22 Zsh Modules

22.1 Description

Some optional parts of zsh are in modules, separate from the core of the shell. Each of these modules may be linked in to the shell at build time, or can be dynamically linked while the shell is running if the installation supports this feature. Modules are linked at runtime with the zmodload command, see Shell Builtin Commands.

The modules that are bundled with the zsh distribution are:

zsh/attr

Builtins for manipulating extended attributes (xattr).

zsh/cap

Builtins for manipulating POSIX.1e (POSIX.6) capability (privilege) sets.

zsh/clone

A builtin that can clone a running shell onto another terminal.

zsh/compctl

The compctl builtin for controlling completion.

zsh/complete

The basic completion code.

zsh/complist

Completion listing extensions.

zsh/computil

A module with utility builtins needed for the shell function based completion system.

zsh/curses

curses windowing commands

zsh/datetime

Some date/time commands and parameters.

zsh/db/gdbm

Builtins for managing associative array parameters tied to GDBM databases.

zsh/deltochar

A ZLE function duplicating EMACS’ zap-to-char.

zsh/example

An example of how to write a module.

zsh/files

Some basic file manipulation commands as builtins.

zsh/langinfo

Interface to locale information.

zsh/mapfile

Access to external files via a special associative array.

zsh/mathfunc

Standard scientific functions for use in mathematical evaluations.

zsh/nearcolor

Map colours to the nearest colour in the available palette.

zsh/newuser

Arrange for files for new users to be installed.

zsh/parameter

Access to internal hash tables via special associative arrays.

zsh/pcre

Interface to the PCRE library.

zsh/param/private

Builtins for managing private-scoped parameters in function context.

zsh/regex

Interface to the POSIX regex library.

zsh/sched

A builtin that provides a timed execution facility within the shell.

zsh/net/socket

Manipulation of Unix domain sockets

zsh/stat

A builtin command interface to the stat system call.

zsh/system

A builtin interface to various low-level system features.

zsh/net/tcp

Manipulation of TCP sockets

zsh/termcap

Interface to the termcap database.

zsh/terminfo

Interface to the terminfo database.

zsh/watch

Reporting of login and logout events.

zsh/zftp

A builtin FTP client.

zsh/zle

The Zsh Line Editor, including the bindkey and vared builtins.

zsh/zleparameter

Access to internals of the Zsh Line Editor via parameters.

zsh/zprof

A module allowing profiling for shell functions.

zsh/zpty

A builtin for starting a command in a pseudo-terminal.

zsh/zselect

Block and return when file descriptors are ready.

zsh/zutil

Some utility builtins, e.g. the one for supporting configuration via styles.

22.2 The zsh/attr Module

The zsh/attr module is used for manipulating extended attributes. The -h option causes all commands to operate on symbolic links instead of their targets. The builtins in this module are:

zgetattr [ -h ] filename attribute [ parameter ]

Get the extended attribute attribute from the specified filename. If the optional argument parameter is given, the attribute is set on that parameter instead of being printed to stdout.

zsetattr [ -h ] filename attribute value

Set the extended attribute attribute on the specified filename to value.

zdelattr [ -h ] filename attribute

Remove the extended attribute attribute from the specified filename.

zlistattr [ -h ] filename [ parameter ]

List the extended attributes currently set on the specified filename. If the optional argument parameter is given, the list of attributes is set on that parameter instead of being printed to stdout.

zgetattr and zlistattr allocate memory dynamically. If the attribute or list of attributes grows between the allocation and the call to get them, they return 2. On all other errors, 1 is returned. This allows the calling function to check for this case and retry.

22.3 The zsh/cap Module

The zsh/cap module is used for manipulating POSIX.1e (POSIX.6) capability sets. If the operating system does not support this interface, the builtins defined by this module will do nothing. The builtins in this module are:

cap [ capabilities ]

Change the shell’s process capability sets to the specified capabilities, otherwise display the shell’s current capabilities.

getcap filename ...

