejected with an error message.
HISTCHARS
<S> <Z> ¶Same as histchars
. (Deprecated.)
HISTFILE
¶The file to save the history in when an interactive shell exits. If unset, the history is not saved.
HISTORY_IGNORE
¶If set, is treated as a pattern at the time history files are written.
Any potential history entry that matches the pattern is skipped. For
example, if the value is ‘fc *
’ then commands that invoke the
interactive history editor are never written to the history file.
Note that HISTORY_IGNORE
defines a single pattern: to
specify alternatives use the
‘(
first|
second|
...)
’ syntax.
Compare the HIST_NO_STORE
option or the zshaddhistory
hook,
either of which would prevent such commands from being added to the
interactive history at all. If you wish to use HISTORY_IGNORE
to
stop history being added in the first place, you can define the
following hook:
zshaddhistory() { emulate -L zsh ## uncomment if HISTORY_IGNORE ## should use EXTENDED_GLOB syntax # setopt extendedglob [[ $1 != ${~HISTORY_IGNORE} ]] }
HISTSIZE
<S> ¶The maximum number of events stored in the internal history list.
If you use the HIST_EXPIRE_DUPS_FIRST
option, setting this value
larger than the SAVEHIST
size will give you the difference as a
cushion for saving duplicated history events.
If this is made local, it is not implicitly set to 0, but may be explicitly set locally.
HOME
<S> ¶The default argument for the cd
command. This is not set automatically
by the shell in sh
, ksh
or csh
emulation, but it is typically
present in the environment anyway, and if it becomes set it has its usual
special behaviour.
IFS
<S> ¶Internal field separators (by default space, tab, newline and NUL), that
are used to separate words which result from
command or parameter expansion and words read by
the read
builtin. Any characters from the set space, tab and
newline that appear in the IFS are called IFS white space.
One or more IFS white space characters or one non-IFS white space
character together with any adjacent IFS white space character delimit
a field. If an IFS white space character appears twice consecutively
in the IFS, this character is treated as if it were not an IFS white
space character.
If the parameter is unset, the default is used. Note this has a different effect from setting the parameter to an empty string.
KEYBOARD_HACK
¶This variable defines a character to be removed from the end of the
command line before interpreting it (interactive shells only). It is
intended to fix the problem with keys placed annoyingly close to return
and replaces the SUNKEYBOARDHACK
option which did this for
backquotes only. Should the chosen character be one of singlequote,
doublequote or backquote, there must also be an odd number of them
on the command line for the last one to be removed.
For backward compatibility, if the SUNKEYBOARDHACK
option is
explicitly set, the value of KEYBOARD_HACK
reverts to backquote.
If the option is explicitly unset, this variable is set to empty.
KEYTIMEOUT
¶The time the shell waits, in hundredths of seconds, for another key to be pressed when reading bound multi-character sequences.
LANG
<S> ¶This variable determines the locale category for any category not
specifically selected via a variable starting with ‘LC_
’.
LC_ALL
<S> ¶This variable overrides the value of the ‘LANG
’ variable and the value
of any of the other variables starting with ‘LC_
’.
LC_COLLATE
<S> ¶This variable determines the locale category for character collation information within ranges in glob brackets and for sorting.
LC_CTYPE
<S> ¶This variable determines the locale category for character handling
functions. If the MULTIBYTE
option is in effect this variable or
LANG
should contain a value that reflects the character set in
use, even if it is a single-byte character set, unless only the
7-bit subset (ASCII) is used. For example, if the character set
is ISO-8859-1, a suitable value might be en_US.iso88591
(certain
Linux distributions) or en_US.ISO8859-1
(MacOS).
LC_MESSAGES
<S> ¶This variable determines the language in which messages should be written. Note that zsh does not use message catalogs.
LC_NUMERIC
<S> ¶This variable affects the decimal point character and thousands separator character for the formatted input/output functions and string conversion functions. Note that zsh ignores this setting when parsing floating point mathematical expressions.
LC_TIME
<S> ¶This variable determines the locale category for date and time formatting in prompt escape sequences.
LINES
<S> ¶The number of lines for this terminal session. Used for printing select lists and for the line editor.
LISTMAX
¶In the line editor, the number of matches to list without asking first. If the value is negative, the list will be shown if it spans at most as many lines as given by the absolute value. If set to zero, the shell asks only if the top of the listing would scroll off the screen.
MAIL
¶If this parameter is set and mailpath
is not set,
the shell looks for mail in the specified file.
MAILCHECK
¶The interval in seconds between checks for new mail.
mailpath
<S> <Z> (MAILPATH
<S>) ¶An array (colon-separated list) of filenames to check for
new mail. Each filename can be followed by a ‘?
’ and a
message that will be printed. The message will undergo
parameter expansion, command substitution and arithmetic
expansion with the variable $_
defined as the name
of the file that has changed. The default message is
‘You have new mail
’. If an element is a directory
instead of a file the shell will recursively check every
file in every subdirectory of the element.
manpath
<S> <Z> (MANPATH
<S> <Z>) ¶An array (colon-separated list)
whose value is not used by the shell. The manpath
array can be useful, however, since setting it also sets
MANPATH
, and vice versa.
match
mbegin
mend
Arrays set by the shell when the b
globbing flag is used in pattern
matches. See the subsection Globbing flags in
Filename Generation.
MATCH
MBEGIN
MEND
Set by the shell when the m
globbing flag is used in pattern
matches. See the subsection Globbing flags in
Filename Generation.
module_path
<S> <Z> (MODULE_PATH
<S>) ¶An array (colon-separated list)
of directories that zmodload
searches for dynamically loadable modules.
This is initialized to a standard pathname,
usually ‘/usr/local/lib/zsh/$ZSH_VERSION
’.
(The ‘/usr/local/lib
’ part varies from installation to installation.)
For security reasons, any value set in the environment when the shell
is started will be ignored.
These parameters only exist if the installation supports dynamic module loading.
NULLCMD
<S> ¶The command name to assume if a redirection is specified
with no command. Defaults to cat
. For sh/ksh
behavior, change this to :
. For csh-like
behavior, unset this parameter; the shell will print an
error message if null commands are entered.
path
<S> <Z> (PATH
<S>) ¶An array (colon-separated list) of directories to search for commands. When this parameter is set, each directory is scanned and all files found are put in a hash table.
POSTEDIT
<S> ¶This string is output whenever the line editor exits. It usually contains termcap strings to reset the terminal.
PROMPT
<S> <Z> ¶PROMPT2
<S> <Z>PROMPT3
<S> <Z>PROMPT4
<S> <Z>Same as PS1
, PS2
, PS3
and PS4
,
respectively.
prompt
<S> <Z> ¶Same as PS1
.
PROMPT_EOL_MARK
¶When the PROMPT_CR
and PROMPT_SP
options are set, the
PROMPT_EOL_MARK
parameter can be used to customize how the end of
partial lines are shown. This parameter undergoes prompt expansion, with
the PROMPT_PERCENT
option set. If not set, the default behavior is
equivalent to the value ‘%B%S%#%s%b
’.
PS1
<S> ¶The primary prompt string, printed before a command is read.
It undergoes a special form of expansion
before being displayed; see
Prompt Expansion. The default is ‘%m%#
’.
PS2
<S> ¶The secondary prompt, printed when the shell needs more information
to complete a command.
It is expanded in the same way as PS1
.
The default is ‘%_>
’, which displays any shell constructs or quotation
marks which are currently being processed.
PS3
<S> ¶Selection prompt used within a select
loop.
It is expanded in the same way as PS1
.
The default is ‘?#
’.
PS4
<S> ¶The execution trace prompt. Default is ‘+%N:%i>
’, which displays
the name of the current shell structure and the line number within it.
In sh or ksh emulation, the default is ‘+
’.
psvar
<S> <Z> (PSVAR
<S>) ¶An array (colon-separated list) whose elements can be used in
PROMPT
strings. Setting psvar
also sets PSVAR
, and
vice versa.
READNULLCMD
<S> ¶The command name to assume if a single input redirection
is specified with no command. Defaults to more
.
REPORTMEMORY
¶If nonnegative, commands whose maximum resident set size (roughly
speaking, main memory usage) in kilobytes is greater than this
value have timing statistics reported. The format used to output
statistics is the value of the TIMEFMT
parameter, which is the same
as for the REPORTTIME
variable and the time
builtin; note that
by default this does not output memory usage. Appending
" max RSS %M"
to the value of TIMEFMT
causes it to output the
value that triggered the report. If REPORTTIME
is also in use,
at most a single report is printed for both triggers. This feature
requires the getrusage()
system call, commonly supported by
modern Unix-like systems.
REPORTTIME
¶If nonnegative, commands whose combined user and system execution times
(measured in seconds) are greater than this value have timing
statistics printed for them. Output is suppressed for commands
executed within the line editor, including completion; commands
explicitly marked with the time
keyword still cause the summary
to be printed in this case.
REPLY
¶This parameter is reserved by convention to pass string values between
shell scripts and shell builtins in situations where a function call or
redirection are impossible or undesirable. The read
builtin and the
select
complex command may set REPLY
, and filename generation both
sets and examines its value when evaluating certain expressions. Some
modules also employ REPLY
for similar purposes.
reply
¶As REPLY
, but for array values rather than strings.
RPROMPT
<S> ¶RPS1
<S>This prompt is displayed on the right-hand side of the screen
when the primary prompt is being displayed on the left.
This does not work if the SINGLE_LINE_ZLE
option is set.
It is expanded in the same way as PS1
.
RPROMPT2
<S> ¶RPS2
<S>This prompt is displayed on the right-hand side of the screen
when the secondary prompt is being displayed on the left.
This does not work if the SINGLE_LINE_ZLE
option is set.
It is expanded in the same way as PS2
.
SAVEHIST
¶The maximum number of history events to save in the history file.
If this is made local, it is not implicitly set to 0, but may be explicitly set locally.
SPROMPT
<S> ¶The prompt used for spelling correction. The sequence
‘%R
’ expands to the string which presumably needs spelling
correction, and ‘%r
’ expands to the proposed correction.
All other prompt escapes are also allowed.
The actions available at the prompt are [nyae]
:
n
(‘no’) (default)Discard the correction and run the command.
y
(‘yes’)Make the correction and run the command.
a
(‘abort’)Discard the entire command line without running it.
e
(‘edit’)Resume editing the command line.
STTY
¶If this parameter is set in a command’s environment, the shell runs the
stty
command with the value of this parameter as arguments in order to
set up the terminal before executing the command. The modes apply only to the
command, and are reset when it finishes or is suspended. If the command is
suspended and continued later with the fg
or wait
builtins it will
see the modes specified by STTY
, as if it were not suspended. This
(intentionally) does not apply if the command is continued via ‘kill
-CONT
’. STTY
is ignored if the command is run in the background, or
if it is in the environment of the shell but not explicitly assigned to in
the input line. This avoids running stty at every external command by
accidentally exporting it. Also note that STTY
should not be used for
window size specifications; these will not be local to the command.
If the parameter is set and empty, all of the above applies except
that stty
is not run. This can be useful as a way to freeze the tty
around a single command, blocking its changes to tty settings,
similar to the ttyctl
builtin.
TERM
<S> ¶The type of terminal in use. This is used when looking up termcap
sequences. An assignment to TERM
causes zsh to re-initialize the
terminal, even if the value does not change (e.g., ‘TERM=$TERM
’). It
is necessary to make such an assignment upon any change to the terminal
definition database or terminal type in order for the new settings to
take effect.
TERMINFO
<S> ¶A reference to your terminfo database, used by the ‘terminfo’ library when the
system has it; see terminfo(5).
If set, this causes the shell to reinitialise the terminal, making the
workaround ‘TERM=$TERM
’ unnecessary.
TERMINFO_DIRS
<S> ¶A colon-seprarated list of terminfo databases, used by the ‘terminfo’ library
when the system has it; see terminfo(5). This variable is only
used by certain terminal libraries, in particular ncurses; see
terminfo(5) to check support on your system. If set, this
causes the shell to reinitialise the terminal, making the workaround
‘TERM=$TERM
’ unnecessary. Note that unlike other colon-separated
arrays this is not tied to a zsh array.
TIMEFMT
¶The format of process time reports with the time
keyword.
The default is ‘%J %U user %S system %P cpu %*E total
’.
Recognizes the following escape sequences, although not all
may be available on all systems, and some that are available
may not be useful:
%%
A ‘%
’.
%U
CPU seconds spent in user mode.
%S
CPU seconds spent in kernel mode.
%E
Elapsed time in seconds.
%P
The CPU percentage, computed as
100*(%U
+%S
)/%E
.
%W
Number of times the process was swapped.
%X
The average amount in (shared) text space used in kilobytes.
%D
The average amount in (unshared) data/stack space used in kilobytes.
%K
The total space used (%X
+%D
) in kilobytes.
%M
The maximum memory the process had in use at any time in kilobytes.
%F
The number of major page faults (page needed to be brought from disk).
%R
The number of minor page faults.
%I
The number of input operations.
%O
The number of output operations.
%r
The number of socket messages received.
%s
The number of socket messages sent.
%k
The number of signals received.
%w
Number of voluntary context switches (waits).
%c
Number of involuntary context switches.
%J
The name of this job.
A star may be inserted between the percent sign and flags printing time
(e.g., ‘%*E
’); this causes the time to be printed in
‘hh:
mm:
ss.
ttt’
format (hours and minutes are only printed if they are not zero).
Alternatively, ‘m
’ or ‘u
’ may be used (e.g., ‘%mE
’) to produce
time output in milliseconds or microseconds, respectively.
TMOUT
¶If this parameter is nonzero, the shell will receive an ALRM
signal if a command is not entered within the specified number of
seconds after issuing a prompt. If there is a trap on SIGALRM
, it
will be executed and a new alarm is scheduled using the value of the
TMOUT
parameter after executing the trap. If no trap is set, and
the idle time of the terminal is not less than the value of the
TMOUT
parameter, zsh terminates. Otherwise a new alarm is
scheduled to TMOUT
seconds after the last keypress.
TMPPREFIX
¶A pathname prefix which the shell will use for all temporary files.
Note that this should include an initial part for the file name as
well as any directory names. The default is ‘/tmp/zsh
’.
TMPSUFFIX
¶A filename suffix which the shell will use for temporary files created
by process substitutions (e.g., ‘=(list)
’).
Note that the value should include a leading dot ‘.
’ if intended
to be interpreted as a file extension. The default is not to append
any suffix, thus this parameter should be assigned only when needed
and then unset again.
WORDCHARS
<S> ¶A list of non-alphanumeric characters considered part of a word by the line editor.
ZBEEP
¶If set, this gives a string of characters, which can use all the same codes
as the bindkey
command as described in
The zsh/zle Module, that will be output to the terminal
instead of beeping. This may have a visible instead of an audible effect;
for example, the string ‘\e[?5h\e[?5l
’ on a vt100 or xterm will have
the effect of flashing reverse video on and off (if you usually use reverse
video, you should use the string ‘\e[?5l\e[?5h
’ instead). This takes
precedence over the NOBEEP
option.
ZDOTDIR
¶The directory to search for shell startup files (.zshrc, etc),
if not $HOME
.
zle_bracketed_paste
¶Many terminal emulators have a feature that allows applications to identify when text is pasted into the terminal rather than being typed normally. For ZLE, this means that special characters such as tabs and newlines can be inserted instead of invoking editor commands. Furthermore, pasted text forms a single undo event and if the region is active, pasted text will replace the region.
This two-element array contains the terminal escape sequences for enabling and disabling the feature. These escape sequences are used to enable bracketed paste when ZLE is active and disable it at other times. Unsetting the parameter has the effect of ensuring that bracketed paste remains disabled.
zle_highlight
¶An array describing contexts in which ZLE should highlight the input text. See Character Highlighting.
ZLE_LINE_ABORTED
¶This parameter is set by the line editor when an error occurs. It
contains the line that was being edited at the point of the error.
‘print -zr -- $ZLE_LINE_ABORTED
’ can be used to recover the line.
Only the most recent line of this kind is remembered.
ZLE_REMOVE_SUFFIX_CHARS
¶ZLE_SPACE_SUFFIX_CHARS
These parameters are used by the line editor. In certain circumstances suffixes (typically space or slash) added by the completion system will be removed automatically, either because the next editing command was not an insertable character, or because the character was marked as requiring the suffix to be removed.
These variables can contain the sets of characters that will cause the
suffix to be removed. If ZLE_REMOVE_SUFFIX_CHARS
is set, those
characters will cause the suffix to be removed; if
ZLE_SPACE_SUFFIX_CHARS
is set, those characters will cause the
suffix to be removed and replaced by a space.
If ZLE_REMOVE_SUFFIX_CHARS
is not set, the default behaviour is
equivalent to:
ZLE_REMOVE_SUFFIX_CHARS=$' \t\n;&|'
If ZLE_REMOVE_SUFFIX_CHARS
is set but is empty, no characters have this
behaviour. ZLE_SPACE_SUFFIX_CHARS
takes precedence, so that the
following:
ZLE_SPACE_SUFFIX_CHARS=$'&|'
causes the characters ‘&
’ and ‘|
’ to remove the suffix but to
replace it with a space.
To illustrate the difference, suppose that the option AUTO_REMOVE_SLASH
is in effect and the directory DIR
has just been completed, with an
appended /
, following which the user types ‘&
’. The default result
is ‘DIR&
’. With ZLE_REMOVE_SUFFIX_CHARS
set but without including
‘&
’ the result is ‘DIR/&
’. With ZLE_SPACE_SUFFIX_CHARS
set to
include ‘&
’ the result is ‘DIR &
’.
Note that certain completions may provide their own suffix removal or replacement behaviour which overrides the values described here. See the completion system documentation in Completion System.
ZLE_RPROMPT_INDENT
<S> ¶If set, used to give the indentation between the right hand side of
the right prompt in the line editor as given by RPS1
or RPROMPT
and the right hand side of the screen. If not set, the value 1 is used.
Typically this will be used to set the value to 0 so that the prompt appears flush with the right hand side of the screen. This is not the default as many terminals do not handle this correctly, in particular when the prompt appears at the extreme bottom right of the screen. Recent virtual terminals are more likely to handle this case correctly. Some experimentation is necessary.
Options are primarily referred to by name.
These names are case insensitive and underscores are ignored.
For example, ‘allexport
’ is equivalent to ‘A__lleXP_ort
’.
The sense of an option name may be inverted by preceding it with
‘no
’, so ‘setopt No_Beep
’ is equivalent to ‘unsetopt beep
’.
This inversion can only be done once, so ‘nonobeep
’ is not
a synonym for ‘beep
’. Similarly, ‘tify
’ is not a synonym for
‘nonotify
’ (the inversion of ‘notify
’).
Some options also have one or more single letter names.
There are two sets of single letter options: one used by default,
and another used to emulate sh/ksh (used when the
SH_OPTION_LETTERS
option is set).
The single letter options can be used on the shell command line,
or with the set
, setopt
and unsetopt
builtins, as normal Unix options preceded by ‘-
’.
The sense of the single letter options may be inverted by using
‘+
’ instead of ‘-
’.
Some of the single letter option names refer to an option being off,
in which case the inversion of that name refers to the option being on.
For example, ‘+n
’ is the short name of ‘exec
’, and
‘-n
’ is the short name of its inversion, ‘noexec
’.
In strings of single letter options supplied to the shell at startup,
trailing whitespace will be ignored; for example the string ‘-f
’
will be treated just as ‘-f
’, but the string ‘-f i
’ is an error.
This is because many systems which implement the ‘#!
’ mechanism for
calling scripts do not strip trailing whitespace.
It is possible for options to be set within a function scope. See the
description of the option LOCAL_OPTIONS
below.
In the following list, options set by default in all emulations are marked
<D>; those set by default only in csh, ksh, sh, or zsh emulations are marked
<C>, <K>, <S>, <Z> as appropriate. When listing options (by ‘setopt
’,
‘unsetopt
’, ‘set -o
’ or ‘set +o
’), those turned on by default
appear in the list prefixed with ‘no
’. Hence (unless
KSH_OPTION_PRINT
is set), ‘setopt
’ shows all options whose settings
are changed from the default.
AUTO_CD
(-J
) ¶If a command is issued that can’t be executed as a normal command,
and the command is the name of a directory, perform the cd
command to that directory.
This option is only applicable if the option SHIN_STDIN
is set,
i.e. if commands are being read from standard input. The option
is designed for interactive use; it is recommended that cd
be used explicitly in scripts to avoid ambiguity.
AUTO_PUSHD
(-N
) ¶Make cd
push the old directory onto the directory stack.
CDABLE_VARS
(-T
) ¶If the argument to a cd
command (or an implied cd
with the
AUTO_CD
option set) is not a directory, and does not begin with a
slash, try to expand the expression as if it were preceded by a ‘~
’ (see
Filename Expansion).
CD_SILENT
¶Never print the working directory after a cd
(whether explicit or
implied with the AUTO_CD
option set). cd
normally prints the
working directory when the argument given to it was -
, a stack entry, or
the name of a directory found under CDPATH
. Note that this is distinct
from pushd
’s stack-printing behaviour, which is controlled by
PUSHD_SILENT
. This option overrides the printing-related effects of
POSIX_CD
.
CHASE_DOTS
¶When changing to a directory containing a path segment ‘..
’ which would
otherwise be treated as canceling the previous segment in the path (in
other words, ‘foo/..
’ would be removed from the path, or if ‘..
’ is
the first part of the path, the last part of the current working directory
would be removed), instead resolve the path to the physical directory.
This option is overridden by CHASE_LINKS
.
For example, suppose /foo/bar
is a link to the directory /alt/rod
.
Without this option set, ‘cd /foo/bar/..
’ changes to /foo
; with it
set, it changes to /alt
. The same applies if the current directory
is /foo/bar
and ‘cd ..
’ is used. Note that all other symbolic
links in the path will also be resolved.
CHASE_LINKS
(-w
) ¶Resolve symbolic links to their true values when changing directory.
This also has the effect of CHASE_DOTS
, i.e. a ‘..
’ path segment
will be treated as referring to the physical parent, even if the preceding
path segment is a symbolic link.
POSIX_CD
<K> <S> ¶Modifies the behaviour of cd
, chdir
and pushd
commands
to make them more compatible with the POSIX standard. The behaviour with
the option unset is described in the documentation for the cd
builtin in
Shell Builtin Commands.
If the option is set, the shell does not test for directories beneath
the local directory (‘.
’) until after all directories in cdpath
have been tested, and the cd
and chdir
commands do not recognise
arguments of the form ‘{+
|-
}n’ as directory stack entries.
Also, if the option is set, the conditions under which the shell
prints the new directory after changing to it are modified. It is
no longer restricted to interactive shells (although printing of
the directory stack with pushd
is still limited to interactive
shells); and any use of a component of CDPATH
, including a ‘.
’ but
excluding an empty component that is otherwise treated as ‘.
’, causes
the directory to be printed.
PUSHD_IGNORE_DUPS
¶Don’t push multiple copies of the same directory onto the directory stack.
PUSHD_MINUS
¶Exchanges the meanings of ‘+
’ and ‘-
’
when used with a number to specify a directory in the stack.
PUSHD_SILENT
(-E
) ¶Do not print the directory stack after pushd
or popd
.
PUSHD_TO_HOME
(-D
) ¶Have pushd
with no arguments act like ‘pushd $HOME
’.
ALWAYS_LAST_PROMPT
<D> ¶If unset, key functions that list completions try to return to the last prompt if given a numeric argument. If set these functions try to return to the last prompt if given no numeric argument.
ALWAYS_TO_END
¶If a completion is performed with the cursor within a word, and a full completion is inserted, the cursor is moved to the end of the word. That is, the cursor is moved to the end of the word if either a single match is inserted or menu completion is performed.
AUTO_LIST
(-9
) <D> ¶Automatically list choices on an ambiguous completion.
AUTO_MENU
<D> ¶Automatically use menu completion after the second consecutive request for
completion, for example by pressing the tab key repeatedly. This option
is overridden by MENU_COMPLETE
.
AUTO_NAME_DIRS
¶Any parameter that is set to the absolute name of a directory
immediately becomes a name for that directory, that will be used
by the ‘%~
’
and related prompt sequences, and will be available when completion
is performed on a word starting with ‘~
’.
(Otherwise, the parameter must be used in the form ‘~
param’ first.)
AUTO_PARAM_KEYS
<D> ¶If a parameter name was completed and a following character
(normally a space) automatically
inserted, and the next character typed is one
of those that have to come directly after the name (like ‘}
’, ‘:
’,
etc.), the automatically added character is deleted, so that the character
typed comes immediately after the parameter name.
Completion in a brace expansion is affected similarly: the added character
is a ‘,
’, which will be removed if ‘}
’ is typed next.
AUTO_PARAM_SLASH
<D> ¶If a parameter is completed whose content is the name of a directory, then add a trailing slash instead of a space.
AUTO_REMOVE_SLASH
<D> ¶When the last character resulting from a completion is a slash and the next character typed is a word delimiter, a slash, or a character that ends a command (such as a semicolon or an ampersand), remove the slash.
BASH_AUTO_LIST
¶On an ambiguous completion, automatically list choices when the
completion function is called twice in succession. This takes
precedence over AUTO_LIST
. The setting of LIST_AMBIGUOUS
is
respected. If AUTO_MENU
is set, the menu behaviour will then start
with the third press. Note that this will not work with
MENU_COMPLETE
, since repeated completion calls immediately cycle
through the list in that case.
COMPLETE_ALIASES
¶Prevents aliases on the command line from being internally substituted before completion is attempted. The effect is to make the alias a distinct command for completion purposes.
COMPLETE_IN_WORD
¶If unset, the cursor is set to the end of the word if completion is started. Otherwise it stays there and completion is done from both ends.
GLOB_COMPLETE
¶When the current word has a glob pattern, do not insert all the words
resulting from the expansion but generate matches as for completion and
cycle through them like MENU_COMPLETE
. The matches are generated as if
a ‘*
’ was added to the end of the word, or inserted at the cursor when
COMPLETE_IN_WORD
is set. This actually uses pattern matching, not
globbing, so it works not only for files but for any completion, such as
options, user names, etc.
Note that when the pattern matcher is used, matching control (for example,
case-insensitive or anchored matching) cannot be used. This limitation
only applies when the current word contains a pattern; simply turning
on the GLOB_COMPLETE
option does not have this effect.
HASH_LIST_ALL
<D> ¶Whenever a command completion or spelling correction is attempted, make sure the entire command path is hashed first. This makes the first completion slower but avoids false reports of spelling errors.
LIST_AMBIGUOUS
<D> ¶This option works when AUTO_LIST
or BASH_AUTO_LIST
is also
set. If there is an unambiguous prefix to insert on the command line,
that is done without a completion list being displayed; in other
words, auto-listing behaviour only takes place when nothing would be
inserted. In the case of BASH_AUTO_LIST
, this means that the list
will be delayed to the third call of the function.
LIST_BEEP
<D> ¶Beep on an ambiguous completion. More accurately, this forces the
completion widgets to return status 1 on an ambiguous completion, which
causes the shell to beep if the option BEEP
is also set; this may
be modified if completion is called from a user-defined widget.
LIST_PACKED
¶Try to make the completion list smaller (occupying less lines) by printing the matches in columns with different widths.
LIST_ROWS_FIRST
¶Lay out the matches in completion lists sorted horizontally, that is, the second match is to the right of the first one, not under it as usual.
LIST_TYPES
(-X
) <D> ¶When listing files that are possible completions, show the type of each file with a trailing identifying mark.
MENU_COMPLETE
(-Y
) ¶On an ambiguous completion, instead of listing possibilities or beeping,
insert the first match immediately. Then when completion is requested
again, remove the first match and insert the second match, etc.
When there are no more matches, go back to the first one again.
reverse-menu-complete
may be used to loop through the list
in the other direction. This option overrides AUTO_MENU
.
REC_EXACT
(-S
) ¶If the string on the command line exactly matches one of the possible completions, it is accepted, even if there is another completion (i.e. that string with something else added) that also matches.