This is a built-in implementation of the POSIX standard utility. It displays the capability sets on each specified filename.

setcap capabilities filename ...

This is a built-in implementation of the POSIX standard utility. It sets the capability sets on each specified filename to the specified capabilities.

22.4 The zsh/clone Module

The zsh/clone module makes available one builtin command:

clone tty

Creates a forked instance of the current shell, attached to the specified tty. In the new shell, the PID, PPID and TTY special parameters are changed appropriately. $! is set to zero in the new shell, and to the new shell’s PID in the original shell.

The return status of the builtin is zero in both shells if successful, and non-zero on error.

The target of clone should be an unused terminal, such as an unused virtual console or a virtual terminal created by

xterm -e sh -c 'trap : INT QUIT TSTP; tty;
        while :; do sleep 100000000; done'

Some words of explanation are warranted about this long xterm command line: when doing clone on a pseudo-terminal, some other session ("session" meant as a unix session group, or SID) is already owning the terminal. Hence the cloned zsh cannot acquire the pseudo-terminal as a controlling tty. That means two things:

• the job control signals will go to the sh-started-by-xterm process group (that’s why we disable INT QUIT and TSTP with trap; otherwise the while loop could get suspended or killed)
• the cloned shell will have job control disabled, and the job control keys (control-C, control-\ and control-Z) will not work.

This does not apply when cloning to an unused vc.

Cloning to a used (and unprepared) terminal will result in two processes reading simultaneously from the same terminal, with input bytes going randomly to either process.

clone is mostly useful as a shell built-in replacement for openvt.

22.5 The zsh/compctl Module

The zsh/compctl module makes available two builtin commands. compctl, is the old, deprecated way to control completions for ZLE. See Completion Using compctl. The other builtin command, compcall can be used in user-defined completion widgets, see Completion Widgets.

22.6 The zsh/complete Module

The zsh/complete module makes available several builtin commands which can be used in user-defined completion widgets, see Completion Widgets.

22.7 The zsh/complist Module

The zsh/complist module offers three extensions to completion listings: the ability to highlight matches in such a list, the ability to scroll through long lists and a different style of menu completion.

bindkey -M menuselect '^M' send-break

22.8 The zsh/computil Module

The zsh/computil module adds several builtin commands that are used by some of the completion functions in the completion system based on shell functions (see Completion System ). Except for compquote these builtin commands are very specialised and thus not very interesting when writing your own completion functions. In summary, these builtin commands are:

comparguments

This is used by the _arguments function to do the argument and command line parsing. Like compdescribe it has an option -i to do the parsing and initialize some internal state and various options to access the state information to decide what should be completed.

compdescribe

This is used by the _describe function to build the displays for the matches and to get the strings to add as matches with their options. On the first call one of the options -i or -I should be supplied as the first argument. In the first case, display strings without the descriptions will be generated, in the second case, the string used to separate the matches from their descriptions must be given as the second argument and the descriptions (if any) will be shown. All other arguments are like the definition arguments to _describe itself.

Once compdescribe has been called with either the -i or the -I option, it can be repeatedly called with the -g option and the names of four parameters as its arguments. This will step through the different sets of matches and store the value of compstate[list] in the first scalar, the options for compadd in the second array, the matches in the third array, and the strings to be displayed in the completion listing in the fourth array. The arrays may then be directly given to compadd to register the matches with the completion code.

compfiles

Used by the _path_files function to optimize complex recursive filename generation (globbing). It does three things. With the -p and -P options it builds the glob patterns to use, including the paths already handled and trying to optimize the patterns with respect to the prefix and suffix from the line and the match specification currently used. The -i option does the directory tests for the ignore-parents style and the -r option tests if a component for some of the matches are equal to the string on the line and removes all other matches if that is true.

compgroups

Used by the _tags function to implement the internals of the group-order style. This only takes its arguments as names of completion groups and creates the groups for it (all six types: sorted and unsorted, both without removing duplicates, with removing all duplicates and with removing consecutive duplicates).

compquote [ -p ] names ...