BAD_PATTERN
(+2
) <C> <Z> ¶If a pattern for filename generation is badly formed, print an error message. (If this option is unset, the pattern will be left unchanged.)
BARE_GLOB_QUAL
<Z> ¶In a glob pattern, treat a trailing set of parentheses as a qualifier
list, if it contains no ‘|
’, ‘(
’ or (if special) ‘~
’
characters. See Filename Generation.
BRACE_CCL
¶Expand expressions in braces which would not otherwise undergo brace expansion to a lexically ordered list of all the characters. See Brace Expansion.
CASE_GLOB
<D> ¶Make globbing (filename generation) sensitive to case. Note that other
uses of patterns are always sensitive to case. If the option is unset,
the presence of any character which is special to filename generation
will cause case-insensitive matching. For example, cvs(/)
can match the directory CVS
owing to the presence of the globbing flag
(unless the option BARE_GLOB_QUAL
is unset).
CASE_MATCH
<D> ¶Make regular expressions using the zsh/regex
module (including
matches with =~
) sensitive to case.
CASE_PATHS
¶If CASE_PATHS
is not set (the default), CASE_GLOB
affects the
interpretation of every path component, whenever a special
character appears in any component. When CASE_PATHS
is set,
file path components that do not contain special filename
generation characters are always sensitive to case, thus restricting
NO_CASE_GLOB
to components that contain globbing characters.
Note that if the filesystem itself is not sensitive to case, then
CASE_PATHS
has no effect.
CSH_NULL_GLOB
<C> ¶If a pattern for filename generation has no matches,
delete the pattern from the argument list;
do not report an error unless all the patterns
in a command have no matches.
Overrides NOMATCH
.
EQUALS
<Z> ¶Perform =
filename expansion.
(See Filename Expansion.)
EXTENDED_GLOB
¶Treat the ‘#
’, ‘~
’ and ‘^
’ characters as part of patterns
for filename generation, etc. (An initial unquoted ‘~
’
always produces named directory expansion.)
FORCE_FLOAT
¶Constants in arithmetic evaluation will be treated as floating point even without the use of a decimal point; the values of integer variables will be converted to floating point when used in arithmetic expressions. Integers in any base will be converted.
GLOB
(+F
, ksh: +f
) <D> ¶Perform filename generation (globbing). (See Filename Generation.)
GLOB_ASSIGN
<C> ¶If this option is set, filename generation (globbing) is
performed on the right hand side of scalar parameter assignments of
the form ‘name=
pattern (e.g. ‘foo=*
’).
If the result has more than one word the parameter will become an array
with those words as arguments. This option is provided for backwards
compatibility only: globbing is always performed on the right hand side
of array assignments of the form ‘name=(
value)
’
(e.g. ‘foo=(*)
’) and this form is recommended for clarity;
with this option set, it is not possible to predict whether the result
will be an array or a scalar.
GLOB_DOTS
(-4
) ¶Do not require a leading ‘.
’ in a filename to be matched explicitly.
GLOB_STAR_SHORT
¶When this option is set and the default zsh-style globbing is in
effect, the pattern ‘**/*
’ can be abbreviated to ‘**
’ and the
pattern ‘***/*
’ can be abbreviated to ***
. Hence ‘**.c
’
finds a file ending in .c
in any subdirectory, and ‘***.c
’ does
the same while also following symbolic links. A /
immediately
after the ‘**
’ or ‘***
’ forces the pattern to be treated as the
unabbreviated form.
GLOB_SUBST
<C> <K> <S> ¶Treat any characters resulting from parameter expansion as being eligible for filename expansion and filename generation, and any characters resulting from command substitution as being eligible for filename generation. Braces (and commas in between) do not become eligible for expansion.
HIST_SUBST_PATTERN
¶Substitutions using the :s
and :&
history modifiers are performed
with pattern matching instead of string matching. This occurs wherever
history modifiers are valid, including glob qualifiers and parameters.
See
Modifiers.
IGNORE_BRACES
(-I
) <S> ¶Do not perform brace expansion. For historical reasons this
also includes the effect of the IGNORE_CLOSE_BRACES
option.
IGNORE_CLOSE_BRACES
¶When neither this option nor IGNORE_BRACES
is set, a sole
close brace character ‘}
’ is syntactically significant at any
point on a command line. This has the effect that no semicolon
or newline is necessary before the brace terminating a function
or current shell construct. When either option is set, a closing brace
is syntactically significant only in command position. Unlike
IGNORE_BRACES
, this option does not disable brace expansion.
For example, with both options unset a function may be defined in the following fashion:
args() { echo $# }
while if either option is set, this does not work and something equivalent to the following is required:
args() { echo $#; }
KSH_GLOB
<K> ¶In pattern matching, the interpretation of parentheses is affected by
a preceding ‘@
’, ‘*
’, ‘+
’, ‘?
’ or ‘!
’.
See Filename Generation.
MAGIC_EQUAL_SUBST
¶All unquoted arguments of the form ‘anything=
expression’
appearing after the command name have filename expansion (that is,
where expression has a leading ‘~
’ or ‘=
’) performed on
expression as if it were a parameter assignment. The argument is
not otherwise treated specially; it is passed to the command as a single
argument, and not used as an actual parameter assignment. For example, in
echo foo=~/bar:~/rod
, both occurrences of ~
would be replaced.
Note that this happens anyway with typeset
and similar statements.
This option respects the setting of the KSH_TYPESET
option. In other
words, if both options are in effect, arguments looking like
assignments will not undergo word splitting.
MARK_DIRS
(-8
, ksh: -X
) ¶Append a trailing ‘/
’ to all directory
names resulting from filename generation (globbing).
MULTIBYTE
<D> ¶Respect multibyte characters when found in strings. When this option is set, strings are examined using the system library to determine how many bytes form a character, depending on the current locale. This affects the way characters are counted in pattern matching, parameter values and various delimiters.
The option is on by default if the shell was compiled with
MULTIBYTE_SUPPORT
; otherwise it is off by default and has no effect
if turned on.
If the option is off a single byte is always treated as a single character. This setting is designed purely for examining strings known to contain raw bytes or other values that may not be characters in the current locale. It is not necessary to unset the option merely because the character set for the current locale does not contain multibyte characters.
The option does not affect the shell’s editor, which always uses the locale to determine multibyte characters. This is because the character set displayed by the terminal emulator is independent of shell settings.
NOMATCH
(+3
) <C> <Z> ¶If a pattern for filename generation has no matches,
print an error, instead of
leaving it unchanged in the argument list.
This also applies to file expansion
of an initial ‘~
’ or ‘=
’.
NULL_GLOB
(-G
) ¶If a pattern for filename generation has no matches,
delete the pattern from the argument list instead
of reporting an error. Overrides NOMATCH
.
NUMERIC_GLOB_SORT
¶If numeric filenames are matched by a filename generation pattern, sort the filenames numerically rather than lexicographically.
RC_EXPAND_PARAM
(-P
) ¶Array expansions of the form
‘foo${
xx}
bar’, where the parameter
xx is set to (
a b c)
, are substituted with
‘fooabar foobbar foocbar’ instead of the default
‘fooa b cbar’. Note that an empty array will therefore cause
all arguments to be removed.
REMATCH_PCRE
¶If set, regular expression matching with the =~
operator will use
Perl-Compatible Regular Expressions from the PCRE library.
(The zsh/pcre
module must be available.)
If not set, regular expressions will use the extended regexp syntax
provided by the system libraries.
SH_GLOB
<K> <S> ¶Disables the special meaning of ‘(
’, ‘|
’, ‘)
’
and ’<
’ for globbing the result of parameter and command substitutions,
and in some other places where
the shell accepts patterns. If SH_GLOB
is set but KSH_GLOB
is
not, the shell allows the interpretation of
subshell expressions enclosed in parentheses in some cases where there
is no space before the opening parenthesis, e.g. !(true)
is interpreted as if there were a space after the !
. This option is
set by default if zsh is invoked as sh
or ksh
.
UNSET
(+u
, ksh: +u
) <K> <S> <Z> ¶Treat unset parameters as if they were empty when substituting, and as if they were zero when reading their values in arithmetic expansion and arithmetic commands. Otherwise they are treated as an error.
WARN_CREATE_GLOBAL
¶Print a warning message when a global parameter is created in a function
by an assignment or in math context.
This often indicates that a parameter has not been
declared local when it should have been. Parameters explicitly declared
global from within a function using typeset -g
do not cause a warning.
Note that there is no warning when a local parameter is assigned to in
a nested function, which may also indicate an error.
WARN_NESTED_VAR
¶Print a warning message when an existing parameter from an
enclosing function scope, or global, is set in a function
by an assignment or in math context. Assignment to shell
special parameters does not cause a warning. This is the companion
to WARN_CREATE_GLOBAL
as in this case the warning is only
printed when a parameter is not created. Where possible,
use of typeset -g
to set the parameter suppresses the error,
but note that this needs to be used every time the parameter is set.
To restrict the effect of this option to a single function scope,
use ‘functions -W
’.
For example, the following code produces a warning for the assignment
inside the function nested
as that overrides the value within
toplevel
toplevel() { local foo="in fn" nested } nested() { foo="in nested" } setopt warn_nested_var toplevel
APPEND_HISTORY
<D> ¶If this is set, zsh sessions will append their history list to
the history file, rather than replace it. Thus, multiple parallel
zsh sessions will all have the new entries from their history lists
added to the history file, in the order that they exit.
The file will still be periodically re-written to trim it when the
number of lines grows 20% beyond the value specified by
$SAVEHIST
(see also the HIST_SAVE_BY_COPY
option).
BANG_HIST
(+K
) <C> <Z> ¶Perform textual history expansion, csh-style,
treating the character ‘!
’ specially.
EXTENDED_HISTORY
<C> ¶Save each command’s beginning timestamp (in seconds since the epoch) and the duration (in seconds) to the history file. The format of this prefixed data is:
‘:
<beginning time>:
<elapsed seconds>;
<command>’.
HIST_ALLOW_CLOBBER
¶Add ‘|
’ to output redirections in the history. This allows history
references to clobber files even when CLOBBER
is unset.
HIST_BEEP
<D> ¶Beep in ZLE when a widget attempts to access a history entry which isn’t there.
HIST_EXPIRE_DUPS_FIRST
¶If the internal history needs to be trimmed to add the current command line,
setting this option will cause the oldest history event that has a duplicate
to be lost before losing a unique event from the list.
You should be sure to set the value of HISTSIZE
to a larger number
than SAVEHIST
in order to give you some room for the duplicated
events, otherwise this option will behave just like
HIST_IGNORE_ALL_DUPS
once the history fills up with unique events.
HIST_FCNTL_LOCK
¶When writing out the history file, by default zsh uses ad-hoc file locking
to avoid known problems with locking on some operating systems. With this
option locking is done by means of the system’s fcntl
call, where
this method is available. On recent operating systems this may
provide better performance, in particular avoiding history corruption when
files are stored on NFS.
HIST_FIND_NO_DUPS
¶When searching for history entries in the line editor, do not display duplicates of a line previously found, even if the duplicates are not contiguous.
HIST_IGNORE_ALL_DUPS
¶If a new command line being added to the history list duplicates an older one, the older command is removed from the list (even if it is not the previous event).
HIST_IGNORE_DUPS
(-h
) ¶Do not enter command lines into the history list if they are duplicates of the previous event.
HIST_IGNORE_SPACE
(-g
) ¶Remove command lines from the history list when the first character on the line is a space, or when one of the expanded aliases contains a leading space. Only normal aliases (not global or suffix aliases) have this behaviour. Note that the command lingers in the internal history until the next command is entered before it vanishes, allowing you to briefly reuse or edit the line. If you want to make it vanish right away without entering another command, type a space and press return.
HIST_LEX_WORDS
¶By default, shell history that is read in from files is split into words on all white space. This means that arguments with quoted whitespace are not correctly handled, with the consequence that references to words in history lines that have been read from a file may be inaccurate. When this option is set, words read in from a history file are divided up in a similar fashion to normal shell command line handling. Although this produces more accurately delimited words, if the size of the history file is large this can be slow. Trial and error is necessary to decide.
HIST_NO_FUNCTIONS
¶Remove function definitions from the history list. Note that the function lingers in the internal history until the next command is entered before it vanishes, allowing you to briefly reuse or edit the definition.
HIST_NO_STORE
¶Remove the history
(fc -l
) command from the history list
when invoked.
Note that the command lingers in the internal history until the next
command is entered before it vanishes, allowing you to briefly reuse
or edit the line.
HIST_REDUCE_BLANKS
¶Remove superfluous blanks from each command line being added to the history list.
HIST_SAVE_BY_COPY
<D> ¶When the history file is re-written, we normally write out a copy of
the file named $HISTFILE.new
and then rename it over the old one.
However, if this option is unset, we instead truncate the old
history file and write out the new version in-place. If one of the
history-appending options is enabled, this option only has an effect
when the enlarged history file needs to be re-written to trim it
down to size. Disable this only if you have special needs, as doing
so makes it possible to lose history entries if zsh gets interrupted
during the save.
When writing out a copy of the history file, zsh preserves the old file’s permissions and group information, but will refuse to write out a new file if it would change the history file’s owner.
HIST_SAVE_NO_DUPS
¶When writing out the history file, older commands that duplicate newer ones are omitted.
HIST_VERIFY
¶Whenever the user enters a line with history expansion, don’t execute the line directly; instead, perform history expansion and reload the line into the editing buffer.
INC_APPEND_HISTORY
¶This option works like APPEND_HISTORY
except that new history lines
are added to the $HISTFILE
incrementally (as soon as they are
entered), rather than waiting until the shell exits.
The file will still be periodically re-written to trim it when the
number of lines grows 20% beyond the value specified by
$SAVEHIST
(see also the HIST_SAVE_BY_COPY
option).
INC_APPEND_HISTORY_TIME
¶This option is a variant of INC_APPEND_HISTORY
in which, where
possible, the history entry is written out to the file after the
command is finished, so that the time taken by the command is recorded
correctly in the history file in EXTENDED_HISTORY
format. This
means that the history entry will not be available immediately from
other instances of the shell that are using the same history file.
This option is only useful if INC_APPEND_HISTORY
and
SHARE_HISTORY
are turned off. The three options should be
considered mutually exclusive.
SHARE_HISTORY
<K> ¶This option both imports new commands from the history file, and also
causes your typed commands to be appended to the history file (the
latter is like specifying INC_APPEND_HISTORY
, which should be turned
off if this option is in effect). The history lines are also output
with timestamps ala EXTENDED_HISTORY
(which makes it easier to find
the spot where we left off reading the file after it gets re-written).
By default, history movement commands visit the imported lines as well as the local lines, but you can toggle this on and off with the set-local-history zle binding. It is also possible to create a zle widget that will make some commands ignore imported commands, and some include them.
If you find that you want more control over when commands
get imported, you may wish to turn SHARE_HISTORY
off,
INC_APPEND_HISTORY
or INC_APPEND_HISTORY_TIME
(see above) on,
and then manually import commands whenever you need them using ‘fc
-RI
’.
ALL_EXPORT
(-a
, ksh: -a
) ¶All parameters subsequently defined are automatically exported.
GLOBAL_EXPORT
<Z> ¶If this option is set, passing the -x
flag to the builtins declare
,
float
, integer
, readonly
and typeset
(but not local
)
will also set the -g
flag; hence parameters exported to
the environment will not be made local to the enclosing function, unless
they were already or the flag +g
is given explicitly. If the option is
unset, exported parameters will be made local in just the same way as any
other parameter.
This option is set by default for backward compatibility; it is not
recommended that its behaviour be relied upon. Note that the builtin
export
always sets both the -x
and -g
flags, and hence its
effect extends beyond the scope of the enclosing function; this is the
most portable way to achieve this behaviour.
GLOBAL_RCS
(+d
) <D> ¶If this option is unset, the startup files /etc/zprofile
,
/etc/zshrc
, /etc/zlogin
and /etc/zlogout
will not be run. It
can be disabled and re-enabled at any time, including inside local startup
files (.zshrc
, etc.).
RCS
(+f
) <D> ¶After /etc/zshenv
is sourced on startup, source the
.zshenv
, /etc/zprofile
, .zprofile
,
/etc/zshrc
, .zshrc
, /etc/zlogin
, .zlogin
, and .zlogout
files, as described in Files.
If this option is unset, the /etc/zshenv
file is still sourced, but any
of the others will not be; it can be set at any time to prevent the
remaining startup files after the currently executing one from
being sourced.
ALIASES
<D> ¶Expand aliases.
CLOBBER
(+C
, ksh: +C
) <D> ¶Allows ‘>
’ redirection to truncate existing files.
Otherwise ‘>!
’ or ‘>|
’ must be used to truncate a file.
If the option is not set, and the option APPEND_CREATE
is also
not set, ‘>>!
’ or ‘>>|
’ must be used to create a file.
If either option is set, ‘>>
’ may be used.
CLOBBER_EMPTY
¶This option is only used if the option CLOBBER
is not set: note that
it is set by default.
If this option is set, then regular files of zero length may be ovewritten (‘clobbered’). Note that it is possible another process has written to the file between this test and use of the file by the current process. This option should therefore not be used in cases where files to be clobbered may be written to asynchronously.
CORRECT
(-0
) ¶Try to correct the spelling of commands.
Note that, when the HASH_LIST_ALL
option is not set or when some
directories in the path are not readable, this may falsely report spelling
errors the first time some commands are used.
The shell variable CORRECT_IGNORE
may be set to a pattern to
match words that will never be offered as corrections.
CORRECT_ALL
(-O
) ¶Try to correct the spelling of all arguments in a line.
The shell variable CORRECT_IGNORE_FILE
may be set to a pattern to
match file names that will never be offered as corrections.
DVORAK
¶Use the Dvorak keyboard instead of the standard qwerty keyboard as a basis
for examining spelling mistakes for the CORRECT
and CORRECT_ALL
options and the spell-word
editor command.
FLOW_CONTROL
<D> ¶If this option is unset, output flow control via start/stop characters (usually assigned to ^S/^Q) is disabled in the shell’s editor.
IGNORE_EOF
(-7
) ¶Do not exit on end-of-file. Require the use
of exit
or logout
instead.
However, ten consecutive EOFs will cause the shell to exit anyway,
to avoid the shell hanging if its tty goes away.
Also, if this option is set and the Zsh Line Editor is used, widgets implemented by shell functions can be bound to EOF (normally Control-D) without printing the normal warning message. This works only for normal widgets, not for completion widgets.
INTERACTIVE_COMMENTS
(-k
) <K> <S> ¶Allow comments even in interactive shells.
HASH_CMDS
<D> ¶Note the location of each command the first time it is executed.
Subsequent invocations of the same command will use the
saved location, avoiding a path search.
If this option is unset, no path hashing is done at all.
However, when CORRECT
is set, commands whose names do not appear in
the functions or aliases hash tables are hashed in order to avoid
reporting them as spelling errors.
HASH_DIRS
<D> ¶Whenever a command name is hashed, hash the directory containing it,
as well as all directories that occur earlier in the path.
Has no effect if neither HASH_CMDS
nor CORRECT
is set.
HASH_EXECUTABLES_ONLY
¶When hashing commands because of HASH_CMDS
, check that the
file to be hashed is actually an executable. This option
is unset by default as if the path contains a large number of commands,
or consists of many remote files, the additional tests can take
a long time. Trial and error is needed to show if this option is
beneficial.
MAIL_WARNING
(-U
) ¶Print a warning message if a mail file has been accessed since the shell last checked.
PATH_DIRS
(-Q
) ¶Perform a path search even on command names with slashes in them.
Thus if ‘/usr/local/bin
’ is in the user’s path, and he or she types
‘X11/xinit
’, the command ‘/usr/local/bin/X11/xinit
’ will be executed
(assuming it exists).
Commands explicitly beginning with ‘/
’, ‘./
’ or ‘../
’
are not subject to the path search.
This also applies to the ‘.
’ and source
builtins.
Note that subdirectories of the current directory are always searched for
executables specified in this form. This takes place before any search
indicated by this option, and regardless of whether ‘.
’ or the current
directory appear in the command search path.
PATH_SCRIPT
<K> <S> ¶If this option is not set, a script passed as the first non-option argument to the shell must contain the name of the file to open. If this option is set, and the script does not specify a directory path, the script is looked for first in the current directory, then in the command path. See Invocation.
PRINT_EIGHT_BIT
¶Print eight bit characters literally in completion lists, etc. This option is not necessary if your system correctly returns the printability of eight bit characters (see ctype(3)).
PRINT_EXIT_VALUE
(-1
) ¶Print the exit value of programs with non-zero exit status. This is only available at the command line in interactive shells.
RC_QUOTES
¶Allow the character sequence ‘{No value for `dsq'}
’ to signify a single quote
within singly quoted strings. Note this does not apply in quoted strings
using the format $'
...'
, where a backslashed single quote can
be used.
RM_STAR_SILENT
(-H
) <K> <S> ¶Do not query the user before executing ‘rm *
’ or ‘rm path/*
’.
RM_STAR_WAIT
¶If querying the user before executing ‘rm *
’ or ‘rm path/*
’,
first wait ten seconds and ignore anything typed in that time.
This avoids the problem of reflexively answering ‘yes’ to the query
when one didn’t really mean it. The wait and query can always be
avoided by expanding the ‘*
’ in ZLE (with tab).
SHORT_LOOPS
<C> <Z> ¶Allow the short forms of for
, repeat
, select
,
if
, and function
constructs.
SHORT_REPEAT
¶Allow the short form repeat
as SHORT_LOOPS
but without enabling
it for the other constructs.
SUN_KEYBOARD_HACK
(-L
) ¶If a line ends with a backquote, and there are an odd number
of backquotes on the line, ignore the trailing backquote.
This is useful on some keyboards where the return key is
too small, and the backquote key lies annoyingly close to it.
As an alternative the variable KEYBOARD_HACK
lets you choose the
character to be removed.
AUTO_CONTINUE
¶With this option set, stopped jobs that are removed from the job table
with the disown
builtin command are automatically sent a CONT
signal to make them running.
AUTO_RESUME
(-W
) ¶Treat single word simple commands without redirection as candidates for resumption of an existing job.
BG_NICE
(-6
) <C> <Z> ¶Run all background jobs at a lower priority. This option is set by default.
CHECK_JOBS
<Z> ¶Report the status of background and suspended jobs before exiting a shell
with job control; a second attempt to exit the shell will succeed.
NO_CHECK_JOBS
is best used only in combination with NO_HUP
, else
such jobs will be killed automatically.
The check is omitted if the commands run from the previous command line
included a ‘jobs
’ command, since it is assumed the user is aware that
there are background or suspended jobs. A ‘jobs
’ command run from one
of the hook functions defined in
the section ‘Special Functions’ in Functions
is not counted for this purpose.
CHECK_RUNNING_JOBS
<Z> ¶Check for both running and suspended jobs when CHECK_JOBS
is enabled.
When this option is disabled, zsh checks only for suspended jobs, which
matches the default behavior of bash.
This option has no effect unless CHECK_JOBS
is set.
HUP
<Z> ¶Send the HUP
signal to running jobs when the
shell exits.
LONG_LIST_JOBS
(-R
) ¶Print job notifications in the long format by default.
MONITOR
(-m
, ksh: -m
) ¶Allow job control. Set by default in interactive shells.
NOTIFY
(-5
, ksh: -b
) <Z> ¶Report the status of background jobs immediately, rather than waiting until just before printing a prompt.
POSIX_JOBS
<K> <S> ¶This option makes job control more compliant with the POSIX standard.
When the option is not set, the MONITOR
option is unset on entry to
subshells, so that job control is no longer active. When the option is
set, the MONITOR
option and job control remain active in the
subshell, but note that the subshell has no access to jobs in the parent
shell.
When the option is not set, jobs put in the background or foreground
with bg
or fg
are displayed with the same information that would
be reported by jobs
. When the option is set, only the text is
printed. The output from jobs
itself is not affected by the option.
When the option is not set, job information from the parent
shell is saved for output within a subshell (for example, within a
pipeline). When the option is set, the output of jobs
is empty
until a job is started within the subshell.
In previous versions of the shell, it was necessary to enable
POSIX_JOBS
in order for the builtin command wait
to return the
status of background jobs that had already exited. This is no longer
the case.
PROMPT_BANG
<K> ¶If set, ‘!
’ is treated specially in prompt expansion.
See
Prompt Expansion.
PROMPT_CR
(+V
) <D> ¶Print a carriage return just before printing a prompt in the line editor. This is on by default as multi-line editing is only possible if the editor knows where the start of the line appears.
PROMPT_SP
<D> ¶Attempt to preserve a partial line (i.e. a line that did not end with a
newline) that would otherwise be covered up by the command prompt due to
the PROMPT_CR
option. This works by outputting some cursor-control
characters, including a series of spaces, that should make the terminal
wrap to the next line when a partial line is present (note that this is
only successful if your terminal has automatic margins, which is typical).
When a partial line is preserved, by default you will see an inverse+bold
character at the end of the partial line: a ‘%
’ for a normal user or
a ‘#
’ for root. If set, the shell parameter PROMPT_EOL_MARK
can be
used to customize how the end of partial lines are shown.
NOTE: if the PROMPT_CR
option is not set, enabling this option will
have no effect. This option is on by default.
PROMPT_PERCENT
<C> <Z> ¶If set, ‘%
’ is treated specially in prompt expansion.
See
Prompt Expansion.
PROMPT_SUBST
<K> <S> ¶If set, parameter expansion, command substitution and arithmetic expansion are performed in prompts. Substitutions within prompts do not affect the command status.
TRANSIENT_RPROMPT
¶Remove any right prompt from display when accepting a command line. This may be useful with terminals with other cut/paste methods.
ALIAS_FUNC_DEF
<S> ¶By default, zsh does not allow the definition of functions using
the ‘name ()
’ syntax if name was expanded as an
alias: this causes an error. This is usually the desired behaviour, as
otherwise the combination of an alias and a function based on the same
definition can easily cause problems.
When this option is set, aliases can be used for defining functions.
For example, consider the following definitions as they might occur in a startup file.
alias foo=bar foo() { print This probably does not do what you expect. }
Here, foo
is expanded as an alias to bar
before the
()
is encountered, so the function defined would be named
bar
. By default this is instead an error in native mode. Note that
quoting any part of the function name, or using the keyword
function
, avoids the problem, so is recommended when the function
name can also be an alias.
C_BASES
¶Output hexadecimal numbers in the standard C format, for example ‘0xFF
’
instead of the usual ‘16#FF
’. If the option OCTAL_ZEROES
is also
set (it is not by default), octal numbers will be treated similarly and
hence appear as ‘077
’ instead of ‘8#77
’. This option has no effect
on the choice of the output base, nor on the output of bases other than
hexadecimal and octal. Note that these formats will be understood on input
irrespective of the setting of C_BASES
.
C_PRECEDENCES
¶This alters the precedence of arithmetic operators to be more like C and other programming languages; Arithmetic Evaluation has an explicit list.
DEBUG_BEFORE_CMD
<D> ¶Run the DEBUG
trap before each command; otherwise it is run after
each command. Setting this option mimics the behaviour of ksh 93; with
the option unset the behaviour is that of ksh 88.
ERR_EXIT
(-e
, ksh: -e
) ¶If a command has a non-zero exit status, execute the ZERR
trap, if set, and exit. This is disabled while running initialization
scripts.
The behaviour is also disabled inside DEBUG
traps. In this
case the option is handled specially: it is unset on entry to
the trap. If the option DEBUG_BEFORE_CMD
is set,
as it is by default, and the option ERR_EXIT
is found to have been set
on exit, then the command for which the DEBUG
trap is being executed is
skipped. The option is restored after the trap exits.
Non-zero status in a command list containing &&
or ||
is ignored
for commands not at the end of the list. Hence
false && true
does not trigger exit.
Exiting due to ERR_EXIT
has certain interactions with asynchronous
jobs noted in
Jobs & Signals.