There may be reasons to write completion functions that have to add the matches using the -Q option to compadd and perform quoting themselves. Instead of interpreting the first character of the all_quotes key of the compstate special association and using the q flag for parameter expansions, one can use this builtin command. The arguments are the names of scalar or array parameters and the values of these parameters are quoted as needed for the innermost quoting level. If the -p option is given, quoting is done as if there is some prefix before the values of the parameters, so that a leading equal sign will not be quoted.

The return status is non-zero in case of an error and zero otherwise.

comptags

comptry

These implement the internals of the tags mechanism.

compvalues

Like comparguments, but for the _values function.

22.9 The zsh/curses Module

The zsh/curses module makes available one builtin command and various parameters.

22.10 The zsh/datetime Module

The zsh/datetime module makes available one builtin command:

strftime [ -s scalar | -n ] format [ epochtime [ nanoseconds ] ]

strftime -r [ -q ] [ -s scalar | -n ] format timestring

Output the date in the format specified. With no epochtime, the current system date/time is used; optionally, epochtime may be used to specify the number of seconds since the epoch, and nanoseconds may additionally be used to specify the number of nanoseconds past the second (otherwise that number is assumed to be 0). See strftime(3) for details. The zsh extensions described in Prompt Expansion are also available.

-n

Suppress printing a newline after the formatted string.

-q

Run quietly; suppress printing of all error messages described below. Errors for invalid epochtime values are always printed.

-r

With the option -r (reverse), use format to parse the input string timestring and output the number of seconds since the epoch at which the time occurred. The parsing is implemented by the system function strptime; see strptime(3). This means that zsh format extensions are not available, but for reverse lookup they are not required.

In most implementations of strftime any timezone in the timestring is ignored and the local timezone declared by the TZ environment variable is used; other parameters are set to zero if not present.

If timestring does not match format the command returns status 1 and prints an error message. If timestring matches format but not all characters in timestring were used, the conversion succeeds but also prints an error message.

If either of the system functions strptime or mktime is not available, status 2 is returned and an error message is printed.

-s scalar

Assign the date string (or epoch time in seconds if -r is given) to scalar instead of printing it.

Note that depending on the system’s declared integral time type, strftime may produce incorrect results for epoch times greater than 2147483647 which corresponds to 2038-01-19 03:14:07 +0000.

The zsh/datetime module makes available several parameters; all are readonly:

EPOCHREALTIME

A floating point value representing the number of seconds since the epoch. The notional accuracy is to nanoseconds if the clock_gettime call is available and to microseconds otherwise, but in practice the range of double precision floating point and shell scheduling latencies may be significant effects.

EPOCHSECONDS

An integer value representing the number of seconds since the epoch.

epochtime

An array value containing the number of seconds since the epoch in the first element and the remainder of the time since the epoch in nanoseconds in the second element. To ensure the two elements are consistent the array should be copied or otherwise referenced as a single substitution before the values are used. The following idiom may be used:

for secs nsecs in $epochtime; do
  ...
done

22.11 The zsh/db/gdbm Module

The zsh/db/gdbm module is used to create "tied" associative arrays that interface to database files. If the GDBM interface is not available, the builtins defined by this module will report an error. This module is also intended as a prototype for creating additional database interfaces, so the ztie builtin may move to a more generic module in the future.

The builtins in this module are:

ztie -d db/gdbm -f filename [ -r ] arrayname

Open the GDBM database identified by filename and, if successful, create the associative array arrayname linked to the file. To create a local tied array, the parameter must first be declared, so commands similar to the following would be executed inside a function scope:

local -A sampledb
ztie -d db/gdbm -f sample.gdbm sampledb

The -r option opens the database file for reading only, creating a parameter with the readonly attribute. Without this option, using ‘ztie’ on a file for which the user does not have write permission is an error. If writable, the database is opened synchronously so fields changed in arrayname are immediately written to filename.

Changes to the file modes filename after it has been opened do not alter the state of arrayname, but ‘typeset -r arrayname’ works as expected.

zuntie [ -u ] arrayname ...

Close the GDBM database associated with each arrayname and then unset the parameter. The -u option forces an unset of parameters made readonly with ‘ztie -r’.

This happens automatically if the parameter is explicitly unset or its local scope (function) ends. Note that a readonly parameter may not be explicitly unset, so the only way to unset a global parameter created with ‘ztie -r’ is to use ‘zuntie -u’.

zgdbmpath parametername

Put path to database file assigned to parametername into REPLY scalar.

zgdbm_tied

Array holding names of all tied parameters.

The fields of an associative array tied to GDBM are neither cached nor otherwise stored in memory, they are read from or written to the database on each reference. Thus, for example, the values in a readonly array may be changed by a second writer of the same database file.

22.12 The zsh/deltochar Module

The zsh/deltochar module makes available two ZLE functions:

delete-to-char

Read a character from the keyboard, and delete from the cursor position up to and including the next (or, with repeat count n, the nth) instance of that character. Negative repeat counts mean delete backwards.

zap-to-char

This behaves like delete-to-char, except that the final occurrence of the character itself is not deleted.

22.13 The zsh/example Module

The zsh/example module makes available one builtin command:

example [ -flags ] [ args ... ]

Displays the flags and arguments it is invoked with.

The purpose of the module is to serve as an example of how to write a module.

22.14 The zsh/files Module

The zsh/files module makes available some common commands for file manipulation as builtins; these commands are probably not needed for many normal situations but can be useful in emergency recovery situations with constrained resources. The commands do not implement all features now required by relevant standards committees.

For all commands, a variant beginning zf_ is also available and loaded automatically. Using the features capability of zmodload will let you load only those names you want. Note that it’s possible to load only the builtins with zsh-specific names using the following command:

zmodload -m -F zsh/files b:zf_\*

The commands loaded by default are:

chgrp [ -hRs ] group filename ...

Changes group of files specified. This is equivalent to chown with a user-spec argument of ‘:group’.

chmod [ -Rs ] mode filename ...

Changes mode of files specified.

The specified mode must be in octal.

The -R option causes chmod to recursively descend into directories, changing the mode of all files in the directory after changing the mode of the directory itself.

The -s option is a zsh extension to chmod functionality. It enables paranoid behaviour, intended to avoid security problems involving a chmod being tricked into affecting files other than the ones intended. It will refuse to follow symbolic links, so that (for example) ‘‘chmod 600 /tmp/foo/passwd’’ can’t accidentally chmod /etc/passwd if /tmp/foo happens to be a link to /etc. It will also check where it is after leaving directories, so that a recursive chmod of a deep directory tree can’t end up recursively chmoding /usr as a result of directories being moved up the tree.

chown [ -hRs ] user-spec filename ...

Changes ownership and group of files specified.

The user-spec can be in four forms:

user

change owner to user; do not change group

user::

change owner to user; do not change group

user:

change owner to user; change group to user’s primary group

user:group

change owner to user; change group to group

:group

do not change owner; change group to group

In each case, the ‘:’ may instead be a ‘.’. The rule is that if there is a ‘:’ then the separator is ‘:’, otherwise if there is a ‘.’ then the separator is ‘.’, otherwise there is no separator.

Each of user and group may be either a username (or group name, as appropriate) or a decimal user ID (group ID). Interpretation as a name takes precedence, if there is an all-numeric username (or group name).

If the target is a symbolic link, the -h option causes chown to set the ownership of the link instead of its target.

The -R option causes chown to recursively descend into directories, changing the ownership of all files in the directory after changing the ownership of the directory itself.