ERR_RETURN
¶If a command has a non-zero exit status, return immediately from the
enclosing function. The logic is similar to that for ERR_EXIT
,
except that an implicit return
statement is executed instead of an
exit
. This will trigger an exit at the outermost level of a
non-interactive script.
Normally this option inherits the behaviour of ERR_EXIT
that
code followed by ‘&&
’ ‘||
’ does not trigger a return. Hence
in the following:
summit || true
no return is forced as the combined effect always has a zero return status.
Note. however, that if summit
in the above example is itself a
function, code inside it is considered separately: it may force a return
from summit
(assuming the option remains set within summit
), but
not from the enclosing context. This behaviour is different from
ERR_EXIT
which is unaffected by function scope.
EVAL_LINENO
<Z> ¶If set, line numbers of expressions evaluated using the builtin eval
are tracked separately of the enclosing environment. This applies both
to the parameter LINENO
and the line number output by the prompt
escape %i
. If the option is set, the prompt escape %N
will output
the string ‘(eval)
’ instead of the script or function name as an
indication. (The two prompt escapes are typically used in the parameter
PS4
to be output when the option XTRACE
is set.) If
EVAL_LINENO
is unset, the line number of the surrounding script or
function is retained during the evaluation.
EXEC
(+n
, ksh: +n
) <D> ¶Do execute commands. Without this option, commands are
read and checked for syntax errors, but not executed.
This option cannot be turned off in an interactive shell,
except when ‘-n
’ is supplied to the shell at startup.
FUNCTION_ARGZERO
<C> <Z> ¶When executing a shell function or sourcing a script, set $0
temporarily to the name of the function/script. Note that toggling
FUNCTION_ARGZERO
from on to off (or off to on) does not change the
current value of $0
. Only the state upon entry to the function or
script has an effect. Compare POSIX_ARGZERO
.
LOCAL_LOOPS
¶When this option is not set, the effect of break
and continue
commands may propagate outside function scope, affecting loops in
calling functions. When the option is set in a calling function, a
break
or a continue
that is not caught within a called function
(regardless of the setting of the option within that function)
produces a warning and the effect is cancelled.
LOCAL_OPTIONS
<K> ¶If this option is set at the point of return from a shell function,
most options (including this one) which were in force upon entry to
the function are restored; options that are not restored are
PRIVILEGED
and RESTRICTED
. Otherwise, only this option,
and the LOCAL_LOOPS
, XTRACE
and PRINT_EXIT_VALUE
options are
restored. Hence if this is explicitly unset by a shell function the
other options in force at the point of return will remain so.
A shell function can also guarantee itself a known shell configuration
with a formulation like ‘emulate -L zsh
’; the -L
activates
LOCAL_OPTIONS
.
LOCAL_PATTERNS
¶If this option is set at the point of return from a shell function,
the state of pattern disables, as set with the builtin command
‘disable -p
’, is restored to what it was when the function was
entered. The behaviour of this option is similar to the effect
of LOCAL_OPTIONS
on options; hence ‘emulate -L sh
’ (or
indeed any other emulation with the -L
option) activates
LOCAL_PATTERNS
.
LOCAL_TRAPS
<K> ¶If this option is set when a signal trap is set inside a function, then the
previous status of the trap for that signal will be restored when the
function exits. Note that this option must be set prior to altering the
trap behaviour in a function; unlike LOCAL_OPTIONS
, the value on exit
from the function is irrelevant. However, it does not need to be set
before any global trap for that to be correctly restored by a function.
For example,
unsetopt localtraps trap - INT fn() { setopt localtraps; trap {No value for `dsq'} INT; sleep 3; }
will restore normal handling of SIGINT
after the function exits.
MULTI_FUNC_DEF
<Z> ¶Allow definitions of multiple functions at once in the form ‘fn1
fn2
...()
’; if the option is not set, this causes
a parse error. Definition of multiple functions with the function
keyword is always allowed. Multiple function definitions are not often
used and can cause obscure errors.
MULTIOS
<Z> ¶Perform implicit tees or cats when multiple redirections are attempted (see Redirection).
OCTAL_ZEROES
<S> ¶Interpret any integer constant beginning with a 0 as octal, per IEEE Std 1003.2-1992 (ISO 9945-2:1993). This is not enabled by default as it causes problems with parsing of, for example, date and time strings with leading zeroes.
Sequences of digits indicating a numeric base such as the ‘08
’
component in ‘08#77
’ are always interpreted as decimal, regardless
of leading zeroes.
PIPE_FAIL
¶By default, when a pipeline exits the exit status recorded by the shell
and returned by the shell variable $?
reflects that of the
rightmost element of a pipeline. If this option is set, the exit status
instead reflects the status of the rightmost element of the pipeline
that was non-zero, or zero if all elements exited with zero status.
SOURCE_TRACE
¶If set, zsh will print an informational message announcing the name of
each file it loads. The format of the output is similar to that
for the XTRACE
option, with the message <sourcetrace>
.
A file may be loaded by the shell itself when it
starts up and shuts down (Startup/Shutdown Files
) or by the use of
the ‘source
’ and ‘dot
’ builtin commands.
TYPESET_SILENT
¶If this is unset, executing any of the ‘typeset
’ family of
commands with no options and a list of parameters that have no values
to be assigned but already exist will display the value of the parameter.
If the option is set, they will only be shown when parameters are selected
with the ‘-m
’ option. The option ‘-p
’ is available whether or not
the option is set.
TYPESET_TO_UNSET
<K> <S> ¶When declaring a new parameter with any of the ‘typeset
’ family of
related commands, the parameter remains unset unless and until a
value is explicity assigned to it, either in the ‘typeset
’ command
itself or as a later assignment statement.
VERBOSE
(-v
, ksh: -v
) ¶Print shell input lines as they are read.
XTRACE
(-x
, ksh: -x
) ¶Print commands and their arguments as they are executed. The
output is preceded by the value of $PS4
, formatted as described
in
Prompt Expansion.
APPEND_CREATE
<K> <S> ¶This option only applies when NO_CLOBBER
(-C
) is in effect.
If this option is not set, the shell will report an error when a
append redirection (>>
) is used on a file that does not already
exists (the traditional zsh behaviour of NO_CLOBBER
). If the option
is set, no error is reported (POSIX behaviour).
BASH_REMATCH
¶When set, matches performed with the =~
operator will set the
BASH_REMATCH
array variable, instead of the default MATCH
and
match
variables. The first element of the BASH_REMATCH
array
will contain the entire matched text and subsequent elements will contain
extracted substrings. This option makes more sense when KSH_ARRAYS
is
also set, so that the entire matched portion is stored at index 0 and the
first substring is at index 1. Without this option, the MATCH
variable
contains the entire matched text and the match
array variable contains
substrings.
BSD_ECHO
<S> ¶Make the echo
builtin compatible with the BSD echo(1) command.
This disables backslashed escape sequences in echo strings unless the
-e
option is specified.
CONTINUE_ON_ERROR
¶If a fatal error is encountered (see Errors), and the code is running in a script, the shell will resume execution at the next statement in the script at the top level, in other words outside all functions or shell constructs such as loops and conditions. This mimics the behaviour of interactive shells, where the shell returns to the line editor to read a new command; it was the normal behaviour in versions of zsh before 5.0.1.
CSH_JUNKIE_HISTORY
<C> ¶A history reference without an event specifier will always refer to the previous command. Without this option, such a history reference refers to the same event as the previous history reference on the current command line, defaulting to the previous command.
CSH_JUNKIE_LOOPS
<C> ¶Allow loop bodies to take the form ‘list; end
’ instead of
‘do
list; done
’.
CSH_JUNKIE_QUOTES
<C> ¶Changes the rules for single- and double-quoted text to match that of
csh. These require that embedded newlines be preceded by a backslash;
unescaped newlines will cause an error message.
In double-quoted strings, it is made impossible to escape ‘$
’, ‘`
’
or ‘"
’ (and ‘\
’ itself no longer needs escaping).
Command substitutions are only expanded once, and cannot be nested.
CSH_NULLCMD
<C> ¶Do not use the values of NULLCMD
and READNULLCMD
when running redirections with no command. This make
such redirections fail (see Redirection).
KSH_ARRAYS
<K> <S> ¶Emulate ksh array handling as closely as possible. If this option
is set, array elements are numbered from zero, an array parameter
without subscript refers to the first element instead of the whole array,
and braces are required to delimit a subscript (‘${path[2]}
’ rather
than just ‘$path[2]
’) or to apply modifiers to any parameter
(‘${PWD:h}
’ rather than ‘$PWD:h
’).
KSH_AUTOLOAD
<K> <S> ¶Emulate ksh function autoloading. This means that when a function is autoloaded, the corresponding file is merely executed, and must define the function itself. (By default, the function is defined to the contents of the file. However, the most common ksh-style case - of the file containing only a simple definition of the function - is always handled in the ksh-compatible manner.)
KSH_OPTION_PRINT
<K> ¶Alters the way options settings are printed: instead of separate lists of set and unset options, all options are shown, marked ‘on’ if they are in the non-default state, ‘off’ otherwise.
KSH_TYPESET
¶This option is now obsolete: a better appropximation to the behaviour of
other shells is obtained with the reserved word interface to
declare
, export
, float
, integer
, local
, readonly
and typeset
. Note that the option is only applied when the reserved
word interface is not in use.
Alters the way arguments to the typeset
family of commands, including
declare
, export
, float
, integer
, local
and
readonly
, are processed. Without this option, zsh will perform normal
word splitting after command and parameter expansion in arguments of an
assignment; with it, word splitting does not take place in those cases.
KSH_ZERO_SUBSCRIPT
¶Treat use of a subscript of value zero in array or string expressions as a
reference to the first element, i.e. the element that usually has the
subscript 1. Ignored if KSH_ARRAYS
is also set.
If neither this option nor KSH_ARRAYS
is set, accesses to an element of
an array or string with subscript zero return an empty element or string,
while attempts to set element zero of an array or string are treated as an
error. However, attempts to set an otherwise valid subscript range that
includes zero will succeed. For example, if KSH_ZERO_SUBSCRIPT
is not
set,
array[0]=(element)
is an error, while
array[0,1]=(element)
is not and will replace the first element of the array.
This option is for compatibility with older versions of the shell and is not recommended in new code.
POSIX_ALIASES
<K> <S> ¶When this option is set, reserved words are not candidates for alias expansion: it is still possible to declare any of them as an alias, but the alias will never be expanded. Reserved words are described in Reserved Words.
Alias expansion takes place while text is being read; hence when this
option is set it does not take effect until the end of any function or
other piece of shell code parsed as one unit. Note this may
cause differences from other shells even when the option is in
effect. For example, when running a command with ‘zsh -c
’,
or even ‘zsh -o posixaliases -c
’, the entire command argument is parsed
as one unit, so aliases defined within the argument are not available even
in later lines. If in doubt, avoid use of aliases in non-interactive
code.
POSIX_ARGZERO
¶This option may be used to temporarily disable FUNCTION_ARGZERO
and
thereby restore the value of $0
to the name used to invoke the shell
(or as set by the -c
command line option). For compatibility with
previous versions of the shell, emulations use NO_FUNCTION_ARGZERO
instead of POSIX_ARGZERO
, which may result in unexpected scoping of
$0
if the emulation mode is changed inside a function or script.
To avoid this, explicitly enable POSIX_ARGZERO
in the emulate
command:
emulate sh -o POSIX_ARGZERO
Note that NO_POSIX_ARGZERO
has no effect unless FUNCTION_ARGZERO
was already enabled upon entry to the function or script.
POSIX_BUILTINS
<K> <S> ¶When this option is set the command
builtin can be used to execute
shell builtin commands. Parameter assignments specified before shell
functions and special builtins are kept after the command completes unless
the special builtin is prefixed with the command
builtin. Special
builtins are
.
,
:
,
break
,
continue
,
declare
,
eval
,
exit
,
export
,
integer
,
local
,
readonly
,
return
,
set
,
shift
,
source
,
times
,
trap
and
unset
.
In addition, various error conditions associated with the above builtins
or exec
cause a non-interactive shell to exit and an interactive
shell to return to its top-level processing.
Furthermore, functions and shell builtins are not executed after
an exec
prefix; the command to be executed must be an external
command found in the path.
Furthermore, the getopts
builtin behaves in a POSIX-compatible
fashion in that the associated variable OPTIND
is not made
local to functions, and its value is calculated differently to match
other shells.
Moreover, the warning and special exit code from
[[ -o
non_existent_option ]]
are suppressed.
POSIX_IDENTIFIERS
<K> <S> ¶When this option is set, only the ASCII characters a
to z
, A
to
Z
, 0
to 9
and _
may be used in identifiers (names
of shell parameters and modules).
In addition, setting this option limits the effect of parameter
substitution with no braces, so that the expression $#
is treated as
the parameter $#
even if followed by a valid parameter name.
When it is unset, zsh allows expressions of the form $#
name
to refer to the length of $
name, even for special variables,
for example in expressions such as $#-
and $#*
.
Another difference is that with the option set assignment to an
unset variable in arithmetic context causes the variable to be created
as a scalar rather than a numeric type. So after ‘unset t; (( t = 3
))
’. without POSIX_IDENTIFIERS
set t
has integer type, while with
it set it has scalar type.
When the option is unset and multibyte character support is enabled (i.e. it
is compiled in and the option MULTIBYTE
is set), then additionally any
alphanumeric characters in the local character set may be used in
identifiers. Note that scripts and functions written with this feature are
not portable, and also that both options must be set before the script
or function is parsed; setting them during execution is not sufficient
as the syntax variable=
value has already been parsed as
a command rather than an assignment.
If multibyte character support is not compiled into the shell this option is ignored; all octets with the top bit set may be used in identifiers. This is non-standard but is the traditional zsh behaviour.
POSIX_STRINGS
<K> <S> ¶This option affects processing of quoted strings. Currently it only affects the behaviour of null characters, i.e. character 0 in the portable character set corresponding to US ASCII.
When this option is not set, null characters embedded within strings
of the form $'
...'
are treated as ordinary characters. The
entire string is maintained within the shell and output to files where
necessary, although owing to restrictions of the library interface
the string is truncated at the null character in file names, environment
variables, or in arguments to external programs.
When this option is set, the $'
...'
expression is truncated at
the null character. Note that remaining parts of the same string
beyond the termination of the quotes are not truncated.
For example, the command line argument a$'b\0c'd
is treated with
the option off as the characters a
, b
, null, c
, d
,
and with the option on as the characters a
, b
, d
.
POSIX_TRAPS
<K> <S> ¶When this option is set, the usual zsh behaviour of executing
traps for EXIT
on exit from shell functions is suppressed.
In that case, manipulating EXIT
traps always alters the global
trap for exiting the shell; the LOCAL_TRAPS
option is
ignored for the EXIT
trap.
Also, a return
statement executed in a trap with no argument passes
back from the function the value from the surrounding context, not from
code executed within the trap.
Furthermore, if a trap is set to be ignored, this state persists when a subshell is entered. Without the option, the trap would be reset to its default state at this point.
SH_FILE_EXPANSION
<K> <S> ¶Perform filename expansion (e.g., ~
expansion) before
parameter expansion, command substitution, arithmetic expansion
and brace expansion.
If this option is unset, it is performed after
brace expansion, so things like ‘~$USERNAME
’ and
‘~{pfalstad,rc}
’ will work.
SH_NULLCMD
<K> <S> ¶Do not use the values of NULLCMD
and READNULLCMD
when doing redirections, use ‘:
’ instead (see Redirection).
SH_OPTION_LETTERS
<K> <S> ¶If this option is set the shell tries to interpret single letter options
(which are used with set
and setopt
) like ksh does.
This also affects the value of the -
special parameter.
SH_WORD_SPLIT
(-y
) <K> <S> ¶Causes field splitting to be performed on unquoted parameter expansions. Note that this option has nothing to do with word splitting. (See Parameter Expansion.)
TRAPS_ASYNC
¶While waiting for a program to exit, handle signals and run traps immediately. Otherwise the trap is run after a child process has exited. Note this does not affect the point at which traps are run for any case other than when the shell is waiting for a child process.
INTERACTIVE
(-i
, ksh: -i
) ¶This is an interactive shell. This option is set upon initialisation if
the standard input is a tty and commands are being read from standard input.
(See the discussion of SHIN_STDIN
.)
This heuristic may be overridden by specifying a state for this option
on the command line.
The value of this option can only be changed via flags supplied at
invocation of the shell.
It cannot be changed once zsh is running.
LOGIN
(-l
, ksh: -l
) ¶This is a login shell.
If this option is not explicitly set, the shell becomes a login shell if
the first character of the argv[0]
passed to the shell is a ‘-
’.
PRIVILEGED
(-p
, ksh: -p
) ¶Turn on privileged mode. Typically this is used when script is to be run
with elevated privileges. This should be done as follows directly with
the -p
option to zsh so that it takes effect during startup.
#!/bin/zsh -p
The option is enabled automatically on startup if the effective user (group) ID is not equal to the real user (group) ID. In this case, turning the option off causes the effective user and group IDs to be set to the real user and group IDs. Be aware that if that fails the shell may be running with different IDs than was intended so a script should check for failure and act accordingly, for example:
unsetopt privileged || exit
The PRIVILEGED
option disables sourcing user startup files.
If zsh is invoked as ‘sh
’ or ‘ksh
’ with this option set,
/etc/suid_profile
is sourced (after /etc/profile
on interactive
shells). Sourcing ~/.profile
is disabled and the contents of the
ENV
variable is ignored. This option cannot be changed using the
-m
option of setopt
and unsetopt
, and changing it inside a
function always changes it globally regardless of the LOCAL_OPTIONS
option.
RESTRICTED
(-r
) ¶Enables restricted mode. This option cannot be changed using
unsetopt
, and setting it inside a function always changes it
globally regardless of the LOCAL_OPTIONS
option. See
Restricted Shell.
SHIN_STDIN
(-s
, ksh: -s
) ¶Commands are being read from the standard input.
Commands are read from standard input if no command is specified with
-c
and no file of commands is specified. If SHIN_STDIN
is set explicitly on the command line,
any argument that would otherwise have been
taken as a file to run will instead be treated as a normal positional
parameter.
Note that setting or unsetting this option on the command line does not
necessarily affect the state the option will have while the shell is
running - that is purely an indicator of whether or not commands are
actually being read from standard input.
The value of this option can only be changed via flags supplied at
invocation of the shell.
It cannot be changed once zsh is running.
SINGLE_COMMAND
(-t
, ksh: -t
) ¶If the shell is reading from standard input, it exits after a single command
has been executed. This also makes the shell non-interactive, unless the
INTERACTIVE
option is explicitly set on the command line.
The value of this option can only be changed via flags supplied at
invocation of the shell.
It cannot be changed once zsh is running.
BEEP
(+B
) <D> ¶Beep on error in ZLE.
COMBINING_CHARS
¶Assume that the terminal displays combining characters correctly. Specifically, if a base alphanumeric character is followed by one or more zero-width punctuation characters, assume that the zero-width characters will be displayed as modifications to the base character within the same width. Not all terminals handle this. If this option is not set, zero-width characters are displayed separately with special mark-up.
If this option is set, the pattern test [[:WORD:]]
matches a
zero-width punctuation character on the assumption that it will be
used as part of a word in combination with a word character.
Otherwise the base shell does not handle combining characters specially.
EMACS
¶If ZLE is loaded, turning on this option has the equivalent effect
of ‘bindkey -e
’. In addition, the VI option is unset.
Turning it off has no effect. The option setting is
not guaranteed to reflect the current keymap. This option is
provided for compatibility; bindkey
is the recommended interface.
OVERSTRIKE
¶Start up the line editor in overstrike mode.
SINGLE_LINE_ZLE
(-M
) <K> ¶Use single-line command line editing instead of multi-line.
Note that although this is on by default in ksh emulation it only provides superficial compatibility with the ksh line editor and reduces the effectiveness of the zsh line editor. As it has no effect on shell syntax, many users may wish to disable this option when using ksh emulation interactively.
VI
¶If ZLE is loaded, turning on this option has the equivalent effect
of ‘bindkey -v
’. In addition, the EMACS option is unset.
Turning it off has no effect. The option setting is
not guaranteed to reflect the current keymap. This option is
provided for compatibility; bindkey
is the recommended interface.
ZLE
(-Z
) ¶Use the zsh line editor. Set by default in interactive shells connected to a terminal.
Some options have alternative names. These aliases are never used for output, but can be used just like normal option names when specifying options to the shell.
BRACE_EXPAND
¶NO_IGNORE_BRACES
(ksh and bash compatibility)
DOT_GLOB
¶GLOB_DOTS
(bash compatibility)
HASH_ALL
¶HASH_CMDS
(bash compatibility)
HIST_APPEND
¶APPEND_HISTORY
(bash compatibility)
HIST_EXPAND
¶BANG_HIST
(bash compatibility)
LOG
¶NO_HIST_NO_FUNCTIONS
(ksh compatibility)
MAIL_WARN
¶MAIL_WARNING
(bash compatibility)
ONE_CMD
¶SINGLE_COMMAND
(bash compatibility)
PHYSICAL
¶CHASE_LINKS
(ksh and bash compatibility)
PROMPT_VARS
¶PROMPT_SUBST
(bash compatibility)
STDIN
¶SHIN_STDIN
(ksh compatibility)
TRACK_ALL
¶HASH_CMDS
(ksh compatibility)
-0
CORRECT
-1
PRINT_EXIT_VALUE
-2
NO_BAD_PATTERN
-3
NO_NOMATCH
-4
GLOB_DOTS
-5
NOTIFY
-6
BG_NICE
-7
IGNORE_EOF
-8
MARK_DIRS
-9
AUTO_LIST
-B
NO_BEEP
-C
NO_CLOBBER
-D
PUSHD_TO_HOME
-E
PUSHD_SILENT
-F
NO_GLOB
-G
NULL_GLOB
-H
RM_STAR_SILENT
-I
IGNORE_BRACES
-J
AUTO_CD
-K
NO_BANG_HIST
-L
SUN_KEYBOARD_HACK
-M
SINGLE_LINE_ZLE
-N
AUTO_PUSHD
-O
CORRECT_ALL
-P
RC_EXPAND_PARAM
-Q
PATH_DIRS
-R
LONG_LIST_JOBS
-S
REC_EXACT
-T
CDABLE_VARS
-U
MAIL_WARNING
-V
NO_PROMPT_CR
-W
AUTO_RESUME
-X
LIST_TYPES
-Y
MENU_COMPLETE
-Z
ZLE
-a
ALL_EXPORT
-e
ERR_EXIT
-f
NO_RCS
-g
HIST_IGNORE_SPACE
-h
HIST_IGNORE_DUPS
-i
INTERACTIVE
-k
INTERACTIVE_COMMENTS
-l
LOGIN
-m
MONITOR
-n
NO_EXEC
-p
PRIVILEGED
-r
RESTRICTED
-s
SHIN_STDIN
-t
SINGLE_COMMAND
-u
NO_UNSET
-v
VERBOSE
-w
CHASE_LINKS
-x
XTRACE
-y
SH_WORD_SPLIT
-C
NO_CLOBBER
-T
TRAPS_ASYNC
-X
MARK_DIRS
-a
ALL_EXPORT
-b
NOTIFY
-e
ERR_EXIT
-f
NO_GLOB
-i
INTERACTIVE
-l
LOGIN
-m
MONITOR
-n
NO_EXEC
-p
PRIVILEGED
-r
RESTRICTED
-s
SHIN_STDIN
-t
SINGLE_COMMAND
-u
NO_UNSET
-v
VERBOSE
-x
XTRACE
-A
Used by set
for setting arrays
-b
Used on the command line to specify end of option processing
-c
Used on the command line to specify a single command
-m
Used by setopt
for pattern-matching option setting
-o
Used in all places to allow use of long option names
-s
Used by set
to sort positional parameters
Some shell builtin commands take options as described in individual
entries; these are often referred to in the list below as ‘flags
’ to
avoid confusion with shell options, which may also have an effect on the
behaviour of builtin commands. In this introductory section,
‘option
’ always has the meaning of an option to a command that should
be familiar to most command line users.
Typically, options are single letters preceded by a hyphen (-
).
Options that take an argument accept it either immediately following the
option letter or after white space, for example ‘print -C3 {1..9}
’ or
‘print -C 3 {1..9}
’ are equivalent. Arguments to options are not the
same as arguments to the command; the documentation indicates which is
which. Options that do not take an argument may be combined in a single
word, for example ‘print -rca -- *
’ and ‘print -r -c -a -- *
’ are
equivalent.
Some shell builtin commands also take options that begin with ‘+
’
instead of ‘-
’. The list below makes clear which commands these
are.
Options (together with their individual arguments, if any) must appear in a group before any non-option arguments; once the first non-option argument has been found, option processing is terminated.
All builtin commands other than ‘echo
’ and precommand modifiers,
even those that have no options, can be given the argument ‘-
-
’
to terminate option processing. This indicates that the following words
are non-option arguments, but is otherwise ignored. This is useful in
cases where arguments to the command may begin with ‘-
’. For
historical reasons, most builtin commands (including ‘echo
’) also
recognize a single ‘-
’ in a separate word for this purpose; note
that this is less standard and use of ‘-
-
’ is recommended.
-
simple commandSee Precommand Modifiers.
.
file [ arg ... ] ¶Read commands from file and execute them in the current shell environment.
If file does not contain a slash, or if PATH_DIRS
is set,
the shell looks in the components of $path
to find the directory
containing file. Files in the current directory are not read
unless ‘.
’ appears somewhere in $path
. If a file named
‘file.zwc
’ is found, is newer than file, and is the
compiled form (created with the zcompile
builtin) of file,
then commands are read from that file instead of file.
If any arguments arg are given, they become the positional parameters; the old positional parameters are restored when the file is done executing. However, if no arguments are given, the positional parameters remain those of the calling context, and no restoring is done.
If file was not found the return status is 127; if file was found but contained a syntax error the return status is 126; else the return status is the exit status of the last command executed.
:
[ arg ... ] ¶This command does nothing, although normal argument expansions is performed which may have effects on shell parameters. A zero exit status is returned.
alias
[ {+
|-
}gmrsL
] [ name[=
value] ... ] ¶For each name with a corresponding value, define an alias
with that value. A trailing space in value causes the next word
to be checked for alias expansion. If the -g
flag is present,
define a global alias; global aliases are expanded even if they do not
occur in command position:
% perldoc --help 2>&1 | grep 'built-in functions' -f Search Perl built-in functions % alias -g HG='--help 2>&1 | grep' % perldoc HG 'built-in functions' -f Search Perl built-in functions
If the -s
flag is present, define a suffix alias: if the command
word on a command line is in the form ‘text.
name’, where
text is any non-empty string, it is replaced by the text
‘value text.
name’. Note that name is treated as
a literal string, not a pattern. A trailing space in value is not
special in this case. For example,
alias -s ps='gv --'
will cause the command ‘*.ps
’ to be expanded to ‘gv -- *.ps
’. As
alias expansion is carried out earlier than globbing, the ‘*.ps
’ will
then be expanded. Suffix aliases constitute a different name space from
other aliases (so in the above example it is still possible
to create an alias for the command ps
) and the two sets are never
listed together.
For each name with no value,
print the value of name, if any. With no arguments, print all
currently defined aliases other than suffix aliases. If the -m
flag
is given the arguments are taken as patterns (they should be quoted to
preserve them from being interpreted as glob patterns), and the aliases
matching these patterns are printed. When printing aliases and one of
the -g
, -r
or -s
flags is present, restrict the printing to
global, regular or suffix aliases, respectively; a regular alias is one
which is neither a global nor a suffix alias. Using ‘+
’
instead of ‘-
’, or ending the option list with a single
‘+
’, prevents the values of the aliases from being printed.
If the -L
flag is present, then print each
alias in a manner suitable for putting in a startup script. The exit
status is nonzero if a name (with no value) is given for
which no alias has been defined.
For more on aliases, include common problems, see Aliasing.
autoload
[ {+
|-
}RTUXdkmrtWz
] [ -w
] [ name ... ] ¶See the section ‘Autoloading Functions’ in Functions for full details. The fpath
parameter
will be searched to find the function definition when the function is
first referenced.