The -s option is a zsh extension to chown functionality. It enables paranoid behaviour, intended to avoid security problems involving a chown being tricked into affecting files other than the ones intended. It will refuse to follow symbolic links, so that (for example) ‘‘chown luser /tmp/foo/passwd’’ can’t accidentally chown /etc/passwd if /tmp/foo happens to be a link to /etc. It will also check where it is after leaving directories, so that a recursive chown of a deep directory tree can’t end up recursively chowning /usr as a result of directories being moved up the tree.

ln [ -dfhins ] filename dest

ln [ -dfhins ] filename ... dir

Creates hard (or, with -s, symbolic) links. In the first form, the specified destination is created, as a link to the specified filename. In the second form, each of the filenames is taken in turn, and linked to a pathname in the specified directory that has the same last pathname component.

Normally, ln will not attempt to create hard links to directories. This check can be overridden using the -d option. Typically only the super-user can actually succeed in creating hard links to directories. This does not apply to symbolic links in any case.

By default, existing files cannot be replaced by links. The -i option causes the user to be queried about replacing existing files. The -f option causes existing files to be silently deleted, without querying. -f takes precedence.

The -h and -n options are identical and both exist for compatibility; either one indicates that if the target is a symlink then it should not be dereferenced. Typically this is used in combination with -sf so that if an existing link points to a directory then it will be removed, instead of followed. If this option is used with multiple filenames and the target is a symbolic link pointing to a directory then the result is an error.

mkdir [ -p ] [ -m mode ] dir ...

Creates directories. With the -p option, non-existing parent directories are first created if necessary, and there will be no complaint if the directory already exists. The -m option can be used to specify (in octal) a set of file permissions for the created directories, otherwise mode 777 modified by the current umask (see umask(2)) is used.

mv [ -fi ] filename dest

mv [ -fi ] filename ... dir

Moves files. In the first form, the specified filename is moved to the specified destination. In the second form, each of the filenames is taken in turn, and moved to a pathname in the specified directory that has the same last pathname component.

By default, the user will be queried before replacing any file that the user cannot write to, but writable files will be silently removed. The -i option causes the user to be queried about replacing any existing files. The -f option causes any existing files to be silently deleted, without querying. -f takes precedence.

Note that this mv will not move files across devices. Historical versions of mv, when actual renaming is impossible, fall back on copying and removing files; if this behaviour is desired, use cp and rm manually. This may change in a future version.

rm [ -dfiRrs ] filename ...

Removes files and directories specified.

Normally, rm will not remove directories (except with the -R or -r options). The -d option causes rm to try removing directories with unlink (see unlink(2)), the same method used for files. Typically only the super-user can actually succeed in unlinking directories in this way. -d takes precedence over -R and -r.

By default, the user will be queried before removing any file that the user cannot write to, but writable files will be silently removed. The -i option causes the user to be queried about removing any files. The -f option causes files to be silently deleted, without querying, and suppresses all error indications. -f takes precedence.

The -R and -r options cause rm to recursively descend into directories, deleting all files in the directory before removing the directory with the rmdir system call (see rmdir(2)).

The -s option is a zsh extension to rm functionality. It enables paranoid behaviour, intended to avoid common security problems involving a root-run rm being tricked into removing files other than the ones intended. It will refuse to follow symbolic links, so that (for example) ‘‘rm /tmp/foo/passwd’’ can’t accidentally remove /etc/passwd if /tmp/foo happens to be a link to /etc. It will also check where it is after leaving directories, so that a recursive removal of a deep directory tree can’t end up recursively removing /usr as a result of directories being moved up the tree.

rmdir dir ...

Removes empty directories specified.

sync

Calls the system call of the same name (see sync(2)), which flushes dirty buffers to disk. It might return before the I/O has actually been completed.

22.15 The zsh/langinfo Module

The zsh/langinfo module makes available one parameter:

langinfo

An associative array that maps langinfo elements to their values.