If name consists of an absolute path, the function is defined to
load from the file given (searching as usual for dump files in the given
location). The name of the function is the basename (non-directory
part) of the file. It is normally an error if the function is not found
in the given location; however, if the option -d
is given, searching
for the function defaults to $fpath
. If a function is loaded by
absolute path, any functions loaded from it that are marked for
autoload
without an absolute path have the load path of the parent
function temporarily prepended to $fpath
.
If the option -r
or -R
is given, the function is searched for
immediately and the location is recorded internally for use when the
function is executed; a relative path is expanded using the value of
$PWD
. This protects against a change to $fpath
after the call
to autoload
. With -r
, if the function is not found, it is
silently left unresolved until execution; with -R
, an error message
is printed and command processing aborted immediately the search fails,
i.e. at the autoload
command rather than at function execution..
The flag -X
may be used only inside a shell function. It causes the
calling function to be marked for autoloading and then immediately
loaded and executed, with the current array of positional parameters as
arguments. This replaces the previous definition of the function. If
no function definition is found, an error is printed and the function
remains undefined and marked for autoloading. If an argument is given,
it is used as a directory (i.e. it does not include the name of the
function) in which the function is to be found; this may be combined
with the -d
option to allow the function search to default to $fpath
if it is not in the given location.
The flag +X
attempts to load each name as an autoloaded function,
but does not execute it. The exit status is zero (success) if the
function was not previously defined and a definition for it was found.
This does not replace any existing definition of the function. The
exit status is nonzero (failure) if the function was already defined or
when no definition was found. In the latter case the function remains
undefined and marked for autoloading. If ksh-style autoloading is
enabled, the function created will contain the contents of the file
plus a call to the function itself appended to it, thus giving normal
ksh autoloading behaviour on the first call to the function.
If the -m
flag is also given each name is treated as a
pattern and all functions already marked for autoload that match the
pattern are loaded.
With the -t
flag, turn on execution tracing; with -T
, turn on
execution tracing only for the current function, turning it off on entry
to any called functions that do not also have tracing enabled.
With the -U
flag, alias expansion is suppressed when the function is
loaded.
With the -w
flag, the names are taken as names of files compiled
with the zcompile
builtin, and all functions defined in them are
marked for autoloading.
The flags -z
and -k
mark the function to be autoloaded using the
zsh or ksh style, as if the option KSH_AUTOLOAD
were unset or were
set, respectively. The flags override the setting of the option at the
time the function is loaded.
Note that the autoload
command makes no attempt to ensure the
shell options set during the loading or execution of the file have
any particular value. For this, the emulate
command can be used:
emulate zsh -c 'autoload -Uz func'
arranges that when func is loaded the shell is in native zsh
emulation, and this emulation is also applied when func is run.
Some of the functions of autoload
are also provided by functions
-u
or functions -U
, but autoload
is a more comprehensive
interface.
bg
[ job ... ] ¶&
Put each specified job in the background, or the current job if none is specified.
bindkey
See Zle Builtins.
break
[ n ] ¶Exit from an enclosing for
, while
,
until
, select
or repeat
loop. If an arithmetic expression n
is specified, then break n levels instead of just one.
builtin
name [ args ... ] ¶Executes the builtin name, with the given args.
bye
¶Same as exit
.
cap
See The zsh/cap Module.
cd
[ -qsLP
] [ arg ] ¶cd
[ -qsLP
] old newcd
[ -qsLP
] {+
|-
}nChange the current directory. In the first form, change the
current directory to arg, or to the value of $HOME
if
arg is not specified. If arg is ‘-
’, change to the
previous directory.
Otherwise, if arg begins with a slash, attempt to change to the directory given by arg.
If arg does not begin with a slash, the behaviour depends on whether
the current directory ‘.
’ occurs in the list of directories contained
in the shell parameter cdpath
. If it does not, first attempt to change
to the directory arg under the current directory, and if that fails
but cdpath
is set and contains at least one element attempt to change
to the directory arg under each component of cdpath
in turn until
successful. If ‘.
’ occurs in cdpath
, then cdpath
is searched
strictly in order so that ‘.
’ is only tried at the appropriate point.
The order of testing cdpath
is modified if the option POSIX_CD
is set, as described in the documentation for the option.
If no directory is found, the option CDABLE_VARS
is set, and a
parameter named arg exists whose value begins with a slash, treat its
value as the directory. In that case, the parameter is added to the named
directory hash table.
The second form of cd
substitutes the string new
for the string old in the name of the current directory,
and tries to change to this new directory.
The third form of cd
extracts an entry from the directory
stack, and changes to that directory. An argument of the form
‘+
n’ identifies a stack entry by counting from the left
of the list shown by the dirs
command, starting with zero.
An argument of the form ‘-
n’ counts from the right.
If the PUSHD_MINUS
option is set, the meanings of ‘+
’
and ‘-
’ in this context are swapped.
If the POSIX_CD
option is set, this form of cd
is not recognised
and will be interpreted as the first form.
If the -q
(quiet) option is specified, the hook function chpwd
and the functions in the array chpwd_functions
are not called.
This is useful for calls to cd
that do not change the environment
seen by an interactive user.
If the -s
option is specified, cd
refuses to change the current
directory if the given pathname contains symlinks. If the -P
option
is given or the CHASE_LINKS
option is set, symbolic links are resolved
to their true values. If the -L
option is given symbolic links are
retained in the directory (and not resolved) regardless of the state of
the CHASE_LINKS
option.
chdir
¶Same as cd
.
clone
See The zsh/clone Module.
command
[ -pvV
] simple command ¶The simple command argument is taken as an external command instead of
a function or builtin and is executed. If the POSIX_BUILTINS
option
is set, builtins will also be executed but certain special properties
of them are suppressed. The -p
flag causes a default path to be
searched instead of that in $path
. With the -v
flag, command
is similar to whence
and with -V
, it is equivalent to whence
-v
.
See also Precommand Modifiers.
comparguments
compcall
compctl
compdescribe
compfiles
compgroups
compquote
comptags
comptry
compvalues
continue
[ n ] ¶Resume the next iteration of the enclosing
for
, while
, until
, select
or
repeat
loop. If an arithmetic expression n is specified, break out of
n-1 loops and resume at the nth enclosing loop.
declare
¶Same as typeset
.
dirs
[ -c
] [ arg ... ] ¶dirs
[ -lpv
]With no arguments, print the contents of the directory stack.
Directories are added to this stack with the pushd
command,
and removed with the cd
or popd
commands.
If arguments are specified, load them onto the directory stack,
replacing anything that was there, and push the current directory
onto the stack.
-c
clear the directory stack.
-l
print directory names in full instead of using of using ~
expressions (Filename Expansion).
-p
print directory entries one per line.
-v
number the directories in the stack when printing.
disable
[ -afmprs
] name ... ¶Temporarily disable the named hash table elements or patterns. The default
is to disable builtin commands. This allows you to use an external
command with the same name as a builtin command. The -a
option
causes disable
to act on regular or global aliases. The -s
option causes disable
to act on suffix aliases. The -f
option causes
disable
to act on shell functions. The -r
options causes
disable
to act on reserved words. Without arguments all disabled
hash table elements from the corresponding hash table are printed.
With the -m
flag the arguments are taken as patterns (which should be
quoted to prevent them from undergoing filename expansion), and all hash
table elements from the corresponding hash table matching these patterns
are disabled. Disabled objects can be enabled with the enable
command.
With the option -p
, name ... refer to elements of the
shell’s pattern syntax as described in Filename Generation.
Certain elements can be disabled separately, as given below.
Note that patterns
not allowed by the current settings for the options EXTENDED_GLOB
,
KSH_GLOB
and SH_GLOB
are never enabled, regardless of the
setting here. For example, if EXTENDED_GLOB
is not active,
the pattern ^
is ineffective even if ‘disable -p "^"
’ has
not been issued. The list below indicates any option settings
that restrict the use of the pattern. It should be noted that
setting SH_GLOB
has a wider effect than merely disabling patterns
as certain expressions, in particular those involving parentheses,
are parsed differently.
The following patterns may be disabled; all the strings need quoting on the command line to prevent them from being interpreted immediately as patterns and the patterns are shown below in single quotes as a reminder.
'?'
The pattern character ?
wherever it occurs, including when preceding
a parenthesis with KSH_GLOB
.
'*'
The pattern character *
wherever it occurs, including recursive
globbing and when preceding a parenthesis with KSH_GLOB
.
'['
Character classes.
'<'
(NO_SH_GLOB
)Numeric ranges.
'|'
(NO_SH_GLOB
)Alternation in grouped patterns, case statements, or KSH_GLOB parenthesised expressions.
'('
(NO_SH_GLOB
)Grouping using single parentheses. Disabling this does not disable the
use of parentheses for KSH_GLOB
where they are introduced by a
special character, nor for glob qualifiers (use ‘setopt
NO_BARE_GLOB_QUAL
’ to disable glob qualifiers that use parentheses
only).
'~'
(EXTENDED_GLOB
)Exclusion in the form A~
B.
'^'
(EXTENDED_GLOB
)Exclusion in the form A^
B.
'#'
(EXTENDED_GLOB
)The pattern character #
wherever it occurs, both for
repetition of a previous pattern and for indicating globbing flags.
'?('
(KSH_GLOB
)The grouping form ?(
...)
. Note this is also
disabled if '?'
is disabled.
'*('
(KSH_GLOB
)The grouping form *(
...)
. Note this is also
disabled if '*'
is disabled.
'+('
(KSH_GLOB
)The grouping form +(
...)
.
'!('
(KSH_GLOB
)The grouping form !(
...)
.
'@('
(KSH_GLOB
)The grouping form @(
...)
.
disown
[ job ... ] ¶&|
&!
Remove the specified jobs from the job table; the shell will no longer report their status, and will not complain if you try to exit an interactive shell with them running or stopped. If no job is specified, disown the current job.
If the jobs are currently stopped and the AUTO_CONTINUE
option
is not set, a warning is printed containing information about how to
make them running after they have been disowned. If one of the latter
two forms is used, the jobs will automatically be made running,
independent of the setting of the AUTO_CONTINUE
option.
echo
[ -neE
] [ arg ... ] ¶Write each arg on the standard output, with a space separating
each one.
If the -n
flag is not present, print a newline at the end.
echo
recognizes the following escape sequences:
\a
bell character
\b
backspace
\c
suppress subsequent characters and final newline
\e
escape
\f
form feed
\n
linefeed (newline)
\r
carriage return
\t
horizontal tab
\v
vertical tab
\\
backslash
\0
NNNcharacter code in octal
\x
NNcharacter code in hexadecimal
\u
NNNNunicode character code in hexadecimal
\U
NNNNNNNNunicode character code in hexadecimal
The -E
flag, or the BSD_ECHO
option, can be used to disable
these escape sequences. In the latter case, -e
flag can be used to
enable them.
Note that for standards compliance a double dash does not terminate
option processing; instead, it is printed directly. However, a
single dash does terminate option processing, so the first dash,
possibly following options, is not printed, but everything following it
is printed as an argument. The single dash behaviour is different
from other shells. For a more portable way of printing text, see
printf
, and for a more controllable way of printing text within zsh,
see print
.
echotc
echoti
emulate
[ -lLR
] [ {zsh
|sh
|ksh
|csh
} [ flags ... ] ] ¶Without any argument print current emulation mode.
With single argument set up zsh options to emulate the specified shell
as much as possible.
csh will never be fully emulated.
If the argument is not one of the shells listed above, zsh
will be used as a default; more precisely, the tests performed on the
argument are the same as those used to determine the emulation at startup
based on the shell name, see
Compatibility
. In addition to setting shell options, the command also restores
the pristine state of pattern enables, as if all patterns had been
enabled using enable -p
.
If the emulate
command occurs inside a function that has been
marked for execution tracing with functions -t
then the xtrace
option will be turned on regardless of emulation mode or other options.
Note that code executed inside the function by the .
, source
, or
eval
commands is not considered to be running directly from the
function, hence does not provoke this behaviour.
If the -R
switch is given, all settable options
are reset to their default value corresponding to the specified emulation
mode, except for certain options describing the interactive
environment; otherwise, only those options likely to cause portability
problems in scripts and functions are altered. If the -L
switch is given,
the options LOCAL_OPTIONS
, LOCAL_PATTERNS
and LOCAL_TRAPS
will be set as
well, causing the effects of the emulate
command and any setopt
,
disable -p
or enable -p
, and trap
commands to be local to
the immediately surrounding shell
function, if any; normally these options are turned off in all emulation
modes except ksh
. The -L
switch is mutually exclusive with the
use of -c
in flags.
If there is a single argument and the -l
switch is given, the
options that would be set or unset (the latter indicated with the prefix
‘no
’) are listed. -l
can be combined with -L
or -R
and
the list will be modified in the appropriate way. Note the list does
not depend on the current setting of options, i.e. it includes all
options that may in principle change, not just those that would actually
change.
The flags may be any of the invocation-time flags described in
Invocation,
except that ‘-o EMACS
’ and ‘-o VI
’ may not be used. Flags such
as ‘+r
’/‘+o RESTRICTED
’ may be prohibited in some circumstances.
If -c
arg appears in flags, arg is evaluated while the
requested emulation is temporarily in effect. In this case the emulation
mode and all options are restored to their previous values before
emulate
returns. The -R
switch may precede the name of the shell
to emulate; note this has a meaning distinct from including -R
in
flags.
Use of -c
enables ‘sticky’ emulation mode for functions defined
within the evaluated expression: the emulation mode is associated
thereafter with the function so that whenever the function is executed
the emulation (respecting the -R
switch, if present) and all
options are set (and pattern disables cleared)
before entry to the function, and the state is restored after exit.
If the function is called when the sticky emulation is already in
effect, either within an ‘emulate
shell -c
’ expression or
within another function with the same sticky emulation, entry and exit
from the function do not cause options to be altered (except due to
standard processing such as the LOCAL_OPTIONS
option). This also
applies to functions marked for autoload within the sticky emulation;
the appropriate set of options will be applied at the point the
function is loaded as well as when it is run.
For example:
emulate sh -c 'fni() { setopt cshnullglob; } fno() { fni; }' fno
The two functions fni
and fno
are defined with sticky sh
emulation. fno
is then executed, causing options associated
with emulations to be set to their values in sh
. fno
then
calls fni
; because fni
is also marked for sticky sh
emulation, no option changes take place on entry to or exit from it.
Hence the option cshnullglob
, turned off by sh
emulation, will
be turned on within fni
and remain on return to fno
. On exit
from fno
, the emulation mode and all options will be restored to the
state they were in before entry to the temporary emulation.
The documentation above is typically sufficient for the intended purpose of executing code designed for other shells in a suitable environment. More detailed rules follow.
The sticky emulation environment provided by ‘emulate
shell -c
’ is identical to that provided by entry to
a function marked for sticky emulation as a consequence of being
defined in such an environment. Hence, for example, the sticky
emulation is inherited by subfunctions defined within functions
with sticky emulation.
No change of options takes place on entry to or exit from functions that are not marked for sticky emulation, other than those that would normally take place, even if those functions are called within sticky emulation.
No special handling is provided for functions marked for
autoload
nor for functions present in wordcode created by
the zcompile
command.
The presence or absence of the -R
switch to emulate
corresponds to different sticky emulation modes, so for example
‘emulate sh -c
’, ‘emulate -R sh -c
’ and ‘emulate csh -c
’
are treated as three distinct sticky emulations.
Difference in shell options supplied in addition to the
basic emulation also mean the sticky emulations are different, so for
example ‘emulate zsh -c
’ and ‘emulate zsh -o cbases -c
’ are
treated as distinct sticky emulations.
enable
[ -afmprs
] name ... ¶Enable the named hash table elements, presumably disabled
earlier with disable
. The default is to enable builtin commands.
The -a
option causes enable
to act on regular or global aliases.
The -s
option causes enable
to act on suffix aliases.
The -f
option causes enable
to act on shell functions. The -r
option causes enable
to act on reserved words. Without arguments
all enabled hash table elements from the corresponding hash table are
printed. With the -m
flag the arguments are taken as patterns
(should be quoted) and all hash table elements from the corresponding
hash table matching these patterns are enabled. Enabled objects can be
disabled with the disable
builtin command.
enable -p
reenables patterns disabled with disable -p
. Note
that it does not override globbing options; for example, ‘enable -p
"~"
’ does not cause the pattern character ~
to be active unless
the EXTENDED_GLOB
option is also set. To enable all possible
patterns (so that they may be individually disabled with disable -p
),
use ‘setopt EXTENDED_GLOB KSH_GLOB NO_SH_GLOB
’.
eval
[ arg ... ] ¶Read the arguments as input to the shell and execute the resulting command(s) in the current shell process. The return status is the same as if the commands had been executed directly by the shell; if there are no args or they contain no commands (i.e. are an empty string or whitespace) the return status is zero.
exec
[ -cl
] [ -a
argv0 ] [ command [ arg ... ] ]Replace the current shell with command rather than forking. If command is a shell builtin command or a shell function, the shell executes it, and exits when the command is complete.
With -c
clear the environment; with -l
prepend -
to the
argv[0]
string of the command executed (to simulate a login shell);
with -a
argv0 set the argv[0]
string of the command
executed.
See Precommand Modifiers.
If the option POSIX_BUILTINS
is set, command is never
interpreted as a shell builtin command or shell function. This
means further precommand modifiers such as builtin
and
noglob
are also not interpreted within the shell. Hence
command is always found by searching the command path.
If command is omitted but any redirections are specified, then the redirections will take effect in the current shell.
exit
[ n ] ¶Exit the shell with the exit status specified by an arithmetic
expression n; if none
is specified, use the exit status from the last command executed.
An EOF condition will also cause the shell to exit, unless
the IGNORE_EOF
option is set.
See notes at the end of
Jobs & Signals for some possibly unexpected interactions
of the exit
command with jobs.
export
[ name[=
value] ... ] ¶The specified names are marked for automatic export
to the environment of subsequently executed commands.
Equivalent to typeset -gx
.
If a parameter specified does not
already exist, it is created in the global scope.
false
[ arg ... ] ¶Do nothing and return an exit status of 1.
fc
[ -e
ename ] [ -s
] [ -LI
] [ -m
match ] [ old=
new ... ] [ first [ last ] ]fc -l
[ -LI
] [ -nrdfEiD
] [ -t
timefmt ] [ -m
match ]
[ old=
new ... ] [ first [ last ] ]fc -p
[ -a
] [ filename [ histsize [ savehistsize ] ] ]fc
-P
fc
-ARWI
[ filename ]The fc
command controls the interactive history mechanism. Note
that reading and writing of history options is only performed if the
shell is interactive. Usually this is detected automatically, but
it can be forced by setting the interactive
option when starting the
shell.
The first two forms of this command select a range of events from
first to last from the history list. The arguments first
and last may be specified as a number or as a string. A negative
number is used as an offset to the current history event number. A string
specifies the most recent event beginning with the given string. All
substitutions old=
new, if any, are then performed on the
text of the events.
The range of events selected by numbers can be narrowed further by the following flags.
-I
restricts to only internal events (not from $HISTFILE
)
-L
restricts to only local events (not from other shells, see
SHARE_HISTORY
in Description of Options – note that $HISTFILE
is
considered local when read at startup)
-m
takes the first argument as a pattern (which should be quoted) and only the history events matching this pattern are considered
If first is not specified, it will be set to -1 (the most recent
event), or to -16 if the -l
flag is given.
If last is not specified, it will be set to first,
or to -1 if the -l
flag is given.
However, if the current event has added entries to the history with
‘print -s
’ or ‘fc -R
’, then the default last for -l
includes all new history entries since the current event began.
When the -l
flag is given, the resulting events are listed on
standard output. Otherwise the editor program specified by -e
ename
is invoked on a file containing these history events. If -e
is not given, the
value of the parameter FCEDIT
is used; if that is not set the value of
the parameter EDITOR
is used; if that is not set a builtin default,
usually ‘vi
’ is used. If ename is ‘-
’, no editor is invoked.
When editing is complete, the edited command is executed.
The flag ‘-s
’ is equivalent to ‘-e -
’.
The flag -r
reverses the order of the events and the
flag -n
suppresses event numbers when listing.
Also when listing,
-d
prints timestamps for each event
-f
prints full time-date stamps in the US
‘MM/
DD/
YY hh:
mm’ format
-E
prints full time-date stamps in the European
‘dd.
mm.
yyyy hh:
mm’ format
-i
prints full time-date stamps in ISO8601
‘yyyy-
mm-
dd hh:
mm’ format
-t
fmtprints time and date stamps in the given format;
fmt is formatted with the strftime function with the zsh extensions
described for the %D{
string}
prompt format in
Prompt Expansion. The resulting formatted string must be
no more than 256 characters or will not be printed
-D
prints elapsed times; may be combined with one of the options above
‘fc -p
’ pushes the current history list onto a stack and switches to a
new history list. If the -a
option is also specified, this history list
will be automatically popped when the current function scope is exited, which
is a much better solution than creating a trap function to call ‘fc -P
’
manually. If no arguments are specified, the history list is left empty,
$HISTFILE
is unset, and $HISTSIZE
& $SAVEHIST
are set to their
default values. If one argument is given, $HISTFILE
is set to that
filename, $HISTSIZE
& $SAVEHIST
are left unchanged, and the history
file is read in (if it exists) to initialize the new list. If a second
argument is specified, $HISTSIZE
& $SAVEHIST
are instead set to the
single specified numeric value. Finally, if a third argument is specified,
$SAVEHIST
is set to a separate value from $HISTSIZE
. You are free to
change these environment values for the new history list however you desire
in order to manipulate the new history list.
‘fc -P
’ pops the history list back to an older list saved by ‘fc -p
’.
The current list is saved to its $HISTFILE
before it is destroyed
(assuming that $HISTFILE
and $SAVEHIST
are set appropriately, of
course). The values of $HISTFILE
, $HISTSIZE
, and $SAVEHIST
are
restored to the values they had when ‘fc -p
’ was called. Note that this
restoration can conflict with making these variables "local", so your best
bet is to avoid local declarations for these variables in functions that use
‘fc -p
’. The one other guaranteed-safe combination is declaring these
variables to be local at the top of your function and using the automatic
option (-a
) with ‘fc -p
’. Finally, note that it is legal to manually
pop a push marked for automatic popping if you need to do so before the
function exits.
‘fc -R
’ reads the history from the given file,
‘fc -W
’ writes the history out to the given file,
and ‘fc -A
’ appends the history out to the given file.
If no filename is specified, the $HISTFILE
is assumed.
If the -I
option is added to -R
, only those events that are
not already contained within the internal history list are added.
If the -I
option is added to -A
or -W
, only those
events that are new since last incremental append/write to
the history file are appended/written.
In any case, the created file will have no more than $SAVEHIST
entries.
fg
[ job ... ] ¶Bring each specified job in turn to the foreground. If no job is specified, resume the current job.
float
[ {+
|-
}Hghlprtux
] [ {+
|-
}EFLRZ
[ n ] ] [ name[=
value] ... ] ¶Equivalent to typeset -E
, except that options irrelevant to floating
point numbers are not permitted.
functions
[ {+
|-
}UkmtTuWz
] [ -x
num ] [ name ... ] ¶functions -c
oldfn newfnfunctions -M
[-s
] mathfn [ min [ max [ shellfn ] ] ]functions -M
[ -m
pattern ... ]functions +M
[ -m
] mathfn ...Equivalent to typeset -f
, with the exception of the -c
, -x
,
-M
and -W
options. For functions -u
and functions -U
,
see autoload
, which provides additional options. For functions -t
and functions -T
, see typeset -f
.
The -x
option indicates that any functions output will have
each leading tab for indentation, added by the shell to show syntactic
structure, expanded to the given number num of spaces. num
can also be 0 to suppress all indentation.
The -W
option turns on the option WARN_NESTED_VAR
for the named
function or functions only. The option is turned off at the start of
nested functions (apart from anonoymous functions) unless the called
function also has the -W
attribute.
The -c
option causes oldfn to be copied to newfn. The
copy is efficiently handled internally by reference counting. If
oldfn was marked for autoload it is first loaded and if this
fails the copy fails. Either function may subsequently be redefined
without affecting the other. A typical idiom is that oldfn is the
name of a library shell function which is then redefined to call
newfn
, thereby installing a modified version of the function.
Use of the -M
option may not be combined with any of the options
handled by typeset -f
.
functions -M
mathfn defines mathfn as the name of
a mathematical function recognised in all forms of arithmetical expressions;
see
Arithmetic Evaluation. By default mathfn may take
any number of comma-separated arguments. If min is given,
it must have exactly min args; if min and max are
both given, it must have at least min and at most max
args. max may be -1 to indicate that there is no upper limit.
By default the function is implemented by a shell function of the same
name; if shellfn is specified it gives the name of the corresponding
shell function while mathfn remains the name used in arithmetical
expressions. The name of the function in $0
is mathfn (not
shellfn as would usually be the case), provided the option
FUNCTION_ARGZERO
is in effect. The positional parameters in the shell
function correspond to the arguments of the mathematical function call.
The result of the last arithmetical expression evaluated inside the shell
function gives the result of the mathematical function. This is not limited to
arithmetic substitutions of the form $((
...))
,
but also includes arithmetical expressions evaluated in any other way, including
by the let
builtin,
by ((
...))
statements,
and even
by the return
builtin
and
by array subscripts.
Therefore, care must be taken not to use syntactical constructs that perform
arithmetic evaluation after evaluating what is to be the result of the function.
For example:
# WRONG zmath_cube() { (( $1 * $1 * $1 )) return 0 } functions -M cube 1 1 zmath_cube print $(( cube(3) ))
This will print ‘0
’ because of the return
.
Commenting the return
out would lead to a different problem: the
((
...))
statement would become
the last statement in the function, so the return status ($?
) of the
function would be non-zero (indicating failure) whenever the arithmetic
result of the function would happen to be zero (numerically):
# WRONG zmath_cube() { (( $1 * $1 * $1 )) } functions -M cube 1 1 zmath_cube print $(( cube(0) ))
Instead, the true
builtin can be used:
# RIGHT zmath_cube() { (( $1 * $1 * $1 )) true } functions -M cube 1 1 zmath_cube print $(( cube(3) ))
If the additional option -s
is given to functions -M
, the
argument to the function is a single string: anything between the
opening and matching closing parenthesis is passed to the function as a
single argument, even if it includes commas or white space. The minimum
and maximum argument specifiers must therefore be 1 if given. An empty
argument list is passed as a zero-length string.
Thus, the following string function takes a single argument, including
the commas, and prints 11:
stringfn() { (( $#1 )); true } functions -Ms stringfn print $(( stringfn(foo,bar,rod) ))
functions -M
with no arguments lists all such user-defined functions in
the same form as a definition. With the additional option -m
and
a list of arguments, all functions whose mathfn matches one of
the pattern arguments are listed.
function +M
removes the list of mathematical functions; with the
additional option -m
the arguments are treated as patterns and
all functions whose mathfn matches the pattern are removed. Note
that the shell function implementing the behaviour is not removed
(regardless of whether its name coincides with mathfn).
getcap
See The zsh/cap Module.
getln
[ -AclneE
] name ... ¶Read the top value from the buffer stack and put it in
the shell parameter name. Equivalent to
read -zr
.
getopts
optstring name [ arg ... ] ¶Checks the args for legal options. If the args are omitted,
use the positional parameters. A valid option argument
begins with a ‘+
’ or a ‘-
’. An argument not beginning with
a ‘+
’ or a ‘-
’, or the argument ‘-
-
’, ends the options.
Note that a single ‘-
’ is not considered a valid option argument.
optstring contains the letters that getopts
recognizes. If a letter is followed by a ‘:
’, that option
requires an argument. The options can be
separated from the argument by blanks.
Each time it is invoked, getopts
places the option letter it finds
in the shell parameter name, prepended with a ‘+
’ when
arg begins with a ‘+
’. The index of the next arg
is stored in OPTIND
. The option argument, if any,
is stored in OPTARG
.
The first option to be examined may be changed by explicitly assigning
to OPTIND
. OPTIND
has an initial value of 1
, and is
normally set to 1
upon entry to a shell function and restored
upon exit. (The POSIX_BUILTINS
option disables this, and also changes
the way the value is calculated to match other shells.) OPTARG
is not reset and retains its value from the most recent call to
getopts
. If either of OPTIND
or OPTARG
is explicitly
unset, it remains unset, and the index or option argument is not
stored. The option itself is still stored in name in this case.
A leading ‘:
’ in optstring causes getopts
to store the
letter of any invalid option in OPTARG
, and to set name to
‘?
’ for an unknown option and to ‘:
’ when a required argument is
missing. Otherwise, getopts
sets name to ‘?
’ and prints
an error message when an option is invalid. The exit status is
nonzero when there are no more options.
hash
[ -Ldfmrv
] [ name[=
value] ] ... ¶hash
can be used to directly modify the contents of the command
hash table, and the named directory hash table. Normally one would
modify these tables by modifying one’s PATH
(for the command hash table) or by creating appropriate shell parameters
(for the named directory hash table).
The choice of hash table to work on is determined by the -d
option;
without the option the command hash table is used, and with the option the
named directory hash table is used.
A command name starting with a /
is never hashed, whether by
explicit use of the hash
command or otherwise. Such a command
is always found by direct look up in the file system.
Given no arguments, and neither the -r
or -f
options,
the selected hash table will be listed in full.
The -r
option causes the selected hash table to be emptied.
It will be subsequently rebuilt in the normal fashion.
The -f
option causes the selected hash table to be fully
rebuilt immediately. For the command hash table this hashes
all the absolute directories in the PATH
,
and for the named directory hash table this adds all users’ home directories.
These two options cannot be used with any arguments.
The -m
option causes the arguments to be taken as patterns
(which should be quoted) and the elements of the hash table
matching those patterns are printed. This is the only way to display
a limited selection of hash table elements.
For each name with a corresponding value, put ‘name’ in
the selected hash table, associating it with the pathname ‘value’.
In the command hash table, this means that
whenever ‘name’ is used as a command argument, the shell will try
to execute the file given by ‘value’.
In the named directory hash table, this means
that ‘value’ may be referred to as ‘~
name’.
For each name with no
corresponding value, attempt to add name to the hash table,
checking what the appropriate value
is in the normal manner for
that hash table. If an appropriate value
can’t be found, then
the hash table will be unchanged.
The -v
option causes hash table entries to be listed as they are
added by explicit specification. If has no effect if used with -f
.
If the -L
flag is present, then each hash table entry is printed in
the form of a call to hash.
history
¶Same as fc -l
.
integer
[ {+
|-
}Hghlprtux
] [ {+
|-
}LRZi
[ n ] ] [ name[=
value] ... ] ¶Equivalent to typeset -i
, except that options irrelevant to
integers are not permitted.
jobs
[ -dlprs
] [ job ... ] ¶jobs -Z
stringLists information about each given job, or all jobs
if job is omitted. The -l
flag lists process
IDs, and the -p
flag lists process groups.
If the -r
flag is specified only running jobs will be listed
and if the -s
flag is given only stopped jobs are shown.
If the -d
flag is given, the directory from which the job was
started (which may not be the current directory of the job) will also
be shown.
The -Z
option replaces the shell’s argument and environment space with
the given string, truncated if necessary to fit. This will normally be
visible in ps
(ps(1)) listings. This feature is typically
used by daemons, to indicate their state.
Full job control is only available in the top-level interactive shell,
not in commands run in the left hand side of pipelines or within
the (
...)
construct. However, a snapshot
of the job state at that point is taken, so it is still possible
to use the jobs
builtin, or any parameter providing job information.
This gives information about the state of jobs at the point the subshell
was created. If background processes are created within the subshell,
then instead information about those processes is provided.
For example,
sleep 10 & # Job in background ( # Shell forks jobs # Shows information about "sleep 10 &" sleep 5 & # Process in background (no job control) jobs # Shows information about "sleep 5 &" )
kill
[ -s
signal_name | -n
signal_number | -
sig ] job ... ¶kill
-l
[ sig ... ]Sends either SIGTERM
or the specified signal to the given
jobs or processes.
Signals are given by number or by names, with or without the ‘SIG
’
prefix.
If the signal being sent is not ‘KILL
’ or ‘CONT
’, then the job
will be sent a ‘CONT
’ signal if it is stopped.
The argument job can be the process ID of a job
not in the job list.
In the second form, kill -l
, if sig is not
specified the signal names are listed. Otherwise, for each
sig that is a name, the corresponding signal number is
listed. For each sig that is a signal number or a number
representing the exit status of a process which was terminated or
stopped by a signal the name of the signal is printed.
On some systems, alternative signal names are allowed for a few signals.
Typical examples are SIGCHLD
and SIGCLD
or SIGPOLL
and
SIGIO
, assuming they correspond to the same signal number. kill
-l
will only list the preferred form, however kill -l
alt will
show if the alternative form corresponds to a signal number. For example,
under Linux kill -l IO
and kill -l POLL
both output 29, hence
kill -IO
and kill -POLL
have the same effect.
Many systems will allow process IDs to be negative to kill a process group or zero to kill the current process group.
let
arg ... ¶Evaluate each arg as an arithmetic expression. See Arithmetic Evaluation for a description of arithmetic expressions. The exit status is 0 if the value of the last expression is nonzero, 1 if it is zero, and 2 if an error occurred.
limit
[ -hs
] [ resource [ limit ] ] ... ¶Set or display resource limits. Unless the -s
flag is given,
the limit applies only the children of the shell. If -s
is
given without other arguments, the resource limits of the current
shell is set to the previously set resource limits of the children.
If limit is not specified, print the current limit placed
on resource, otherwise
set the limit to the specified value. If the -h
flag
is given, use hard limits instead of soft limits.
If no resource is given, print all limits.
When looping over multiple resources, the shell will abort immediately if it detects a badly formed argument. However, if it fails to set a limit for some other reason it will continue trying to set the remaining limits.
resource can be one of:
addressspace
Maximum amount of address space used.
aiomemorylocked
Maximum amount of memory locked in RAM for AIO operations.
aiooperations
Maximum number of AIO operations.
cachedthreads
Maximum number of cached threads.
coredumpsize
Maximum size of a core dump.
cputime
Maximum CPU seconds per process.
datasize
Maximum data size (including stack) for each process.
descriptors
Maximum value for a file descriptor.
filesize
Largest single file allowed.
kqueues
Maximum number of kqueues allocated.
maxproc
Maximum number of processes.
maxpthreads
Maximum number of threads per process.
memorylocked
Maximum amount of memory locked in RAM.
memoryuse
Maximum resident set size.
msgqueue
Maximum number of bytes in POSIX message queues.
posixlocks
Maximum number of POSIX locks per user.
pseudoterminals
Maximum number of pseudo-terminals.
resident
Maximum resident set size.
sigpending
Maximum number of pending signals.
sockbufsize
Maximum size of all socket buffers.
stacksize
Maximum stack size for each process.
swapsize
Maximum amount of swap used.
vmemorysize
Maximum amount of virtual memory.
Which of these resource limits are available depends on the system. resource can be abbreviated to any unambiguous prefix. It can also be an integer, which corresponds to the integer defined for the resource by the operating system.
If argument corresponds to a number which is out of the range of the
resources configured into the shell, the shell will try to read or write
the limit anyway, and will report an error if this fails. As the shell
does not store such resources internally, an attempt to set the limit will
fail unless the -s
option is present.
limit is a number, with an optional scaling factor, as follows:
h
hours
k
kilobytes (default)
m
megabytes or minutes
g
gigabytes
:
]ssminutes and seconds
The limit
command is not made available by default when the
shell starts in a mode emulating another shell. It can be made available
with the command ‘zmodload -F zsh/rlimits b:limit
’.
local
[ {+
|-
}AHUahlprtux
] [ {+
|-
}EFLRZi
[ n ] ] [ name[=
value] ... ] ¶Same as typeset
, except that the options -g
, and
-f
are not permitted. In this case the -x
option does not force
the use of -g
, i.e. exported variables will be local to functions.
logout
[ n ] ¶Same as exit
, except that it only works in a login shell.
noglob
simple commandSee Precommand Modifiers.
popd
[ -q
] [ {+
|-
}n ] ¶Remove an entry from the directory stack, and perform a cd
to
the new top directory. With no argument, the current top entry is
removed. An argument of the form ‘+
n’ identifies a stack
entry by counting from the left of the list shown by the dirs
command,
starting with zero. An argument of the form -
n counts from the right.
If the PUSHD_MINUS
option is set, the meanings of ‘+
’ and
‘-
’ in this context are swapped.
If the -q
(quiet) option is specified, the hook function chpwd
and the functions in the array $chpwd_functions
are not called,
and the new directory stack is not printed. This is useful for calls to
popd
that do not change the environment seen by an interactive user.
print
[ -abcDilmnNoOpPrsSz
] [ -u
n ] [ -f
format ] [ -C
cols ] ¶
[ -v
name ] [ -xX
tabstop ] [ -R
[ -en
]] [ arg ... ]With the ‘-f
’ option the arguments are printed as described by printf
.
With no flags or with the flag ‘-
’, the arguments are printed on
the standard output as described by echo
, with the following differences:
the escape sequence ‘\M-
x’ (or ‘\M
x’) metafies the character
x (sets the highest bit),
‘\C-
x’ (or ‘\C
x’) produces a control character
(‘\C-@
’ and ‘\C-?
’ give the characters NULL and delete),
a character code in octal is represented by ‘\
NNN’
(instead of ‘\0
NNN’),
and ‘\E
’ is a synonym for ‘\e
’.
Finally, if not in an escape
sequence, ‘\
’ escapes the following character and is not printed.
-a
Print arguments with the column incrementing first. Only useful with the
-c
and -C
options.
-b
Recognize all the escape sequences defined for the bindkey
command,
see
Zle Builtins.
-c
Print the arguments in columns. Unless -a
is also given, arguments are
printed with the row incrementing first.
-C
colsPrint the arguments in cols columns. Unless -a
is also given,
arguments are printed with the row incrementing first.
-D
Treat the arguments as paths, replacing directory prefixes with ~
expressions corresponding to directory names, as appropriate.
-i
If given together with -o
or -O
, sorting is performed
case-independently.
-l
Print the arguments separated by newlines instead of spaces. Note: if
the list of arguments is empty, print -l
will still output one empty
line. To print a possibly-empty list of arguments one per line, use
print -C1
, as in ‘print -rC1 -- "$list[@]"
’.
-m
Take the first argument as a pattern (should be quoted), and remove it from the argument list together with subsequent arguments that do not match this pattern.
-n
Do not add a newline to the output.
-N
Print the arguments separated and terminated by nulls. Again,
print -rNC1 -- "$list[@]"
is a canonical way to print an
arbitrary list as null-delimited records.
-o
Print the arguments sorted in ascending order.
-O
Print the arguments sorted in descending order.
-p
Print the arguments to the input of the coprocess.
-P
Perform prompt expansion (see
Prompt Expansion).
In combination with ‘-f
’,
prompt escape sequences are parsed only within interpolated arguments,
not within the format string.
-r
Ignore the escape conventions of echo
.
-R
Emulate the BSD echo
command, which does not process escape sequences
unless the -e
flag is given. The -n
flag suppresses the trailing
newline. Only the -e
and -n
flags are recognized after
-R
; all other arguments and options are printed.
-s
Place the results in the history list instead of on the standard output.
Each argument to the print
command is treated as a single word in the
history, regardless of its content.
-S
Place the results in the history list instead of on the standard output.
In this case only a single argument is allowed; it will be split into
words as if it were a full shell command line. The effect is
similar to reading the line from a history file with the
HIST_LEX_WORDS
option active.
-u
nPrint the arguments to file descriptor n.
-v
nameStore the printed arguments as the value of the parameter name.
-x
tab-stopExpand leading tabs on each line of output in the printed string
assuming a tab stop every tab-stop characters. This is appropriate
for formatting code that may be indented with tabs. Note that leading
tabs of any argument to print, not just the first, are expanded, even if
print
is using spaces to separate arguments (the column count
is maintained across arguments but may be incorrect on output
owing to previous unexpanded tabs).
The start of the output of each print command is assumed to be aligned
with a tab stop. Widths of multibyte characters are handled if the
option MULTIBYTE
is in effect. This option is ignored if other
formatting options are in effect, namely column alignment or
printf
style, or if output is to a special location such as shell
history or the command line editor.
-X
tab-stopThis is similar to -x
, except that all tabs in the printed string
are expanded. This is appropriate if tabs in the arguments are
being used to produce a table format.
-z
Push the arguments onto the editing buffer stack, separated by spaces.
If any of ‘-m
’, ‘-o
’ or ‘-O
’ are used in combination with
‘-f
’ and there are no arguments (after the removal process in the
case of ‘-m
’) then nothing is printed.
printf
[ -v
name ] format [ arg ... ] ¶Print the arguments according to the format specification. Formatting
rules are the same as used in C. The same escape sequences as for echo
are recognised in the format. All C conversion specifications ending in
one of csdiouxXeEfgGn
are handled. In addition to this, ‘%b
’ can be
used instead of ‘%s
’ to cause escape sequences in the argument to be
recognised and ‘%q
’ can be used to quote the argument in such a way
that allows it to be reused as shell input. With the numeric format
specifiers, if the corresponding argument starts with a quote character,
the numeric value of the following character is used as the number to
print; otherwise the argument is evaluated as an arithmetic expression. See
Arithmetic Evaluation
for a description of arithmetic
expressions. With ‘%n
’, the corresponding argument is taken as an
identifier which is created as an integer parameter.
Normally, conversion specifications are applied to each argument in order
but they can explicitly specify the nth argument is to be used by
replacing ‘%
’ by ‘%
n$
’ and ‘*
’ by ‘*
n$
’.
It is recommended that you do not mix references of this explicit style
with the normal style and the handling of such mixed styles may be subject
to future change.
If arguments remain unused after formatting, the format string is reused
until all arguments have been consumed. With the print
builtin, this
can be suppressed by using the -r
option. If more arguments are
required by the format than have been specified, the behaviour is as if
zero or an empty string had been specified as the argument.
The -v
option causes the output to be stored as the value of the
parameter name, instead of printed. If name is an array and
the format string is reused when consuming arguments then one
array element will be used for each use of the format string.
pushd
[ -qsLP
] [ arg ] ¶pushd
[ -qsLP
] old newpushd
[ -qsLP
] {+
|-
}nChange the current directory, and push the old current directory
onto the directory stack. In the first form, change the
current directory to arg.
If arg is not specified, change to the second directory
on the stack (that is, exchange the top two entries), or
change to $HOME
if the PUSHD_TO_HOME
option is set or if there is only one entry on the stack.
Otherwise, arg is interpreted as it would be by cd
.
The meaning of old and new in the second form is also
the same as for cd
.
The third form of pushd
changes directory by rotating the
directory list. An argument of the form ‘+
n’ identifies a stack
entry by counting from the left of the list shown by the dirs
command, starting with zero. An argument of the form ‘-
n’ counts
from the right. If the PUSHD_MINUS
option is set, the meanings
of ‘+
’ and ‘-
’ in this context are swapped.
If the -q
(quiet) option is specified, the hook function chpwd
and the functions in the array $chpwd_functions
are not called,
and the new directory stack is not printed. This is useful for calls to
pushd
that do not change the environment seen by an interactive user.
If the option -q
is not specified and the shell option PUSHD_SILENT
is not set, the directory stack will be printed after a pushd
is
performed.
The options -s
, -L
and -P
have the same meanings as for the
cd
builtin.
pushln
[ arg ... ] ¶Equivalent to print -nz
.
pwd
[ -rLP
] ¶Print the absolute pathname of the current working directory.
If the -r
or the -P
flag is specified, or the CHASE_LINKS
option is set and the -L
flag is not given, the printed path will not
contain symbolic links.
r
¶Same as fc -e -
.
read
[ -rszpqAclneE
] [ -t
[ num ] ] [ -k
[ num ] ] [ -d
delim ] ¶
[ -u
n ] [ [name][?
prompt] ] [ name ... ]Read one line and break it into fields using the characters
in $IFS
as separators, except as noted below.
The first field is assigned to the first name, the second field
to the second name, etc., with leftover
fields assigned to the last name.
If name is omitted then
REPLY
is used for scalars and reply
for arrays.
-r
Raw mode: a ‘\
’ at the end of a line does not signify line
continuation and backslashes in the line don’t quote the following
character and are not removed.
-s
Don’t echo back characters if reading from the terminal.
-q
Read only one character from the terminal and set name to
‘y
’ if this character was ‘y
’ or ‘Y
’ and to ‘n
’ otherwise.
With this flag set the return status is zero only if the character was
‘y
’ or ‘Y
’. This option may be used with a timeout (see -t
); if
the read times out, or encounters end of file, status 2 is returned. Input is
read from the terminal unless one of -u
or -p
is present. This option
may also be used within zle widgets.
-k
[ num ]Read only one (or num) characters. All are assigned to the first
name, without word splitting. This flag is ignored when -q
is
present. Input is read from the terminal unless one of -u
or -p
is present. This option may also be used within zle widgets.
Note that despite the mnemonic ‘key’ this option does read full
characters, which may consist of multiple bytes if the option
MULTIBYTE
is set.
-z
Read one entry from the editor buffer stack and assign it to the first
name, without word splitting. Text is pushed onto the stack with
‘print -z
’ or with push-line
from the line editor (see
Zsh Line Editor). This flag is ignored when the -k
or -q
flags are present.
-e
-E
The input read is printed (echoed) to the standard output. If the -e
flag is used, no input is assigned to the parameters.
-A
The first name is taken as the name of an array and all words are assigned to it.
-c
-l
These flags are allowed only if called inside a
function used for completion (specified with the -K
flag to
compctl
). If the -c
flag is given, the words of the
current command are read. If the -l
flag is given, the whole
line is assigned as a scalar. If both flags are present, -l
is used and -c
is ignored.
-n
Together with -c
, the number of the word the cursor is on is
read. With -l
, the index of the character the cursor is on is
read. Note that the command name is word number 1, not word 0,
and that when the cursor is at the end of the line, its character
index is the length of the line plus one.
-u
nInput is read from file descriptor n.
-p
Input is read from the coprocess.
-d
delimInput is terminated by the first character of delim instead of by newline.
-t
[ num ]Test if input is available before attempting to read. If num
is present, it must begin with a digit and will be evaluated
to give a number of seconds, which may be a floating point number;
in this case the read times out if input is not available within this
time. If num is not present, it is taken to be zero, so that
read
returns immediately if no input is available.
If no input is available, return status 1 and do not set any variables.
This option is not available when reading from the editor buffer with
-z
, when called from within completion with -c
or -l
, with
-q
which clears the input queue before reading, or within zle where
other mechanisms should be used to test for input.
Note that read does not attempt to alter the input processing mode. The
default mode is canonical input, in which an entire line is read at a time,
so usually ‘read -t
’ will not read anything until an entire line has
been typed. However, when reading from the terminal with -k
input is processed one key at a time; in this case, only availability of
the first character is tested, so that e.g. ‘read -t -k 2
’ can still
block on the second character. Use two instances of ‘read -t -k
’ if
this is not what is wanted.
If the first argument contains a ‘?
’, the remainder of this
word is used as a prompt on standard error when the shell
is interactive.
The value (exit status) of read
is 1 when an end-of-file is
encountered, or when -c
or -l
is present and the command is
not called from a compctl
function, or as described for -q
.
Otherwise the value is 0.
The behavior of some combinations of the -k
, -p
, -q
, -u
and -z
flags is undefined. Presently -q
cancels all the others,
-p
cancels -u
, -k
cancels -z
, and otherwise -z
cancels both -p
and -u
.
The -c
or -l
flags cancel any and all of -kpquz
.
readonly
¶Same as typeset -r
. With the POSIX_BUILTINS
option set, same
as typeset -gr
.
rehash
¶Same as hash -r
.
return
[ n ] ¶Causes a shell function or ‘.
’ script to return to
the invoking script with the return status specified by
an arithmetic expression n.
For example, the following prints ‘42
’:
() { integer foo=40; return "foo + 2" } echo $?
If n is omitted, the return status is that of the last command executed.
If return
was executed from a trap in a TRAP
NAL function,
the effect is different for zero and non-zero return status. With zero
status (or after an implicit return at the end of the trap), the shell
will return to whatever it was previously processing; with a non-zero
status, the shell will behave as interrupted except that the return
status of the trap is retained. Note that the numeric value of the signal
which caused the trap is passed as the first argument, so the statement
‘return "128+$1"
’ will return the same status as if the signal
had not been trapped.
sched
See The zsh/sched Module.
set
[ {+
|-
}options | {+
|-
}o
[ option_name ] ] ... [ {+
|-
}A
[ name ] ]
[ arg ... ]Set the options for the shell and/or set the positional parameters, or
declare and set an array. If the -s
option is given, it causes the
specified arguments to be sorted before assigning them to the positional
parameters (or to the array name if -A
is used). With +s
sort arguments in descending order. For the meaning of the other flags, see
Options. Flags may be specified by name using the -o
option. If no option
name is supplied with -o
, the current option states are printed: see
the description of setopt
below for more information on the format.
With +o
they are printed in a form that can be used as input
to the shell.
If the -A
flag is specified, name is set to an array containing
the given args; if no name is specified, all arrays are printed
together with their values.
If +A
is used and name is an array, the
given arguments will replace the initial elements of that array; if no
name is specified, all arrays are printed without their values.
The behaviour of arguments after -A
name or +A
name
depends on whether the option KSH_ARRAYS
is set. If it is not set, all
arguments following name are treated as values for the array,
regardless of their form. If the option is set, normal option processing
continues at that point; only regular arguments are treated as values for
the array. This means that
set -A array -x -- foo
sets array
to ‘-x -
- foo
’ if KSH_ARRAYS
is not set, but sets
the array to foo
and turns on the option ‘-x
’ if it is set.
If the -A
flag is not present, but there are arguments beyond the
options, the positional parameters are set. If the option list (if any)
is terminated by ‘-
-
’, and there are no further arguments, the
positional parameters will be unset.
If no arguments and no ‘-
-
’ are given, then the names and values of
all parameters are printed on the standard output. If the only argument is
‘+
’, the names of all parameters are printed.
For historical reasons, ‘set -
’ is treated as ‘set +xv
’
and ‘set -
args’ as ‘set +xv --
args’ when in
any other emulation mode than zsh’s native mode.
setcap
See The zsh/cap Module.
setopt
[ {+
|-
}options | {+
|-
}o
option_name ] [ -m
] [ name ... ] ¶Set the options for the shell. All options specified either with flags or by name are set.
If no arguments are supplied, the names of all options currently set are
printed. The form is chosen so as to minimize the differences from the
default options for the current emulation (the default emulation being
native zsh
, shown as <Z>
in
Description of Options).
Options that are on by default for the emulation are
shown with the prefix no
only if they are off, while other options are
shown without the prefix no
and only if they are on. In addition to
options changed from the default state by the user, any options activated
automatically by the shell (for example, SHIN_STDIN
or INTERACTIVE
)
will be shown in the list. The format is further modified by the option
KSH_OPTION_PRINT
, however the rationale for choosing options with
or without the no
prefix remains the same in this case.
If the -m
flag is given the arguments are taken as patterns
(which should be quoted to protect them from filename expansion), and all
options with names matching these patterns are set.
Note that a bad option name does not cause execution of subsequent shell
code to be aborted; this is behaviour is different from that of ‘set
-o
’. This is because set
is regarded as a special builtin by the
POSIX standard, but setopt
is not.
shift
[ -p
] [ n ] [ name ... ] ¶The positional parameters ${
n+1}
... are renamed
to $1
..., where n is an arithmetic expression that
defaults to 1.
If any names are given then the arrays with these names are
shifted instead of the positional parameters.
If the option -p
is given arguments are instead removed (popped)
from the end rather than the start of the array.
source
file [ arg ... ] ¶Same as ‘.
’, except that the current directory is always searched and
is always searched first, before directories in $path
.
stat
See The zsh/stat Module.
suspend
[ -f
] ¶Suspend the execution of the shell (send it a SIGTSTP
)
until it receives a SIGCONT
.
Unless the -f
option is given, this will refuse to suspend a login shell.
test
[ arg ... ] ¶[
[ arg ... ] ]
Like the system version of test
. Added for compatibility;
use conditional expressions instead (see Conditional Expressions).
The main differences between the conditional expression syntax and the
test
and [
builtins are: these commands are not handled
syntactically, so for example an empty variable expansion may cause an
argument to be omitted; syntax errors cause status 2 to be returned instead
of a shell error; and arithmetic operators expect integer arguments rather
than arithmetic expressions.
The command attempts to implement POSIX and its extensions where these
are specified. Unfortunately there are intrinsic ambiguities in
the syntax; in particular there is no distinction between test operators
and strings that resemble them. The standard attempts to resolve these
for small numbers of arguments (up to four); for five or more arguments
compatibility cannot be relied on. Users are urged wherever possible to
use the ‘[[
’ test syntax which does not have these ambiguities.
times
¶Print the accumulated user and system times for the shell and for processes run from the shell.
trap
[ arg ] [ sig ... ] ¶arg is a series of commands (usually quoted to protect it from
immediate evaluation by the shell) to be read and executed when the shell
receives any of the signals specified by one or more sig args.
Each sig can be given as a number,
or as the name of a signal either with or without the string SIG
in front (e.g. 1, HUP, and SIGHUP are all the same signal).
If arg is ‘-
’, then the specified signals are reset to their
defaults, or, if no sig args are present, all traps are reset.
If arg is an empty string, then the specified signals are ignored by the shell (and by the commands it invokes).
If arg is omitted but one or more sig args are provided (i.e.
the first argument is a valid signal number or name), the effect is the
same as if arg had been specified as ‘-
’.
The trap
command with no arguments prints a list of commands
associated with each signal.
If sig is ZERR
then arg will be executed
after each command with a nonzero exit status. ERR
is an alias
for ZERR
on systems that have no SIGERR
signal (this is the
usual case).
If sig is DEBUG
then arg will be executed
before each command if the option DEBUG_BEFORE_CMD
is set
(as it is by default), else after each command. Here, a ‘command’ is
what is described as a ‘sublist’ in the shell grammar, see
Simple Commands & Pipelines.
If DEBUG_BEFORE_CMD
is set various additional features are available.
First, it is possible to skip the next command by setting the option
ERR_EXIT
; see the description of the ERR_EXIT
option in
Description of Options. Also, the shell parameter
ZSH_DEBUG_CMD
is set to the string corresponding to the command
to be executed following the trap. Note that this string is reconstructed
from the internal format and may not be formatted the same way as the
original text. The parameter is unset after the trap is executed.
If sig is 0
or EXIT
and the trap
statement is executed inside the body of a function,
then the command arg is executed after the function completes.
The value of $?
at the start of execution is the exit status of the
shell or the return status of the function exiting.
If sig is 0
or EXIT
and the trap
statement is not executed inside the body of a function,
then the command arg is executed when the shell terminates; the
trap runs before any zshexit
hook functions.
ZERR
, DEBUG
, and EXIT
traps are not executed inside other
traps. ZERR
and DEBUG
traps are kept within subshells, while
other traps are reset.
Note that traps defined with the trap
builtin are slightly different
from those defined as ‘TRAP
NAL () { ... }’, as the latter have
their own function environment (line numbers, local variables, etc.) while
the former use the environment of the command in which they were called.
For example,
trap 'print $LINENO' DEBUG
will print the line number of a command executed after it has run, while
TRAPDEBUG() { print $LINENO; }
will always print the number zero.
Alternative signal names are allowed as described under kill
above.
Defining a trap under either name causes any trap under an alternative
name to be removed. However, it is recommended that for consistency
users stick exclusively to one name or another.
true
[ arg ... ] ¶Do nothing and return an exit status of 0.
ttyctl
[ -fu
] ¶The -f
option freezes the tty (i.e. terminal or terminal emulator), and
-u
unfreezes it.