Your implementation may support a number of the following keys:

CODESET, D_T_FMT, D_FMT, T_FMT, RADIXCHAR, THOUSEP, YESEXPR, NOEXPR, CRNCYSTR, ABDAY_{1..7}, DAY_{1..7}, ABMON_{1..12}, MON_{1..12}, T_FMT_AMPM, AM_STR, PM_STR, ERA, ERA_D_FMT, ERA_D_T_FMT, ERA_T_FMT, ALT_DIGITS

22.16 The zsh/mapfile Module

The zsh/mapfile module provides one special associative array parameter of the same name.

mapfile

This associative array takes as keys the names of files; the resulting value is the content of the file. The value is treated identically to any other text coming from a parameter. The value may also be assigned to, in which case the file in question is written (whether or not it originally existed); or an element may be unset, which will delete the file in question. For example, ‘vared 'mapfile[myfile]'’ works as expected, editing the file ‘myfile’.

When the array is accessed as a whole, the keys are the names of files in the current directory, and the values are empty (to save a huge overhead in memory). Thus ${(k)mapfile} has the same effect as the glob operator *(D), since files beginning with a dot are not special. Care must be taken with expressions such as rm ${(k)mapfile}, which will delete every file in the current directory without the usual ‘rm *’ test.

The parameter mapfile may be made read-only; in that case, files referenced may not be written or deleted.

A file may conveniently be read into an array as one line per element with the form ‘array=("${(f@)mapfile[filename]}")’. The double quotes and the ‘@’ are necessary to prevent empty lines from being removed. Note that if the file ends with a newline, the shell will split on the final newline, generating an additional empty field; this can be suppressed by using ‘array=("${(f@)${mapfile[filename]%$'\n'}}")’.

22.17 The zsh/mathfunc Module

The zsh/mathfunc module provides standard mathematical functions for use when evaluating mathematical formulae. The syntax agrees with normal C and FORTRAN conventions, for example,

(( f = sin(0.3) ))

assigns the sine of 0.3 to the parameter f.

Most functions take floating point arguments and return a floating point value. However, any necessary conversions from or to integer type will be performed automatically by the shell. Apart from atan with a second argument and the abs, int and float functions, all functions behave as noted in the manual page for the corresponding C function, except that any arguments out of range for the function in question will be detected by the shell and an error reported.

The following functions take a single floating point argument: acos, acosh, asin, asinh, atan, atanh, cbrt, ceil, cos, cosh, erf, erfc, exp, expm1, fabs, floor, gamma, j0, j1, lgamma, log, log10, log1p, log2, logb, sin, sinh, sqrt, tan, tanh, y0, y1. The atan function can optionally take a second argument, in which case it behaves like the C function atan2. The ilogb function takes a single floating point argument, but returns an integer.

The function signgam takes no arguments, and returns an integer, which is the C variable of the same name, as described in gamma(3). Note that it is therefore only useful immediately after a call to gamma or lgamma. Note also that ‘signgam()’ and ‘signgam’ are distinct expressions.

The functions min, max, and sum are defined not in this module but in the zmathfunc autoloadable function, described in Mathematical Functions.

The following functions take two floating point arguments: copysign, fmod, hypot, nextafter.

The following take an integer first argument and a floating point second argument: jn, yn.

The following take a floating point first argument and an integer second argument: ldexp, scalb.

The function abs does not convert the type of its single argument; it returns the absolute value of either a floating point number or an integer. The functions float and int convert their arguments into a floating point or integer value (by truncation) respectively.

Note that the C pow function is available in ordinary math evaluation as the ‘**’ operator and is not provided here.

The function rand48 is available if your system’s mathematical library has the function erand48(3). It returns a pseudo-random floating point number between 0 and 1. It takes a single string optional argument.