When the tty is frozen, no changes made to the tty settings by
external programs will be honored by the shell, except for changes in the
size of the screen; the shell will
simply reset the settings to their previous values as soon as each
command exits or is suspended. Thus, stty
and similar programs have
no effect when the tty is frozen. Freezing the tty does not cause
the current state to be remembered: instead, it causes future changes
to the state to be blocked.
Without options it reports whether the terminal is frozen or not.
Note that, regardless of whether the tty is frozen or not, the
shell needs to change the settings when the line editor starts, so
unfreezing the tty does not guarantee settings made on the
command line are preserved. Strings of commands run between
editing the command line will see a consistent tty state.
See also the shell variable STTY
for a means of initialising
the tty before running external commands and/or freezing the tty
around a single command.
type
[ -wfpamsS
] name ... ¶Equivalent to whence -v
.
typeset
[ {+
|-
}AHUaghlmrtux
] [ {+
|-
}EFLRZip
[ n ] ]
[ +
] [ name[=
value] ... ]typeset
-T
[ {+
|-
}Uglrux
] [ {+
|-
}LRZp
[ n ] ]
[ +
| SCALAR[=
value] array[=(
value ...)
] [ sep ] ]typeset
-f
[ {+
|-
}TUkmtuz
] [ +
] [ name ... ]Set or display attributes and values for shell parameters.
Except as noted below for control flags that change the behavior, a parameter is created for each name that does not already refer to one. When inside a function, a new parameter is created for every name (even those that already exist), and is unset again when the function completes. See Local Parameters. The same rules apply to special shell parameters, which retain their special attributes when made local.
For each name=
value assignment, the parameter
name is set to value. If the assignment is omitted and name
does not refer to an existing parameter, a new parameter is intialized
to empty string, zero, or empty array (as appropriate), unless the
shell option TYPESET_TO_UNSET
is set. When that option is set,
the parameter attributes are recorded but the parameter remains unset.
If the shell option TYPESET_SILENT
is not set, for each remaining
name that refers to a parameter that is already set, the name and
value of the parameter are printed in the form of an assignment.
Nothing is printed for newly-created parameters, or when any attribute
flags listed below are given along with the name. Using
‘+
’ instead of minus to introduce an attribute turns it off.
If no name is present, the names and values of all parameters are
printed. In this case the attribute flags restrict the display to only
those parameters that have the specified attributes, and using ‘+
’
rather than ‘-
’ to introduce the flag suppresses printing of the values
of parameters when there is no parameter name.
All forms of the command handle scalar assignment. Array assignment is
possible if any of the reserved words declare
, export
, float
,
integer
, local
, readonly
or typeset
is matched when the
line is parsed (N.B. not when it is executed). In this case the arguments
are parsed as assignments, except that the ‘+=
’ syntax and the
GLOB_ASSIGN
option are not supported, and scalar values after =
are not split further into words, even if expanded (regardless of the
setting of the KSH_TYPESET
option; this option is obsolete).
Examples of the differences between command and reserved word parsing:
# Reserved word parsing typeset svar=$(echo one word) avar=(several words)
The above creates a scalar parameter svar
and an array
parameter avar
as if the assignments had been
svar="one word" avar=(several words)
On the other hand:
# Normal builtin interface builtin typeset svar=$(echo two words)
The builtin
keyword causes the above to use the standard builtin
interface to typeset
in which argument parsing is performed in the same
way as for other commands. This example creates a scalar svar
containing the value two
and another scalar parameter words
with
no value. An array value in this case would either cause an error or be
treated as an obscure set of glob qualifiers.
Arbitrary arguments are allowed if they take the form of assignments after command line expansion; however, these only perform scalar assignment:
var='svar=val' typeset $var
The above sets the scalar parameter svar
to the value val
.
Parentheses around the value within var
would not cause array
assignment as they will be treated as ordinary characters when $var
is substituted. Any non-trivial expansion in the name part of the
assignment causes the argument to be treated in this fashion:
typeset {var1,var2,var3}=name
The above syntax is valid, and has the expected effect of setting the
three parameters to the same value, but the command line is parsed as
a set of three normal command line arguments to typeset
after
expansion. Hence it is not possible to assign to multiple arrays by
this means.
Note that each interface to any of the commands may be disabled
separately. For example, ‘disable -r typeset
’ disables the reserved
word interface to typeset
, exposing the builtin interface, while
‘disable typeset
’ disables the builtin. Note that disabling the
reserved word interface for typeset
may cause problems with the
output of ‘typeset -p
’, which assumes the reserved word interface is
available in order to restore array and associative array values.
Unlike parameter assignment statements, typeset
’s exit status on an
assignment that involves a command substitution does not reflect the exit
status of the command substitution. Therefore, to test for an error in
a command substitution, separate the declaration of the parameter from its
initialization:
# WRONG typeset var1=$(exit 1) || echo "Trouble with var1" # RIGHT typeset var1 && var1=$(exit 1) || echo "Trouble with var1"
To initialize a parameter param to a command output and mark it readonly,
use typeset -r
param or readonly
param after the parameter
assignment statement.
If no attribute flags are given, and either no name arguments are
present or the flag +m
is used, then each parameter name printed is
preceded by a list of the attributes of that parameter (array
,
association
, exported
, float
, integer
, readonly
,
or undefined
for autoloaded parameters not yet loaded). If +m
is
used with attribute flags, and all those flags are introduced with
+
, the matching parameter names are printed but their values
are not.
The following control flags change the behavior of typeset
:
+
If ‘+
’ appears by itself in a separate word as the last option,
then the names of all parameters (functions with -f
) are printed, but
the values (function bodies) are not. No name arguments may appear,
and it is an error for any other options to follow ‘+
’. The
effect of ‘+
’ is as if all attribute flags which precede it were
given with a ‘+
’ prefix. For example, ‘typeset -U +
’ is
equivalent to ‘typeset +U
’ and displays the names of all arrays having
the uniqueness attribute, whereas ‘typeset -f -U +
’ displays the
names of all autoloadable functions. If +
is the only option,
then type information (array, readonly, etc.) is also printed for each
parameter, in the same manner as ‘typeset +m "*"
’.
-g
The -g
(global) means that any resulting parameter will not be
restricted to local scope. Note that this does not necessarily mean that
the parameter will be global, as the flag will apply to any existing
parameter (even if unset) from an enclosing function. This flag does not
affect the parameter after creation, hence it has no effect when listing
existing parameters, nor does the flag +g
have any effect except in
combination with -m
(see below).
-m
If the -m
flag is given the name arguments are taken as patterns
(use quoting to prevent these from being interpreted as file patterns).
With no attribute flags, all parameters (or functions with the -f
flag) with matching names are printed (the shell option TYPESET_SILENT
is not used in this case).
If the +g
flag is combined with -m
, a new local parameter is
created for every matching parameter that is not already local. Otherwise
-m
applies all other flags or assignments to the existing parameters.
Except when assignments are made with name=
value, using
+m
forces the matching parameters and their attributes to be printed,
even inside a function. Note that -m
is ignored if no patterns are
given, so ‘typeset -m
’ displays attributes but ‘typeset -a +m
’
does not.
-p
[ n ]If the -p
option is given, parameters and values are printed in the
form of a typeset command with an assignment, regardless of other flags
and options. Note that the -H
flag on parameters is respected; no
value will be shown for these parameters.
-p
may be followed by an optional integer argument. Currently
only the value 1
is supported. In this case arrays and associative
arrays are printed with newlines between indented elements for
readability.
-T
[ scalar[=
value] array[=(
value ...)
] [ sep ] ]This flag has a different meaning when used with -f
; see below.
Otherwise the -T
option requires zero, two, or three arguments to be
present. With no arguments, the list of parameters created in this
fashion is shown. With two or three arguments, the first two are the name
of a scalar and of an array parameter (in that order) that will be tied
together in the manner of $PATH
and $path
. The optional third
argument is a single-character separator which will be used to join the
elements of the array to form the scalar; if absent, a colon is used, as
with $PATH
. Only the first character of the separator is significant;
any remaining characters are ignored. Multibyte characters are not
yet supported.
Only one of the scalar and array parameters may be assigned an initial value (the restrictions on assignment forms described above also apply).
Both the scalar and the array may be manipulated as normal. If one is
unset, the other will automatically be unset too. There is no way of
untying the variables without unsetting them, nor of converting the type
of one of them with another typeset
command; +T
does not work,
assigning an array to scalar is an error, and assigning a scalar to
array sets it to be a single-element array.
Note that both ‘typeset -xT ...
’ and ‘export -T ...
’ work, but
only the scalar will be marked for export. Setting the value using the
scalar version causes a split on all separators (which cannot be quoted).
It is possible to apply -T
to two previously tied variables but with a
different separator character, in which case the variables remain joined
as before but the separator is changed.
When an existing scalar is tied to a new array, the value of the scalar is preserved but no attribute other than export will be preserved.
Attribute flags that transform the final value (-L
, -R
, -Z
,
-l
, -u
) are only applied to the expanded value at the point
of a parameter expansion expression using ‘$
’. They are not applied
when a parameter is retrieved internally by the shell for any purpose.
The following attribute flags may be specified:
-A
The names refer to associative array parameters; see Array Parameters.
-L
[ n ]Left justify and remove leading blanks from the value when the parameter is expanded. If n is nonzero, it defines the width of the field. If n is zero, the width is determined by the width of the value of the first assignment. In the case of numeric parameters, the length of the complete value assigned to the parameter is used to determine the width, not the value that would be output.
The width is the count of characters, which may be multibyte characters
if the MULTIBYTE
option is in effect. Note that the screen
width of the character is not taken into account; if this is required,
use padding with parameter expansion flags
${(ml
...)
...}
as described in
‘Parameter Expansion Flags’ in
Parameter Expansion.
When the parameter is expanded, it is filled on the right with
blanks or truncated if necessary to fit the field.
Note truncation can lead to unexpected results with numeric parameters.
Leading zeros are removed if the -Z
flag is also set.
-R
[ n ]Similar to -L
, except that right justification is used;
when the parameter is expanded, the field is left filled with
blanks or truncated from the end. May not be combined with the -Z
flag.
-U
For arrays (but not for associative arrays), keep only the first
occurrence of each duplicated value. This may also be set for tied
parameters (see -T
) or colon-separated special parameters like
PATH
or FIGNORE
, etc. Note the flag takes effect on assignment,
and the type of the variable being assigned to is determinative; for
variables with shared values it is therefore recommended to set the flag
for all interfaces, e.g. ‘typeset -U PATH path
’.
This flag has a different meaning when used with -f
; see below.
-Z
[ n ]Specially handled if set along with the -L
flag.
Otherwise, similar to -R
, except that leading zeros are used for
padding instead of blanks if the first non-blank character is a digit.
Numeric parameters are specially handled: they are always eligible
for padding with zeroes, and the zeroes are inserted at an appropriate
place in the output.
-a
The names refer to array parameters. An array parameter may be
created this way, but it may be assigned to in the typeset
statement only if the reserved word form of typeset
is enabled
(as it is by default). When displaying, both normal and associative
arrays are shown.
-f
The names refer to functions rather than parameters. No assignments
can be made, and the only other valid flags are -t
, -T
, -k
,
-u
, -U
and -z
. The flag -t
turns on execution tracing
for this function; the flag -T
does the same, but turns off tracing
for any named (not anonymous) function called from the present one,
unless that function also
has the -t
or -T
flag. The -u
and -U
flags cause the
function to be marked for autoloading; -U
also causes alias
expansion to be suppressed when the function is loaded. See the
description of the ‘autoload
’ builtin for details.
Note that the builtin functions
provides the same basic capabilities
as typeset -f
but gives access to a few extra options; autoload
gives further additional options for the case typeset -fu
and
typeset -fU
.
-h
Hide: only useful for special parameters (those marked ‘<S>’ in the table in
Parameters Set By The Shell), and for local parameters with the same name as a special parameter,
though harmless for others. A special parameter with this attribute will
not retain its special effect when made local. Thus after ‘typeset -h
PATH
’, a function containing ‘typeset PATH
’ will create an ordinary
local parameter without the usual behaviour of PATH
. Alternatively,
the local parameter may itself be given this attribute; hence inside a
function ‘typeset -h PATH
’ creates an ordinary local parameter and the
special PATH
parameter is not altered in any way. It is also possible
to create a local parameter using ‘typeset +h
special’, where the
local copy of special will retain its special properties regardless of
having the -h
attribute. Global special parameters loaded from shell
modules (currently those in zsh/mapfile
and zsh/parameter
) are
automatically given the -h
attribute to avoid name clashes.
-H
Hide value: specifies that typeset
will not display the value of the
parameter when listing parameters; the display for such parameters is
always as if the ‘+
’ flag had been given. Use of the parameter is
in other respects normal, and the option does not apply if the parameter is
specified by name, or by pattern with the -m
option. This is on by
default for the parameters in the zsh/parameter
and zsh/mapfile
modules. Note, however, that unlike the -h
flag this is also useful
for non-special parameters.
-i
[ n ]Use an internal integer representation. If n is nonzero it defines the output arithmetic base, otherwise it is determined by the first assignment. Bases from 2 to 36 inclusive are allowed.
-E
[ n ]Use an internal double-precision floating point representation. On output the variable will be converted to scientific notation. If n is nonzero it defines the number of significant figures to display; the default is ten.
-F
[ n ]Use an internal double-precision floating point representation. On output the variable will be converted to fixed-point decimal notation. If n is nonzero it defines the number of digits to display after the decimal point; the default is ten.
-l
Convert the result to lower case whenever the parameter is expanded. The value is not converted when assigned.
-r
The given names are marked readonly. Note that if name is a special parameter, the readonly attribute can be turned on, but cannot then be turned off.
If the POSIX_BUILTINS
option is set, the readonly attribute is
more restrictive: unset variables can be marked readonly and cannot then
be set; furthermore, the readonly attribute cannot be removed from any
variable.
It is still possible to change other attributes of the variable though,
some of which like -U
or -Z
would affect the value. More generally,
the readonly attribute should not be relied on as a security mechanism.
Note that in zsh (like in pdksh but unlike most other shells) it is still possible to create a local variable of the same name as this is considered a different variable (though this variable, too, can be marked readonly). Special variables that have been made readonly retain their value and readonly attribute when made local.
-t
Tags the named parameters. Tags have no special meaning to the shell.
This flag has a different meaning when used with -f
; see above.
-u
Convert the result to upper case whenever the parameter is expanded.
The value is not converted when assigned.
This flag has a different meaning when used with -f
; see above.
-x
Mark for automatic export to the environment of subsequently
executed commands. If the option GLOBAL_EXPORT
is set, this implies
the option -g
, unless +g
is also explicitly given; in other words
the parameter is not made local to the enclosing function. This is for
compatibility with previous versions of zsh.
ulimit
[ -HSa
] [ { -bcdfiklmnpqrsTtvwx
| -N
resource } [ limit ] ... ] ¶Set or display resource limits of the shell and the processes started by
the shell. The value of limit can be a number in the unit specified
below or one of the values ‘unlimited
’, which removes the limit on the
resource, or ‘hard
’, which uses the current value of the hard limit on
the resource.
By default, only soft limits are manipulated. If the -H
flag
is given use hard limits instead of soft limits. If the -S
flag is given
together with the -H
flag set both hard and soft limits.
If no options are used, the file size limit (-f
) is assumed.
If limit is omitted the current value of the specified resources are printed. When more than one resource value is printed, the limit name and unit is printed before each value.
When looping over multiple resources, the shell will abort immediately if it detects a badly formed argument. However, if it fails to set a limit for some other reason it will continue trying to set the remaining limits.
Not all the following resources are supported on all systems. Running
ulimit -a
will show which are supported.
-a
Lists all of the current resource limits.
-b
Socket buffer size in bytes (N.B. not kilobytes)
-c
512-byte blocks on the size of core dumps.
-d
Kilobytes on the size of the data segment.
-f
512-byte blocks on the size of files written.
-i
The number of pending signals.
-k
The number of kqueues allocated.
-l
Kilobytes on the size of locked-in memory.
-m
Kilobytes on the size of physical memory.
-n
open file descriptors.
-p
The number of pseudo-terminals.
-q
Bytes in POSIX message queues.
-r
Maximum real time priority. On some systems where this
is not available, such as NetBSD, this has the same effect as -T
for compatibility with sh
.
-s
Kilobytes on the size of the stack.
-T
The number of simultaneous threads available to the user.
-t
CPU seconds to be used.
-u
The number of processes available to the user.
-v
Kilobytes on the size of virtual memory. On some systems this refers to the limit called ‘address space’.
-w
Kilobytes on the size of swapped out memory.
-x
The number of locks on files.
A resource may also be specified by integer in the form ‘-N
resource’, where resource corresponds to the integer defined for
the resource by the operating system. This may be used to set the limits
for resources known to the shell which do not correspond to option letters.
Such limits will be shown by number in the output of ‘ulimit -a
’.
The number may alternatively be out of the range of limits compiled into the shell. The shell will try to read or write the limit anyway, and will report an error if this fails.
umask
[ -S
] [ mask ] ¶The umask is set to mask. mask can be either
an octal number or a symbolic value as described in the chmod(1) man page.
If mask is omitted, the current value is printed. The -S
option causes the mask to be printed as a symbolic value. Otherwise,
the mask is printed as an octal number. Note that in
the symbolic form the permissions you specify are those which are to be
allowed (not denied) to the users specified.
unalias
[ -ams
] name ... ¶Removes aliases. This command works the same as unhash -a
, except that
the -a
option removes all regular or global aliases, or with -s
all suffix aliases: in this case no name arguments may appear. The
options -m
(remove by pattern) and -s
without -a
(remove
listed suffix aliases) behave as for unhash -a
. Note that
the meaning of -a
is different between unalias
and unhash
.
unfunction
¶Same as unhash -f
.
unhash
[ -adfms
] name ... ¶Remove the element named name from an internal hash table. The
default is remove elements from the command hash table. The -a
option causes unhash
to remove regular or global aliases; note
when removing a global aliases that the argument must be quoted to prevent
it from being expanded before being passed to the command.
The -s
option causes unhash
to remove suffix aliases.
The -f
option causes
unhash
to remove shell functions. The -d
options causes
unhash
to remove named directories. If the -m
flag is given
the arguments are taken as patterns (should be quoted) and all elements
of the corresponding hash table with matching names will be removed.
unlimit
[ -hs
] resource ... ¶The resource limit for each resource is set to the hard limit.
If the -h
flag is given and the shell has appropriate privileges,
the hard resource limit for each resource is removed.
The resources of the shell process are only changed if the -s
flag is given.
The unlimit
command is not made available by default when the
shell starts in a mode emulating another shell. It can be made available
with the command ‘zmodload -F zsh/rlimits b:unlimit
’.
unset
[ -fmv
] name ... ¶Each named parameter is unset. Local parameters remain local even if unset; they appear unset within scope, but the previous value will still reappear when the scope ends.
Individual elements of associative array parameters may be unset by using
subscript syntax on name, which should be quoted (or the entire command
prefixed with noglob
) to protect the subscript from filename generation.
If the -m
flag is specified the arguments are taken as patterns (should
be quoted) and all parameters with matching names are unset. Note that this
cannot be used when unsetting associative array elements, as the subscript
will be treated as part of the pattern.
The -v
flag specifies that name refers to parameters. This is the
default behaviour.
unset -f
is equivalent to unfunction
.
unsetopt
[ {+
|-
}options | {+
|-
}o
option_name ] [ name ... ] ¶Unset the options for the shell. All options specified either
with flags or by name are unset. If no arguments are supplied,
the names of all options currently unset are printed.
If the -m
flag is given the arguments are taken as patterns
(which should be quoted to preserve them from being interpreted as glob
patterns), and all options with names matching these patterns are unset.
vared
See Zle Builtins.
wait
[ job ... ] ¶Wait for the specified jobs or processes. If job is not given
then all currently active child processes are waited for.
Each job can be either a job specification or the process ID
of a job in the job table.
The exit status from this command is that of the job waited for.
If job represents an unknown job or process ID, a warning is printed
(unless the POSIX_BUILTINS
option is set) and the exit status is 127.
It is possible to wait for recent processes (specified by process ID,
not by job) that were running in the background even if the process has
exited. Typically the process ID will be recorded by capturing the
value of the variable $!
immediately after the process has been
started. There is a limit on the number of process IDs remembered by
the shell; this is given by the value of the system configuration
parameter CHILD_MAX
. When this limit is reached, older process IDs
are discarded, least recently started processes first.
Note there is no protection against the process ID wrapping, i.e. if the wait is not executed soon enough there is a chance the process waited for is the wrong one. A conflict implies both process IDs have been generated by the shell, as other processes are not recorded, and that the user is potentially interested in both, so this problem is intrinsic to process IDs.
whence
[ -vcwfpamsS
] [ -x
num ] name ... ¶For each name, indicate how it would be interpreted if used as a command name.
If name is not an alias, built-in command, external command, shell
function, hashed command, or a reserved word, the exit status shall be
non-zero, and — if -v
, -c
, or -w
was passed — a message
will be written to standard output. (This is different from other shells that
write that message to standard error.)
whence
is most useful when name is only the last path component
of a command, i.e. does not include a ‘/
’; in particular, pattern
matching only succeeds if just the non-directory component of the command is
passed.
-v
Produce a more verbose report.
-c
Print the results in a csh-like format.
This takes precedence over -v
.
-w
For each name, print ‘name:
word’ where word
is one of alias
, builtin
, command
, function
,
hashed
, reserved
or none
, according as name
corresponds to an alias, a built-in command, an external command, a
shell function, a command defined with the hash
builtin, a
reserved word, or is not recognised. This takes precedence over
-v
and -c
.
-f
Causes the contents of a shell function to be
displayed, which would otherwise not happen unless the -c
flag were used.
-p
Do a path search for name even if it is an alias, reserved word, shell function or builtin.
-a
Do a search for all occurrences of name throughout the command path. Normally only the first occurrence is printed.
-m
The arguments are taken as patterns (pattern characters should be quoted), and the information is displayed for each command matching one of these patterns.
-s
If a pathname contains symlinks, print the symlink-free pathname as well.
-S
As -s
, but if the pathname had to be resolved by following
multiple symlinks, the intermediate steps are printed, too. The
symlink resolved at each step might be anywhere in the path.
-x
numExpand tabs when outputting shell functions using the -c
option.
This has the same effect as the -x
option to the functions
builtin.
where
[ -wpmsS
] [ -x
num ] name ... ¶Equivalent to whence -ca
.
which
[ -wpamsS
] [ -x
num ] name ... ¶Equivalent to whence -c
.
zcompile
[ -U
] [ -z
| -k
] [ -R
| -M
] file [ name ... ] ¶zcompile
-ca
[ -m
] [ -R
| -M
] file [ name ... ]zcompile -t
file [ name ... ]This builtin command can be used to compile functions or scripts, storing the compiled form in a file, and to examine files containing the compiled form. This allows faster autoloading of functions and sourcing of scripts by avoiding parsing of the text when the files are read.
The first form (without the -c
, -a
or -t
options) creates a
compiled file. If only the file argument is given, the
output file has the name ‘file.zwc
’ and will be placed in
the same directory as the file. The shell will load the compiled
file instead of the normal function file when the function
is autoloaded; see
Functions
for a description of how autoloaded functions are searched. The
extension .zwc
stands for ‘zsh word code’.
If there is at least one name argument, all the named files
are compiled into the output file given as the first argument. If
file does not end in .zwc
, this extension is automatically
appended. Files containing multiple compiled functions are called ‘digest’
files, and are intended to be used as elements of the FPATH
/fpath
special array.
The second form, with the -c
or -a
options, writes the compiled
definitions for all the named functions into file. For -c
, the
names must be functions currently defined in the shell, not those marked
for autoloading. Undefined functions that are marked for autoloading
may be written by using the -a
option, in which case the fpath
is searched and the contents of the definition files for those
functions, if found, are compiled into file. If both -c
and
-a
are given, names of both defined functions and functions marked
for autoloading may be given. In either case, the functions in files
written with the -c
or -a
option will be autoloaded as if the
KSH_AUTOLOAD
option were unset.
The reason for handling loaded and not-yet-loaded functions with
different options is that some definition files for autoloading define
multiple functions, including the function with the same name as the
file, and, at the end, call that function. In such cases the output of
‘zcompile -c
’ does not include the additional functions defined in
the file, and any other initialization code in the file is lost. Using
‘zcompile -a
’ captures all this extra information.
If the -m
option is combined with -c
or -a
,
the names are used as patterns and all functions whose names
match one of these patterns will be written. If no name is given,
the definitions of all functions currently defined or marked as
autoloaded will be written.
Note the second form cannot be used for compiling functions that include redirections as part of the definition rather than within the body of the function; for example
fn1() { { ... } >~/logfile }
can be compiled but
fn1() { ... } >~/logfile
cannot. It is possible to use the first form of zcompile
to compile
autoloadable functions that include the full function definition instead
of just the body of the function.
The third form, with the -t
option, examines an existing
compiled file. Without further arguments, the names of the original
files compiled into it are listed. The first line of output shows
the version of the shell which compiled the file and how the file
will be used (i.e. by reading it directly or by mapping it into memory).
With arguments, nothing is output and the return status is set to zero if
definitions for all names were found in the compiled
file, and non-zero if the definition for at least one name was not
found.
Other options:
-U
Aliases are not expanded when compiling the named files.
-R
When the compiled file is read, its contents are copied into the
shell’s memory, rather than memory-mapped (see -M
). This
happens automatically on systems that do not support memory mapping.
When compiling scripts instead of autoloadable functions, it is often desirable to use this option; otherwise the whole file, including the code to define functions which have already been defined, will remain mapped, consequently wasting memory.
-M
The compiled file is mapped into the shell’s memory when read. This
is done in such a way that multiple instances of the shell running
on the same host will share this mapped file. If neither -R
nor
-M
is given, the zcompile
builtin decides what to do based
on the size of the compiled file.
-k
-z
These options are used when the compiled file contains functions which
are to be autoloaded. If -z
is given, the
function will be autoloaded as if the KSH_AUTOLOAD
option is
not set, even if it is set at the time the compiled file is
read, while if the -k
is given, the function will be loaded as if
KSH_AUTOLOAD
is set. These options also take precedence over
any -k
or -z
options specified to the autoload
builtin. If
neither of these options is given, the function will be loaded as
determined by the setting of the KSH_AUTOLOAD
option at the time
the compiled file is read.
These options may also appear as many times as necessary between the listed
names to specify the loading style of all following functions, up to
the next -k
or -z
.
The created file always contains two versions of the compiled format, one for big-endian machines and one for small-endian machines. The upshot of this is that the compiled file is machine independent and if it is read or mapped, only one half of the file is actually used (and mapped).
zformat
See The zsh/zutil Module.
zftp
See The zsh/zftp Module.
zle
See Zle Builtins.
zmodload
[ -dL
] [ -s
] [ ... ] ¶zmodload -F
[ -alLme
-P
param ] module [ [+-
]feature ... ]zmodload -e
[ -A
] [ ... ]zmodload
[ -a
[ -bcpf
[ -I
] ] ] [ -iL
] ...zmodload
-u
[ -abcdpf
[ -I
] ] [ -iL
] ...zmodload
-A
[ -L
] [ modalias[=
module] ... ]zmodload
-R
modalias ...Performs operations relating to zsh’s loadable modules.
Loading of modules while the shell is running (‘dynamical loading’) is not
available on all operating systems, or on all installations on a particular
operating system, although the zmodload
command itself is always
available and can be used to manipulate modules built into versions of the
shell executable without dynamical loading.
Without arguments the names of all currently loaded binary modules are
printed. The -L
option causes this list to be in the form of a
series of zmodload
commands. Forms with arguments are:
zmodload
[ -is
] name ...zmodload
-u
[ -i
] name ...In the simplest case, zmodload
loads a binary module. The module must
be in a file with a name consisting of the specified name followed by
a standard suffix, usually ‘.so
’ (‘.sl
’ on HPUX).
If the module to be loaded is already loaded the duplicate module is
ignored. If zmodload
detects an inconsistency, such as an
invalid module name or circular dependency list, the current code block is
aborted. If it is available, the module is loaded if necessary, while if it
is not available, non-zero status is silently returned. The option
-i
is accepted for compatibility but has no effect.
The named module is searched for in the same way a command is, using
$module_path
instead of $path
. However, the path search is
performed even when the module name contains a ‘/
’, which it usually does.
There is no way to prevent the path search.
If the module supports features (see below), zmodload
tries to
enable all features when loading a module. If the module was successfully
loaded but not all features could be enabled, zmodload
returns status 2.
If the option -s
is given, no error is printed if the module was not
available (though other errors indicating a problem with the module are
printed). The return status indicates if the module was loaded. This
is appropriate if the caller considers the module optional.
With -u
, zmodload
unloads modules. The same name
must be given that was given when the module was loaded, but it is not
necessary for the module to exist in the file system.
The -i
option suppresses the error if the module is already
unloaded (or was never loaded).
Each module has a boot and a cleanup function. The module will not be loaded if its boot function fails. Similarly a module can only be unloaded if its cleanup function runs successfully.
zmodload -F
[ -almLe
-P
param ] module [ [+-
]feature ... ]zmodload -F
allows more selective control over the features provided
by modules. With no options apart from -F
, the module named
module is loaded, if it was not already loaded, and the list of
features is set to the required state. If no
features are specified, the module is loaded, if it was not already
loaded, but the state of features is unchanged. Each feature
may be preceded by a +
to turn the feature on, or -
to turn it
off; the +
is assumed if neither character is present.
Any feature not explicitly mentioned is left in its current state;
if the module was not previously loaded this means any such features will
remain disabled. The return status is zero if all features were
set, 1 if the module failed to load, and 2 if some features could
not be set (for example, a parameter couldn’t be added because there
was a different parameter of the same name) but the module was loaded.
The standard features are builtins, conditions, parameters and math
functions; these are indicated by the prefix ‘b:
’, ‘c:
’
(‘C:
’ for an infix condition), ‘p:
’ and ‘f:
’, respectively,
followed by the name that the corresponding feature would have in the
shell. For example, ‘b:strftime
’ indicates a builtin named
strftime
and p:EPOCHSECONDS
indicates a parameter named
EPOCHSECONDS
. The module may provide other (‘abstract’) features of
its own as indicated by its documentation; these have no prefix.
With -l
or -L
, features provided by the module are listed. With
-l
alone, a list of features together with their states is shown, one
feature per line. With -L
alone, a zmodload -F
command that would
cause enabled features of the module to be turned on is shown. With
-lL
, a zmodload -F
command that would cause all the features to be
set to their current state is shown. If one of these combinations is given
with the option -P
param then the parameter param is set to an
array of features, either features together with their state or (if
-L
alone is given) enabled features.
With the option -L
the module name may be omitted; then a list
of all enabled features for all modules providing features is printed
in the form of zmodload -F
commands. If -l
is also given,
the state of both enabled and disabled features is output in that form.
A set of features may be provided together with -l
or -L
and a
module name; in that case only the state of those features is
considered. Each feature may be preceded by +
or -
but the
character has no effect. If no set of features is provided, all
features are considered.
With -e
, the command first tests that the module is loaded;
if it is not, status 1 is returned. If the module is loaded,
the list of features given as an argument is examined. Any feature
given with no prefix is simply tested to see if the module provides it;
any feature given with a prefix +
or -
is tested to
see if is provided and in the given state. If the tests on all features
in the list succeed, status 0 is returned, else status 1.
With -m
, each entry in the given list of features is taken
as a pattern to be matched against the list of features provided
by the module. An initial +
or -
must be given explicitly.
This may not be combined with the -a
option as autoloads must
be specified explicitly.
With -a
, the given list of features is marked for autoload from
the specified module, which may not yet be loaded. An optional +
may appear before the feature name. If the feature is prefixed with
-
, any existing autoload is removed. The options -l
and -L
may be used to list autoloads. Autoloading is specific to individual
features; when the module is loaded only the requested feature is
enabled. Autoload requests are preserved if the module is
subsequently unloaded until an explicit ‘zmodload -Fa
module
-
feature’ is issued. It is not an error to request an autoload
for a feature of a module that is already loaded.
When the module is loaded each autoload is checked against the features
actually provided by the module; if the feature is not provided the
autoload request is deleted. A warning message is output; if the
module is being loaded to provide a different feature, and that autoload
is successful, there is no effect on the status of the current command.
If the module is already loaded at the time when zmodload -Fa
is
run, an error message is printed and status 1 returned.
zmodload -Fa
can be used with the -l
, -L
, -e
and
-P
options for listing and testing the existence of autoloadable
features. In this case -l
is ignored if -L
is specified.
zmodload -FaL
with no module name lists autoloads for all modules.
Note that only standard features as described above can be autoloaded; other features require the module to be loaded before enabling.
zmodload
-d
[ -L
] [ name ]zmodload
-d
name dep ...zmodload
-ud
name [ dep ... ]The -d
option can be used to specify module dependencies. The modules
named in the second and subsequent arguments will be loaded before the
module named in the first argument.
With -d
and one argument, all dependencies for that module are listed.
With -d
and no arguments, all module dependencies are listed. This
listing is by default in a Makefile-like format. The -L
option
changes this format to a list of zmodload -d
commands.
If -d
and -u
are both used, dependencies are removed. If only one
argument is given, all dependencies for that module are removed.
zmodload
-ab
[ -L
]zmodload
-ab
[ -i
] name [ builtin ... ]zmodload
-ub
[ -i
] builtin ...The -ab
option defines autoloaded builtins. It defines the specified
builtins. When any of those builtins is called, the module specified
in the first argument is loaded and all its features are enabled (for
selective control of features use ‘zmodload -F -a
’ as described
above). If only the name is given, one builtin is defined, with
the same name as the module. -i
suppresses the error if the builtin
is already defined or autoloaded, but not if another builtin of the
same name is already defined.
With -ab
and no arguments, all autoloaded builtins are listed, with the
module name (if different) shown in parentheses after the builtin name.
The -L
option changes this format to a list of zmodload -a
commands.
If -b
is used together with the -u
option, it removes builtins
previously defined with -ab
. This is only possible if the builtin is
not yet loaded. -i
suppresses the error if the builtin is already
removed (or never existed).
Autoload requests are retained if the module is subsequently unloaded
until an explicit ‘zmodload -ub
builtin’ is issued.
zmodload
-ac
[ -IL
]zmodload
-ac
[ -iI
] name [ cond ... ]zmodload
-uc
[ -iI
] cond ...The -ac
option is used to define autoloaded condition codes. The
cond strings give the names of the conditions defined by the
module. The optional -I
option is used to define infix condition
names. Without this option prefix condition names are defined.
If given no condition names, all defined names are listed (as a series of
zmodload
commands if the -L
option is given).
The -uc
option removes definitions for autoloaded conditions.
zmodload
-ap
[ -L
]zmodload
-ap
[ -i
] name [ parameter ... ]zmodload
-up
[ -i
] parameter ...The -p
option is like the -b
and -c
options, but makes
zmodload
work on autoloaded parameters instead.
zmodload
-af
[ -L
]zmodload
-af
[ -i
] name [ function ... ]zmodload
-uf
[ -i
] function ...The -f
option is like the -b
, -p
, and -c
options, but
makes zmodload
work on autoloaded math functions instead.
zmodload
-a
[ -L
]zmodload
-a
[ -i
] name [ builtin ... ]zmodload
-ua
[ -i
] builtin ...Equivalent to -ab
and -ub
.
zmodload -e
[ -A
] [ string ... ]The -e
option without arguments lists all loaded modules; if the -A
option is also given, module aliases corresponding to loaded modules are
also shown. If arguments are provided, nothing is printed;
the return status is set to zero if all strings given as arguments
are names of loaded modules and to one if at least on string is not
the name of a loaded module. This can be used to test for the
availability of things implemented by modules. In this case, any
aliases are automatically resolved and the -A
flag is not used.
zmodload
-A
[ -L
] [ modalias[=
module] ... ]For each argument, if both modalias and module are given,
define modalias to be an alias for the module module.
If the module modalias is ever subsequently requested, either via a
call to zmodload
or implicitly, the shell will attempt to load
module instead. If module is not given, show the definition of
modalias. If no arguments are given, list all defined module aliases.
When listing, if the -L
flag was also given, list the definition as a
zmodload
command to recreate the alias.
The existence of aliases for modules is completely independent of whether
the name resolved is actually loaded as a module: while the alias exists,
loading and unloading the module under any alias has exactly the same
effect as using the resolved name, and does not affect the connection
between the alias and the resolved name which can be removed either by
zmodload -R
or by redefining the alias. Chains of aliases (i.e. where
the first resolved name is itself an alias) are valid so long as these are
not circular. As the aliases take the same format as module names, they
may include path separators: in this case, there is no requirement for any
part of the path named to exist as the alias will be resolved first. For
example, ‘any/old/alias
’ is always a valid alias.
Dependencies added to aliased modules are actually added to the resolved module; these remain if the alias is removed. It is valid to create an alias whose name is one of the standard shell modules and which resolves to a different module. However, if a module has dependencies, it will not be possible to use the module name as an alias as the module will already be marked as a loadable module in its own right.
Apart from the above, aliases can be used in the zmodload
command
anywhere module names are required. However, aliases will not be
shown in lists of loaded modules with a bare ‘zmodload
’.
zmodload
-R
modalias ...For each modalias argument that was previously defined as a module
alias via zmodload -A
, delete the alias. If any was not defined, an
error is caused and the remainder of the line is ignored.
Note that zsh
makes no distinction between modules that were linked
into the shell and modules that are loaded dynamically. In both cases
this builtin command has to be used to make available the builtins and
other things defined by modules (unless the module is autoloaded on
these definitions). This is true even for systems that don’t support
dynamic loading of modules.
zparseopts
See The zsh/zutil Module.
zprof
See The zsh/zprof Module.
zpty
See The zsh/zpty Module.
zregexparse
See The zsh/zutil Module.
zsocket
zstyle
See The zsh/zutil Module.
ztcp
If the ZLE
option is set (which it is by default in interactive shells)
and the shell input is attached to the terminal, the user
is able to edit command lines.
There are two display modes. The first, multiline mode, is the
default. It only works if the TERM
parameter is set to a valid
terminal type that can move the cursor up. The second, single line
mode, is used if TERM
is invalid or incapable of moving the
cursor up, or if the SINGLE_LINE_ZLE
option is set.
This mode
is similar to ksh, and uses no termcap sequences. If TERM
is
"emacs", the ZLE
option will be unset by default.
The parameters BAUD
, COLUMNS
, and LINES
are also used by the
line editor. See
Parameters Used By The Shell.
The parameter zle_highlight
is also used by the line editor; see
Character Highlighting. Highlighting
of special characters and the region between the cursor and the
mark (as set with set-mark-command
in Emacs mode, or by visual-mode
in Vi mode) is enabled
by default; consult this reference for more information. Irascible
conservatives will wish to know that all highlighting may be disabled by
the following setting:
zle_highlight=(none)
In many places, references are made to the numeric argument
. This can
by default be entered in emacs mode by holding the alt key and typing
a number, or pressing escape before each digit, and in vi command mode
by typing the number before entering a command. Generally the numeric
argument causes the next command entered to be repeated the specified
number of times, unless otherwise noted below; this is implemented
by the digit-argument
widget. See also
Argumentsfor some other ways the numeric argument can be modified.
A keymap in ZLE contains a set of bindings between key sequences and ZLE commands. The empty key sequence cannot be bound.
There can be any number of keymaps at any time, and each keymap has one
or more names. If all of a keymap’s names are deleted, it disappears.
bindkey
can be used to manipulate keymap names.
Initially, there are eight keymaps:
emacs
EMACS emulation
viins
vi emulation - insert mode
vicmd
vi emulation - command mode
viopp
vi emulation - operator pending
visual
vi emulation - selection active
isearch
incremental search mode
command
read a command name
.safe
fallback keymap
The ‘.safe
’ keymap is special. It can never be altered, and the name
can never be removed. However, it can be linked to other names, which can
be removed. In the future other special keymaps may be added; users should
avoid using names beginning with ‘.
’ for their own keymaps.
In addition to these names, either ‘emacs
’ or ‘viins
’ is
also linked to the name ‘main
’. If one of the VISUAL
or
EDITOR
environment variables contain the string ‘vi
’ when the shell
starts up then it will be ‘viins
’, otherwise it will be ‘emacs
’.
bindkey
’s -e
and -v
options provide a convenient way to override this default choice.
When the editor starts up, it will select the ‘main
’ keymap.
If that keymap doesn’t exist, it will use ‘.safe
’ instead.
In the ‘.safe
’ keymap, each single key is bound to self-insert
,
except for ^J (line feed) and ^M (return) which are bound to accept-line
.
This is deliberately not pleasant to use; if you are using it, it
means you deleted the main keymap, and you should put it back.
When ZLE is reading a command from the terminal, it may read a sequence
that is bound to some command and is also a prefix of a longer bound string.
In this case ZLE will wait a certain time to see if more characters
are typed, and if not (or they don’t match any longer string) it will
execute the binding. This timeout is defined by the KEYTIMEOUT
parameter;
its default is 0.4 sec. There is no timeout if the prefix string is not
itself bound to a command.
The key timeout is also applied when ZLE is reading the bytes from a
multibyte character string when it is in the appropriate mode. (This
requires that the shell was compiled with multibyte mode enabled; typically
also the locale has characters with the UTF-8 encoding, although any
multibyte encoding known to the operating system is supported.) If the
second or a subsequent byte is not read within the timeout period, the
shell acts as if ?
were typed and resets the input state.
As well as ZLE commands, key sequences can be bound to other strings, by using
‘bindkey -s
’.
When such a sequence is read, the replacement string is pushed back as input,
and the command reading process starts again using these fake keystrokes.
This input can itself invoke further replacement strings, but in order to
detect loops the process will be stopped if there are twenty such replacements
without a real command being read.
A key sequence typed by the user can be turned into a command name for use
in user-defined widgets with the read-command
widget, described in
Miscellaneous below.
While for normal editing a single keymap is used exclusively, in many
modes a local keymap allows for some keys to be customised. For example,
in an incremental search mode, a binding in the isearch
keymap will
override a binding in the main
keymap but all keys that are not
overridden can still be used.
If a key sequence is defined in a local keymap, it will hide a key
sequence in the global keymap that is a prefix of that sequence. An
example of this occurs with the binding of iw
in viopp
as this
hides the binding of i
in vicmd
. However, a longer sequence in
the global keymap that shares the same prefix can still apply so for
example the binding of ^Xa
in the global keymap will be unaffected
by the binding of ^Xb
in the local keymap.
The ZLE module contains three related builtin commands. The bindkey
command manipulates keymaps and key bindings; the vared
command invokes
ZLE on the value of a shell parameter; and the zle
command manipulates
editing widgets and allows command line access to ZLE commands from within
shell functions.
bindkey
[ options ] -l
[ -L
] [ keymap ... ] ¶bindkey
[ options ] -d
bindkey
[ options ] -D
keymap ...bindkey
[ options ] -A
old-keymap new-keymapbindkey
[ options ] -N
new-keymap [ old-keymap ]bindkey
[ options ] -m
bindkey
[ options ] -r
in-string ...bindkey
[ options ] -s
in-string out-string ...bindkey
[ options ] in-string command ...bindkey
[ options ] [ in-string ]bindkey
’s options can be divided into three categories: keymap
selection for the current command, operation selection, and others. The
keymap selection options are:
-e
Selects keymap ‘emacs
’ for any operations by the current command,
and also links ‘emacs
’ to ‘main
’ so that it is selected by
default the next time the editor starts.
-v
Selects keymap ‘viins
’ for any operations by the current command,
and also links ‘viins
’ to ‘main
’ so that it is selected by default
the next time the editor starts.
-a
Selects keymap ‘vicmd
’ for any operations by the current command.
-M
keymapThe keymap specifies a keymap name that is selected for any operations by the current command.
If a keymap selection is required and none of the options above are used, the
‘main
’ keymap is used. Some operations do not permit a keymap to be
selected, namely:
-l
List all existing keymap names; if any arguments are given, list just those keymaps.
If the -L
option is also used, list in the form of bindkey
commands to create or link the keymaps. ‘bindkey -lL
main
’ shows which keymap is linked to ‘main
’, if any, and hence if
the standard emacs or vi emulation is in effect. This option does
not show the .safe
keymap because it cannot be created in that
fashion; however, neither is ‘bindkey -lL .safe
’ reported as an
error, it simply outputs nothing.
-d
Delete all existing keymaps and reset to the default state.
-D
keymap ...Delete the named keymaps.
-A
old-keymap new-keymapMake the new-keymap name an alias for old-keymap, so that both names refer to the same keymap. The names have equal standing; if either is deleted, the other remains. If there is already a keymap with the new-keymap name, it is deleted.
-N
new-keymap [ old-keymap ]Create a new keymap, named new-keymap. If a keymap already has that name, it is deleted. If an old-keymap name is given, the new keymap is initialized to be a duplicate of it, otherwise the new keymap will be empty.
To use a newly created keymap, it should be linked to main
. Hence
the sequence of commands to create and use a new keymap ‘mymap
’
initialized from the emacs
keymap (which remains unchanged) is:
bindkey -N mymap emacs bindkey -A mymap main
Note that while ‘bindkey -A
newmap main
’ will work when
newmap is emacs
or viins
, it will not work for vicmd
, as
switching from vi insert to command mode becomes impossible.
The following operations act on the ‘main
’ keymap if no keymap
selection option was given:
-m
Add the built-in set of meta-key bindings to the selected keymap.
Only keys that are unbound or bound to self-insert
are affected.
-r
in-string ...Unbind the specified in-strings in the selected keymap.
This is exactly equivalent to binding the strings to undefined-key
.
When -R
is also used, interpret the in-strings as ranges.
When -p
is also used, the in-strings specify prefixes. Any
binding that has the given in-string as a prefix, not including the
binding for the in-string itself, if any, will be removed. For
example,
bindkey -rpM viins '^['
will remove all bindings in the vi-insert keymap beginning with an escape
character (probably cursor keys), but leave the binding for the escape
character itself (probably vi-cmd-mode
). This is incompatible with the
option -R
.
-s
in-string out-string ...Bind each in-string to each out-string.
When in-string is typed, out-string will be
pushed back and treated as input to the line editor.
When -R
is also used, interpret the in-strings as ranges.
Note that both in-string and out-string are subject to the same form of interpretation, as described below.
Bind each in-string to each command.
When -R
is used, interpret the in-strings as ranges.
List key bindings. If an in-string is specified, the binding of
that string in the selected keymap is displayed. Otherwise, all key
bindings in the selected keymap are displayed. (As a special case,
if the -e
or -v
option is used alone, the keymap is not
displayed - the implicit linking of keymaps is the only thing that
happens.)
When the option -p
is used, the in-string must be present.
The listing shows all bindings which have the given key sequence as a
prefix, not including any bindings for the key sequence itself.
When the -L
option is used, the list is in the form of bindkey
commands to create the key bindings.
When the -R
option is used as noted above, a valid range consists of
two characters, with an optional ‘-
’ between them. All characters
between the two specified, inclusive, are bound as specified.
For either in-string or out-string, the following escape sequences are recognised:
\a
bell character
\b
backspace
\e
, \E
escape
\f
form feed
\n
linefeed (newline)
\r
carriage return
\t
horizontal tab
\v
vertical tab
\
NNNcharacter code in octal
\x
NNcharacter code in hexadecimal
\u
NNNNunicode character code in hexadecimal
\U
NNNNNNNNunicode character code in hexadecimal
\M
[-
]Xcharacter with meta bit set
\C
[-
]Xcontrol character
^
Xcontrol character
In all other cases, ‘\
’ escapes the following character. Delete is
written as ‘^?
’. Note that ‘\M^?
’ and ‘^\M?
’ are not the same,
and that (unlike emacs), the bindings ‘\M-
X’ and ‘\e
X’
are entirely distinct, although they are initialized to the same bindings
by ‘bindkey -m
’.
vared
[ -Aacghe
] [ -p
prompt ] [ -r
rprompt ]
[ -M
main-keymap ] [ -m
vicmd-keymap ]
[ -i
init-widget ] [ -f
finish-widget ]
[ -t
tty ] nameThe value of the parameter name is loaded into the edit
buffer, and the line editor is invoked. When the editor exits,
name is set to the string value returned by the editor.
When the -c
flag is given, the parameter is created if it doesn’t
already exist. The -a
flag may be given with -c
to create
an array parameter, or the -A
flag to create an associative array.
If the type of an existing parameter does not match the type to be
created, the parameter is unset and recreated. The -g
flag may
be given to suppress warnings from the WARN_CREATE_GLOBAL
and WARN_NESTED_VAR
options.
If an array or array slice is being edited, separator characters as defined
in $IFS
will be shown quoted with a backslash, as will backslashes
themselves. Conversely, when the edited text is split into an array, a
backslash quotes an immediately following separator character or backslash;
no other special handling of backslashes, or any handling of quotes, is
performed.
Individual elements of existing array or associative array parameters
may be edited by using subscript syntax on name. New elements are
created automatically, even without -c
.
If the -p
flag is given, the following string will be taken as
the prompt to display at the left. If the -r
flag is given,
the following string gives the prompt to display at the right. If the
-h
flag is specified, the history can be accessed from ZLE. If the
-e
flag is given, typing ^D
(Control-D) on an empty line
causes vared
to exit immediately with a non-zero return value.
The -M
option gives a keymap to link to the main
keymap during
editing, and the -m
option gives a keymap to link to the vicmd
keymap during editing. For vi-style editing, this allows a pair of keymaps
to override viins
and vicmd
. For emacs-style editing, only -M
is normally needed but the -m
option may still be used. On exit, the
previous keymaps will be restored.
Vared
calls the usual ‘zle-line-init
’ and ‘zle-line-finish
’
hooks before and after it takes control. Using the -i
and -f
options, it is possible to replace these with other custom widgets.
If ‘-t
tty’ is given, tty is the name of a terminal device
to be used instead of the default /dev/tty
. If tty does not
refer to a terminal an error is reported.
zle
¶zle
-l
[ -L
| -a
] [ string ... ]zle
-D
widget ...zle
-A
old-widget new-widgetzle
-N
widget [ function ]zle
-f
flag [ flag... ]zle
-C
widget completion-widget functionzle
-R
[ -c
] [ display-string ] [ string ... ]zle
-M
stringzle
-U
stringzle
-K
keymapzle
-F
[ -L
| -w
] [ fd [ handler ] ]zle
-I
zle
-T
[ tc
function | -r
tc
| -L
]zle
widget [ -n
num ] [ -f
flag ] [ -Nw
] [ -K
keymap ] args ...The zle
builtin performs a number of different actions concerning
ZLE.
With no options and no arguments, only the return status will be set. It is zero if ZLE is currently active and widgets could be invoked using this builtin command and non-zero otherwise. Note that even if non-zero status is returned, zle may still be active as part of the completion system; this does not allow direct calls to ZLE widgets.
Otherwise, which operation it performs depends on its options:
-l
[ -L
| -a
] [ string ]List all existing user-defined widgets. If the -L
option is used, list in the form of zle
commands to create the widgets.
When combined with the -a
option, all widget names are listed,
including the builtin ones. In this case the -L
option is ignored.
If at least one string is given, and -a
is present or -L
is
not used, nothing will be printed. The return status will be zero if
all strings are names of existing widgets and non-zero if at least one
string is not a name of a defined widget. If -a
is also
present, all widget names are used for the comparison including builtin
widgets, else only user-defined widgets are used.
If at least one string is present and the -L
option is used,
user-defined widgets matching any string are listed in the form of
zle
commands to create the widgets.
-D
widget ...Delete the named widgets.
-A
old-widget new-widgetMake the new-widget name an alias for old-widget, so that both names refer to the same widget. The names have equal standing; if either is deleted, the other remains. If there is already a widget with the new-widget name, it is deleted.
-N
widget [ function ]Create a user-defined widget. If there is already a widget with the specified name, it is overwritten. When the new widget is invoked from within the editor, the specified shell function is called. If no function name is specified, it defaults to the same name as the widget. For further information, see Zle Widgets.
-f
flag [ flag... ]Set various flags on the running widget. Possible values for flag are:
yank
for indicating that the widget has yanked text into the buffer.
If the widget is wrapping an existing internal widget, no further
action is necessary, but if it has inserted the text manually, then it
should also take care to set YANK_START
and YANK_END
correctly.
yankbefore
does the same but is used when the yanked text appears
after the cursor.
kill
for indicating that text has been killed into the cutbuffer.
When repeatedly invoking a kill widget, text is appended to the cutbuffer
instead of replacing it, but when wrapping such widgets, it is necessary
to call ‘zle -f kill
’ to retain this effect.
vichange
for indicating that the widget represents a vi change that
can be repeated as a whole with ‘vi-repeat-change
’. The flag should be set
early in the function before inspecting the value of NUMERIC
or invoking
other widgets. This has no effect for a widget invoked from insert mode. If
insert mode is active when the widget finishes, the change extends until next
returning to command mode.
-C
widget completion-widget function ¶Create a user-defined completion widget named widget. The completion widget will behave like the built-in completion-widget whose name is given as completion-widget. To generate the completions, the shell function function will be called. For further information, see Completion Widgets.
-R
[ -c
] [ display-string ] [ string ... ]Redisplay the command line. If a display-string is given and not empty, this is shown in the status line (immediately below the line being edited).
If the optional strings are given they are listed below the
prompt in the same way as completion lists are printed. If no
strings are given but the -c
option is used such a list is
cleared.
Note that immediately after returning from running widgets, the command line will be redisplayed and the strings displayed will be erased. Therefore, this option is only useful for widgets that do not exit immediately after using it.
This command can safely be called outside user defined widgets; if zle is active, the display will be refreshed, while if zle is not active, the command has no effect. In this case there will usually be no other arguments.
The status is zero if zle was active, else one.
-M
stringAs with the -R
option, the string will be displayed below the
command line; unlike the -R
option, the string will not be put into
the status line but will instead be printed normally below the
prompt. This means that the string will still be displayed after
the widget returns (until it is overwritten by subsequent commands).
-U
stringThis pushes the characters in the string onto the input stack of ZLE. After the widget currently executed finishes ZLE will behave as if the characters in the string were typed by the user.
As ZLE uses a stack, if this option is used repeatedly the last string pushed onto the stack will be processed first. However, the characters in each string will be processed in the order in which they appear in the string.
-K
keymapSelects the keymap named keymap. An error message will be displayed if there is no such keymap.
This keymap selection affects the interpretation of following keystrokes
within this invocation of ZLE. Any following invocation (e.g., the next
command line) will start as usual with the ‘main
’ keymap selected.
-F
[ -L
| -w
] [ fd [ handler ] ]Only available if your system supports one of the ‘poll’ or ‘select’ system calls; most modern systems do.
Installs handler (the name of a shell function) to handle input from file descriptor fd. Installing a handler for an fd which is already handled causes the existing handler to be replaced. Any number of handlers for any number of readable file descriptors may be installed. Note that zle makes no attempt to check whether this fd is actually readable when installing the handler. The user must make their own arrangements for handling the file descriptor when zle is not active.
When zle is attempting to read data, it will examine both the terminal and
the list of handled fd’s. If data becomes available on a handled
fd, zle calls handler with the fd which is ready for reading
as the first argument. Under normal circumstances this is the only
argument, but if an error was detected, a second argument provides
details: ‘hup
’ for a disconnect, ‘nval
’ for a closed or otherwise
invalid descriptor, or ‘err
’ for any other condition. Systems that
support only the ‘select’ system call always use ‘err
’.
If the option -w
is also given, the handler is instead a line
editor widget, typically a shell function made into a widget using
‘zle -N
’. In that case handler can use all the facilities of zle
to update the current editing line. Note, however, that as handling fd
takes place at a low level changes to the display will not automatically
appear; the widget should call ‘zle -R
’ to force redisplay. As of this
writing, widget handlers only support a single argument and thus are never
passed a string for error state, so widgets must be prepared to test the
descriptor themselves.
If either type of handler produces output to the terminal, it should call
‘zle -I
’ before doing so (see below). Handlers should not attempt to
read from the terminal.
If no handler is given, but an fd is present, any handler for that fd is removed. If there is none, an error message is printed and status 1 is returned.
If no arguments are given, or the -L
option is supplied, a list of
handlers is printed in a form which can be stored for later execution.
An fd (but not a handler) may optionally be given with the -L
option; in this case, the function will list the handler if any, else
silently return status 1.
Note that this feature should be used with care. Activity on one of the fd’s which is not properly handled can cause the terminal to become unusable. Removing an fd handler from within a signal trap may cause unpredictable behavior.
Here is a simple example of using this feature. A connection to a remote TCP port is created using the ztcp command; see The zsh/net/tcp Module. Then a handler is installed which simply prints out any data which arrives on this connection. Note that ‘select’ will indicate that the file descriptor needs handling if the remote side has closed the connection; we handle that by testing for a failed read.
if ztcp pwspc 2811; then tcpfd=$REPLY handler() { zle -I local line if ! read -r line <&$1; then # select marks this fd if we reach EOF, # so handle this specially. print "[Read on fd $1 failed, removing.]" >&2 zle -F $1 return 1 fi print -r - $line } zle -F $tcpfd handler fi
-I
Unusually, this option is most useful outside ordinary widget functions, though it may be used within if normal output to the terminal is required. It invalidates the current zle display in preparation for output; typically this will be from a trap function. It has no effect if zle is not active. When a trap exits, the shell checks to see if the display needs restoring, hence the following will print output in such a way as not to disturb the line being edited:
TRAPUSR1() { # Invalidate zle display [[ -o zle ]] && zle -I # Show output print Hello }
In general, the trap function may need to test whether zle is active before
using this method (as shown in the example), since the zsh/zle
module
may not even be loaded; if it is not, the command can be skipped.
It is possible to call ‘zle -I
’ several times before control is
returned to the editor; the display will only be invalidated the first time
to minimise disruption.
Note that there are normally better ways of manipulating the display from
within zle widgets; see, for example, ‘zle -R
’ above.
The returned status is zero if zle was invalidated, even though
this may have been by a previous call to ‘zle -I
’ or by a system
notification. To test if a zle widget may be called at this point, execute
zle
with no arguments and examine the return status.
-T
This is used to add, list or remove internal transformations on the processing performed by the line editor. It is typically used only for debugging or testing and is therefore of little interest to the general user.
‘zle -T
transformation func’ specifies that the
given transformation (see below) is effected by shell function
func.
‘zle -Tr
transformation’ removes the given transformation
if it was present (it is not an error if none was).
‘zle -TL
’ can be used to list all transformations currently in
operation.
Currently the only transformation is tc
. This is used instead
of outputting termcap codes to the terminal. When the transformation is
in operation the shell function is passed the termcap code that would be
output as its first argument; if the operation required a numeric
argument, that is passed as a second argument. The function should set
the shell variable REPLY
to the transformed termcap code. Typically
this is used to produce some simply formatted version of the code and
optional argument for debugging or testing. Note that this
transformation is not applied to other non-printing characters such as
carriage returns and newlines.
-n
num ] [ -f
flag ] [ -Nw
] [ -K
keymap ] args ...Invoke the specified widget. This can only be done when ZLE is active; normally this will be within a user-defined widget.
With the options -n
and -N
, the current numeric argument will be
saved and then restored after the call to widget; ‘-n
num’
sets the numeric argument temporarily to num, while ‘-N
’ sets it
to the default, i.e. as if there were none.
With the option -K
, keymap will be used as the current keymap
during the execution of the widget. The previous keymap will be
restored when the widget exits.
Normally, calling a widget in this way does not set the special
parameter WIDGET
and related parameters, so that the environment
appears as if the top-level widget called by the user were still
active. With the option -w
, WIDGET
and related parameters are set
to reflect the widget being executed by the zle
call.
Normally, when widget returns the special parameter LASTWIDGET
will
point to it. This can be inhibited by passing the option -f nolast
.
Any further arguments will be passed to the widget; note that as
standard argument handling is performed, any general argument list
should be preceded by -
-
. If it is a shell
function, these are passed down as positional parameters; for builtin
widgets it is up to the widget in question what it does with them.
Currently arguments are only handled by the incremental-search commands,
the history-search-forward
and -backward
and the corresponding
functions prefixed by vi-
, and by universal-argument
. No error is
flagged if the command does not use the arguments, or only uses some of
them.
The return status reflects the success or failure of the operation carried out by the widget, or if it is a user-defined widget the return status of the shell function.
A non-zero return status causes the shell to beep when the widget exits,
unless the BEEP
options was unset or the widget was called via the
zle
command. Thus if a user defined widget requires an immediate beep,
it should call the beep
widget directly.
All actions in the editor are performed by ‘widgets’. A widget’s job is simply to perform some small action. The ZLE commands that key sequences in keymaps are bound to are in fact widgets. Widgets can be user-defined or built in.
The standard widgets built into ZLE are listed in
Standard Widgets.
Other built-in widgets can be defined by other modules (see
Zsh Modules). Each built-in widget has two names: its normal canonical name, and the
same name preceded by a ‘.
’. The ‘.
’ name is special: it can’t be
rebound to a different widget. This makes the widget available even when
its usual name has been redefined.
User-defined widgets are defined using ‘zle -N
’, and implemented
as shell functions. When the widget is executed, the corresponding
shell function is executed, and can perform editing (or other) actions.
It is recommended that user-defined widgets should not have names
starting with ‘.
’.
User-defined widgets, being implemented as shell functions,
can execute any normal shell command. They can also run other widgets
(whether built-in or user-defined) using the zle
builtin command. The
standard input of the function is redirected from /dev/null to prevent
external commands from unintentionally blocking ZLE by reading from the
terminal, but read -k
or read -q
can be used to read characters.
Finally, they can examine and edit the ZLE buffer being edited by reading
and setting the special parameters described below.
These special parameters are always available in widget functions, but
are not in any way special outside ZLE. If they have some normal value
outside ZLE, that value is temporarily inaccessible, but will return
when the widget function exits. These special parameters in fact have
local scope, like parameters created in a function using local
.
Inside completion widgets and traps called while ZLE is active, these parameters are available read-only.
Note that the parameters appear as local to any ZLE widget in which they appear. Hence if it is desired to override them this needs to be done within a nested function:
widget-function() { # $WIDGET here refers to the special variable # that is local inside widget-function () { # This anonymous nested function allows WIDGET # to be used as a local variable. The -h # removes the special status of the variable. local -h WIDGET } }
BUFFER
(scalar) ¶The entire contents of the edit buffer. If it is written to, the cursor remains at the same offset, unless that would put it outside the buffer.
BUFFERLINES
(integer) ¶The number of screen lines needed for the edit buffer currently displayed on screen (i.e. without any changes to the preceding parameters done after the last redisplay); read-only.
CONTEXT
(scalar) ¶The context in which zle was called to read a line; read-only. One of the values:
start
The start of a command line (at prompt PS1
).
cont
A continuation to a command line (at prompt PS2
).
select
In a select
loop (at prompt PS3
).
vared
Editing a variable in vared
.
CURSOR
(integer) ¶The offset of the cursor, within the edit buffer. This is in the range
0 to $#BUFFER
, and is by definition equal to $#LBUFFER
.
Attempts to move the cursor outside the buffer will result in the
cursor being moved to the appropriate end of the buffer.
CUTBUFFER
(scalar) ¶The last item cut using one of the ‘kill-
’ commands; the string
which the next yank would insert in the line. Later entries in
the kill ring are in the array killring
. Note that the
command ‘zle copy-region-as-kill
string’ can be used to
set the text of the cut buffer from a shell function and cycle the kill
ring in the same way as interactively killing text.
HISTNO
(integer) ¶The current history number. Setting this has the same effect as
moving up or down in the history to the corresponding history line.
An attempt to set it is ignored if the line is not stored in the
history. Note this is not the same as the parameter HISTCMD
,
which always gives the number of the history line being added to the main
shell’s history. HISTNO
refers to the line being retrieved within
zle.
ISEARCHMATCH_ACTIVE
(integer) ¶ISEARCHMATCH_START
(integer)ISEARCHMATCH_END
(integer)ISEARCHMATCH_ACTIVE
indicates whether a part of the BUFFER
is
currently matched by an incremental search pattern. ISEARCHMATCH_START
and ISEARCHMATCH_END
give the location of the matched part and are
in the same units as CURSOR
. They are only valid for reading
when ISEARCHMATCH_ACTIVE
is non-zero.
All parameters are read-only.
KEYMAP
(scalar) ¶The name of the currently selected keymap; read-only.
KEYS
(scalar) ¶The keys typed to invoke this widget, as a literal string; read-only.
KEYS_QUEUED_COUNT
(integer) ¶The number of bytes pushed back to the input queue and therefore
available for reading immediately before any I/O is done; read-only.
See also PENDING
; the two values are distinct.
killring
(array) ¶The array of previously killed items, with the most recently killed first.
This gives the items that would be retrieved by a yank-pop
in the
same order. Note, however, that the most recently killed item is in
$CUTBUFFER
; $killring
shows the array of previous entries.
The default size for the kill ring is eight, however the length may be
changed by normal array operations. Any empty string in the kill ring is
ignored by the yank-pop
command, hence the size of the array
effectively sets the maximum length of the kill ring, while the number of
non-zero strings gives the current length, both as seen by the user at the
command line.
LASTABORTEDSEARCH
(scalar) ¶The last search string used by an interactive search that was aborted by the user (status 3 returned by the search widget).
LASTSEARCH
(scalar) ¶The last search string used by an interactive search; read-only. This is set even if the search failed (status 0, 1 or 2 returned by the search widget), but not if it was aborted by the user.
LASTWIDGET
(scalar) ¶The name of the last widget that was executed; read-only.
LBUFFER
(scalar) ¶The part of the buffer that lies to the left of the cursor position.
If it is assigned to, only that part of the buffer is replaced, and the
cursor remains between the new $LBUFFER
and the old $RBUFFER
.
MARK
(integer) ¶Like CURSOR
, but for the mark. With vi-mode operators that wait for
a movement command to select a region of text, setting MARK
allows
the selection to extend in both directions from the initial cursor
position.
NUMERIC
(integer) ¶The numeric argument. If no numeric argument was given, this parameter
is unset. When this is set inside a widget function, builtin widgets
called with the zle
builtin command will use the value
assigned. If it is unset inside a widget function, builtin widgets
called behave as if no numeric argument was given.
PENDING
(integer) ¶The number of bytes pending for input, i.e. the number of bytes which have
already been typed and can immediately be read. On systems where the shell
is not able to get this information, this parameter will always have a
value of zero. Read-only. See also KEYS_QUEUED_COUNT
; the two
values are distinct.
PREBUFFER
(scalar) ¶In a multi-line input at the secondary prompt, this read-only parameter contains the contents of the lines before the one the cursor is currently in.
PREDISPLAY
(scalar) ¶Text to be displayed before the start of the editable text buffer. This does not have to be a complete line; to display a complete line, a newline must be appended explicitly. The text is reset on each new invocation (but not recursive invocation) of zle.
POSTDISPLAY
(scalar) ¶Text to be displayed after the end of the editable text buffer. This does not have to be a complete line; to display a complete line, a newline must be prepended explicitly. The text is reset on each new invocation (but not recursive invocation) of zle.
RBUFFER
(scalar) ¶The part of the buffer that lies to the right of the cursor position.
If it is assigned to, only that part of the buffer is replaced, and the
cursor remains between the old $LBUFFER
and the new $RBUFFER
.
REGION_ACTIVE
(integer) ¶Indicates if the region is currently active. It can be assigned 0 or 1 to deactivate and activate the region respectively. A value of 2 activates the region in line-wise mode with the highlighted text extending for whole lines only; see Character Highlighting.
region_highlight
(array) ¶Each element of this array may be set to a string that describes
highlighting for an arbitrary region of the command line that will
take effect the next time the command line is redisplayed. Highlighting
of the non-editable parts of the command line in PREDISPLAY
and POSTDISPLAY
are possible, but note that the P
flag
is needed for character indexing to include PREDISPLAY
.
Each string consists of the following whitespace-separated parts:
P
’ to signify that the start and end offset that
follow include any string set by the PREDISPLAY
special parameter;
this is needed if the predisplay string itself is to be highlighted.
Whitespace between the ‘P
’ and the start offset is optional.
CURSOR
.
CURSOR
.
zle_highlight
, see
Character Highlighting;
for example, standout
or fg=red,bold
.
memo=
token’.
The token consists of everything between the ‘=
’ and the next
whitespace, comma, NUL, or the end of the string.
The token is preserved verbatim but not parsed in any way.
Plugins may use this to identify array elements they have added: for example,
a plugin might set token to its (the plugin’s) name and then use
‘region_highlight=( ${region_highlight:#*memo=
token} )
’
in order to remove array elements it have added.
(This example uses the ‘${
name:#
pattern}
’ array-grepping
syntax described in
Parameter Expansion.)
For example,
region_highlight=("P0 20 bold memo=foobar")
specifies that the first twenty characters of the text including any predisplay string should be highlighted in bold.
Note that the effect of region_highlight
is not saved and disappears
as soon as the line is accepted.
Note that zsh 5.8 and older do not support the ‘memo=
token’ field
and may misparse the third (highlight specification) field when a memo
is given.
The final highlighting on the command line depends on both region_highlight
and zle_highlight
; see
Character Highlighting for details.
registers
(associative array) ¶The contents of each of the vi register buffers. These are
typically set using vi-set-buffer
followed by a delete, change or
yank command.
SUFFIX_ACTIVE
(integer) ¶SUFFIX_START
(integer)SUFFIX_END
(integer)SUFFIX_ACTIVE
indicates whether an auto-removable completion suffix
is currently active. SUFFIX_START
and SUFFIX_END
give the
location of the suffix and are in the same units as CURSOR
. They are
only valid for reading when SUFFIX_ACTIVE
is non-zero.
All parameters are read-only.
UNDO_CHANGE_NO
(integer) ¶A number representing the state of the undo history. The only use
of this is passing as an argument to the undo
widget in order to
undo back to the recorded point. Read-only.
UNDO_LIMIT_NO
(integer) ¶A number corresponding to an existing change in the undo history;
compare UNDO_CHANGE_NO
. If this is set to a value greater
than zero, the undo
command will not allow the line to
be undone beyond the given change number. It is still possible
to use ‘zle undo
change’ in a widget to undo beyond
that point; in that case, it will not be possible to undo at
all until UNDO_LIMIT_NO
is reduced. Set to 0 to disable the limit.
A typical use of this variable in a widget function is as follows (note the additional function scope is required):
() { local UNDO_LIMIT_NO=$UNDO_CHANGE_NO # Perform some form of recursive edit. }
WIDGET
(scalar) ¶The name of the widget currently being executed; read-only.
WIDGETFUNC
(scalar) ¶The name of the shell function that implements a widget defined with
either zle -N
or zle -C
. In the former case, this is the second
argument to the zle -N
command that defined the widget, or
the first argument if there was no second argument. In the latter case
this is the third argument to the zle -C
command that defined the
widget. Read-only.
WIDGETSTYLE
(scalar) ¶Describes the implementation behind the completion widget currently being
executed; the second argument that followed zle -C
when the widget was
defined. This is the name of a builtin completion widget. For widgets
defined with zle -N
this is set to the empty string. Read-only.
YANK_ACTIVE
(integer) ¶YANK_START
(integer)YANK_END
(integer)YANK_ACTIVE
indicates whether text has just been yanked (pasted)
into the buffer. YANK_START
and YANK_END
give the location of
the pasted text and are in the same units as CURSOR
. They are only
valid for reading when YANK_ACTIVE
is non-zero. They can also be
assigned by widgets that insert text in a yank-like fashion, for example
wrappers of bracketed-paste
. See also zle -f
.
YANK_ACTIVE
is read-only.
ZLE_RECURSIVE
(integer) ¶Usually zero, but incremented inside any instance of
recursive-edit
. Hence indicates the current recursion level.
ZLE_RECURSIVE
is read-only.
ZLE_STATE
(scalar) ¶Contains a set of space-separated words that describe the current zle
state.
Currently, the states shown are the insert mode as set by the
overwrite-mode
or vi-replace
widgets and whether history commands
will visit imported entries as controlled by the set-local-history widget.
The string contains ‘insert
’ if characters to be inserted on the
command line move existing characters to the right or ‘overwrite
’
if characters to be inserted overwrite existing characters. It contains
‘localhistory
’ if only local history commands will be visited or
‘globalhistory
’ if imported history commands will also be visited.
The substrings are sorted in alphabetical order so that if you want to test for two specific substrings in a future-proof way, you can do match by doing:
if [[ $ZLE_STATE == *globalhistory*insert* ]]; then ...; fi
There are a few user-defined widgets which are special to the shell. If they do not exist, no special action is taken. The environment provided is identical to that for any other editing widget.
zle-isearch-exit
¶Executed at the end of incremental search at the point where the isearch
prompt is removed from the display. See zle-isearch-update
for
an example.
zle-isearch-update
¶Executed within incremental search when the display is about to be
redrawn. Additional output below the incremental search prompt can be
generated by using ‘zle -M
’ within the widget. For example,
zle-isearch-update() { zle -M "Line $HISTNO"; } zle -N zle-isearch-update
Note the line output by ‘zle -M
’ is not deleted on exit from
incremental search. This can be done from a zle-isearch-exit
widget:
zle-isearch-exit() { zle -M ""; } zle -N zle-isearch-exit
zle-line-pre-redraw
¶Executed whenever the input line is about to be redrawn, providing an opportunity to update the region_highlight array.
zle-line-init
¶Executed every time the line editor is started to read a new line of input. The following example puts the line editor into vi command mode when it starts up.
zle-line-init() { zle -K vicmd; } zle -N zle-line-init
(The command inside the function sets the keymap directly; it is
equivalent to zle vi-cmd-mode
.)
zle-line-finish
¶This is similar to zle-line-init
but is executed every time the
line editor has finished reading a line of input.
zle-history-line-set
¶Executed when the history line changes.
zle-keymap-select
¶Executed every time the keymap changes, i.e. the special parameter
KEYMAP
is set to a different value, while the line editor is active.
Initialising the keymap when the line editor starts does not cause the
widget to be called.
The value $KEYMAP
within the function reflects the new keymap. The
old keymap is passed as the sole argument.
This can be used for detecting switches between the vi command
(vicmd
) and insert (usually main
) keymaps.
The following is a list of all the standard widgets,
and their default bindings in emacs mode,
vi command mode and vi insert mode
(the ‘emacs
’, ‘vicmd
’ and ‘viins
’ keymaps, respectively).
Note that cursor keys are bound to movement keys in all three keymaps;
the shell assumes that the cursor keys send the key sequences reported
by the terminal-handling library (termcap or terminfo). The key sequences
shown in the list are those based on the VT100, common on many modern
terminals, but in fact these are not necessarily bound. In the case of the
viins
keymap, the initial escape character of the sequences serves also
to return to the vicmd
keymap: whether this happens is determined by
the KEYTIMEOUT
parameter, see Parameters.
vi-backward-blank-word
(unbound) (B
) (unbound) ¶Move backward one word, where a word is defined as a series of non-blank characters.
vi-backward-blank-word-end
(unbound) (gE
) (unbound) ¶Move to the end of the previous word, where a word is defined as a series of non-blank characters.
backward-char
(^B ESC-[D
) (unbound) (unbound) ¶Move backward one character.
vi-backward-char
(unbound) (^H h ^?
) (ESC-[D
) ¶Move backward one character, without changing lines.
backward-word
(ESC-B ESC-b
) (unbound) (unbound) ¶Move to the beginning of the previous word.
emacs-backward-word
¶Move to the beginning of the previous word.
vi-backward-word
(unbound) (b
) (unbound) ¶Move to the beginning of the previous word, vi-style.
vi-backward-word-end
(unbound) (ge
) (unbound) ¶Move to the end of the previous word, vi-style.
beginning-of-line
(^A
) (unbound) (unbound) ¶Move to the beginning of the line. If already at the beginning of the line, move to the beginning of the previous line, if any.
vi-beginning-of-line
¶Move to the beginning of the line, without changing lines.
down-line
(unbound) (unbound) (unbound) ¶Move down a line in the buffer.
end-of-line
(^E
) (unbound) (unbound) ¶Move to the end of the line. If already at the end of the line, move to the end of the next line, if any.
vi-end-of-line
(unbound) ($
) (unbound) ¶Move to the end of the line. If an argument is given to this command, the cursor will be moved to the end of the line (argument - 1) lines down.
vi-forward-blank-word
(unbound) (W
) (unbound) ¶Move forward one word, where a word is defined as a series of non-blank characters.
vi-forward-blank-word-end
(unbound) (E
) (unbound) ¶Move to the end of the current word, or, if at the end of the current word, to the end of the next word, where a word is defined as a series of non-blank characters.
forward-char
(^F ESC-[C
) (unbound) (unbound) ¶Move forward one character.
vi-forward-char
(unbound) (space l
) (ESC-[C
) ¶Move forward one character.
vi-find-next-char
(^X^F
) (f
) (unbound) ¶Read a character from the keyboard, and move to the next occurrence of it in the line.
vi-find-next-char-skip
(unbound) (t
) (unbound) ¶Read a character from the keyboard, and move to the position just before the next occurrence of it in the line.
vi-find-prev-char
(unbound) (F
) (unbound) ¶Read a character from the keyboard, and move to the previous occurrence of it in the line.
vi-find-prev-char-skip
(unbound) (T
) (unbound) ¶Read a character from the keyboard, and move to the position just after the previous occurrence of it in the line.
vi-first-non-blank
(unbound) (^
) (unbound) ¶Move to the first non-blank character in the line.
vi-forward-word
(unbound) (w
) (unbound) ¶Move forward one word, vi-style.
forward-word
(ESC-F ESC-f
) (unbound) (unbound) ¶Move to the beginning of the next word.
The editor’s idea of a word is specified with the WORDCHARS
parameter.
emacs-forward-word
¶Move to the end of the next word.
vi-forward-word-end
(unbound) (e
) (unbound) ¶Move to the end of the next word.
vi-goto-column
(ESC-|
) (|
) (unbound) ¶Move to the column specified by the numeric argument.
vi-goto-mark
(unbound) (`
) (unbound) ¶Move to the specified mark.
vi-goto-mark-line
(unbound) ('
) (unbound) ¶Move to beginning of the line containing the specified mark.
vi-repeat-find
(unbound) (;
) (unbound) ¶Repeat the last vi-find
command.
vi-rev-repeat-find
(unbound) (,
) (unbound) ¶Repeat the last vi-find
command in the opposite direction.
up-line
(unbound) (unbound) (unbound) ¶Move up a line in the buffer.
beginning-of-buffer-or-history
(ESC-<
) (gg
) (unbound) ¶Move to the beginning of the buffer, or if already there, move to the first event in the history list.
beginning-of-line-hist
¶Move to the beginning of the line. If already at the beginning of the buffer, move to the previous history line.
beginning-of-history
¶Move to the first event in the history list.
down-line-or-history
(^N ESC-[B
) (j
) (ESC-[B
) ¶Move down a line in the buffer, or if already at the bottom line, move to the next event in the history list.
vi-down-line-or-history
(unbound) (+
) (unbound) ¶Move down a line in the buffer, or if already at the bottom line, move to the next event in the history list. Then move to the first non-blank character on the line.
down-line-or-search
¶Move down a line in the buffer, or if already at the bottom line, search forward in the history for a line beginning with the first word in the buffer.
If called from a function by the zle
command with arguments, the first
argument is taken as the string for which to search, rather than the
first word in the buffer.
down-history
(unbound) (^N
) (unbound) ¶Move to the next event in the history list.
history-beginning-search-backward
¶Search backward in the history for a line beginning with the current line up to the cursor. This leaves the cursor in its original position.
end-of-buffer-or-history
(ESC->
) (unbound) (unbound) ¶Move to the end of the buffer, or if already there, move to the last event in the history list.
end-of-line-hist
¶Move to the end of the line. If already at the end of the buffer, move to the next history line.
end-of-history
¶Move to the last event in the history list.
vi-fetch-history
(unbound) (G
) (unbound) ¶Fetch the history line specified by the numeric argument. This defaults to the current history line (i.e. the one that isn’t history yet).
history-incremental-search-backward
(^R ^Xr
) (unbound) (unbound) ¶Search backward incrementally for a specified string. The search is
case-insensitive if the search string does not have uppercase letters and no
numeric argument was given. The string may begin with ‘^
’ to anchor the
search to the beginning of the line. When called from a user-defined
function returns the following statuses: 0, if the search succeeded;
1, if the search failed; 2, if the search term was a bad pattern;
3, if the search was aborted by the send-break
command.
A restricted set of editing functions
is available in the mini-buffer. Keys are looked up in the special
isearch
keymap, and if not found there in the main keymap (note
that by default the isearch
keymap is empty).
An interrupt signal, as defined by the stty
setting, will stop the search and go back to the original line. An undefined
key will have the same effect. Note that the following always
perform the same task within incremental searches and cannot be
replaced by user defined widgets, nor can the set of functions
be extended. The supported functions are:
accept-and-hold
accept-and-infer-next-history
accept-line
accept-line-and-down-history
Perform the usual function after exiting incremental search. The command line displayed is executed.
backward-delete-char
vi-backward-delete-char
Back up one place in the search history. If the search has been repeated this does not immediately erase a character in the minibuffer.
accept-search
Exit incremental search, retaining the command line but performing no further action. Note that this function is not bound by default and has no effect outside incremental search.
backward-delete-word
backward-kill-word
vi-backward-kill-word
Back up one character in the minibuffer; if multiple searches
have been performed since the character was inserted the search
history is rewound to the point just before the character was
entered. Hence this has the effect of repeating
backward-delete-char
.
clear-screen
Clear the screen, remaining in incremental search mode.
history-incremental-search-backward
Find the next occurrence of the contents of the mini-buffer. If the mini-buffer is empty, the most recent previously used search string is reinstated.
history-incremental-search-forward
Invert the sense of the search.
magic-space
Inserts a non-magical space.
quoted-insert
vi-quoted-insert
Quote the character to insert into the minibuffer.
redisplay
Redisplay the command line, remaining in incremental search mode.
vi-cmd-mode
Select the ‘vicmd
’ keymap;
the ‘main
’ keymap (insert mode) will be selected initially.
In addition, the modifications that were made while in vi insert mode are merged to form a single undo event.
vi-repeat-search
vi-rev-repeat-search
Repeat the search. The direction of the search is indicated in the mini-buffer.
Any character that is not bound to one of the above functions, or
self-insert
or self-insert-unmeta
, will cause the mode to be
exited. The character is then looked up and executed in the keymap in
effect at that point.
When called from a widget function by the zle
command, the incremental
search commands can take a string argument. This will be treated as a
string of keys, as for arguments to the bindkey
command, and used as
initial input for the command. Any characters in the string which are
unused by the incremental search will be silently ignored. For example,
zle history-incremental-search-backward forceps
will search backwards for forceps
, leaving the minibuffer containing
the string ‘forceps
’.
history-incremental-search-forward
(^S ^Xs
) (unbound) (unbound) ¶Search forward incrementally for a specified string. The search is
case-insensitive if the search string does not have uppercase letters and no
numeric argument was given. The string may begin with ‘^
’ to anchor the
search to the beginning of the line. The functions available in the
mini-buffer are the same as for history-incremental-search-backward
.
history-incremental-pattern-search-backward
¶history-incremental-pattern-search-forward
These widgets behave similarly to the corresponding widgets with
no