If the argument is not present, the random number seed is initialised by three calls to the rand(3) function — this produces the same random numbers as the next three values of $RANDOM.

If the argument is present, it gives the name of a scalar parameter where the current random number seed will be stored. On the first call, the value must contain at least twelve hexadecimal digits (the remainder of the string is ignored), or the seed will be initialised in the same manner as for a call to rand48 with no argument. Subsequent calls to rand48(param) will then maintain the seed in the parameter param as a string of twelve hexadecimal digits, with no base signifier. The random number sequences for different parameters are completely independent, and are also independent from that used by calls to rand48 with no argument.

For example, consider

print $(( rand48(seed) ))
print $(( rand48() ))
print $(( rand48(seed) ))

Assuming $seed does not exist, it will be initialised by the first call. In the second call, the default seed is initialised; note, however, that because of the properties of rand() there is a correlation between the seeds used for the two initialisations, so for more secure uses, you should generate your own 12-byte seed. The third call returns to the same sequence of random numbers used in the first call, unaffected by the intervening rand48().

22.18 The zsh/nearcolor Module

The zsh/nearcolor module replaces colours specified as hex triplets with the nearest colour in the 88 or 256 colour palettes that are widely used by terminal emulators. By default, 24-bit true colour escape codes are generated when colours are specified using hex triplets. These are not supported by all terminals. The purpose of this module is to make it easier to define colour preferences in a form that can work across a range of terminal emulators.

Aside from the default colour, the ANSI standard for terminal escape codes provides for eight colours. The bright attribute brings this to sixteen. These basic colours are commonly used in terminal applications due to being widely supported. Expanded 88 and 256 colour palettes are also common and, while the first sixteen colours vary somewhat between terminals and configurations, these add a generally consistent and predictable set of colours.

In order to use the zsh/nearcolor module, it only needs to be loaded. Thereafter, whenever a colour is specified using a hex triplet, it will be compared against each of the available colours and the closest will be selected. The first sixteen colours are never matched in this process due to being unpredictable.

It isn’t possible to reliably detect support for true colour in the terminal emulator. It is therefore recommended to be selective in loading the zsh/nearcolor module. For example, the following checks the COLORTERM environment variable:

[[ $COLORTERM = *(24bit|truecolor)* ]] || zmodload zsh/nearcolor

Note that some terminals accept the true color escape codes but map them internally to a more limited palette in a similar manner to the zsh/nearcolor module.

22.19 The zsh/newuser Module

The zsh/newuser module is loaded at boot if it is available, the RCS option is set, and the PRIVILEGED option is not set (all three are true by default). This takes place immediately after commands in the global zshenv file (typically /etc/zshenv), if any, have been executed. If the module is not available it is silently ignored by the shell; the module may safely be removed from $MODULE_PATH by the administrator if it is not required.

On loading, the module tests if any of the start-up files .zshenv, .zprofile, .zshrc or .zlogin exist in the directory given by the environment variable ZDOTDIR, or the user’s home directory if that is not set. The test is not performed and the module halts processing if the shell was in an emulation mode (i.e. had been invoked as some other shell than zsh).

If none of the start-up files were found, the module then looks for the file newuser first in a sitewide directory, usually the parent directory of the site-functions directory, and if that is not found the module searches in a version-specific directory, usually the parent of the functions directory containing version-specific functions. (These directories can be configured when zsh is built using the --enable-site-scriptdir=dir and --enable-scriptdir=dir flags to configure, respectively; the defaults are prefix/share/zsh and prefix/share/zsh/$ZSH_VERSION where the default prefix is /usr/local.)

If the file newuser is found, it is then sourced in the same manner as a start-up file. The file is expected to contain code to install start-up files for the user, however any valid shell code will be executed.

The zsh/newuser module is then unconditionally unloaded.

Note that it is possible to achieve exactly the same effect as the zsh/newuser module by adding code to /etc/zshenv. The module exists simply to allow the shell to make arrangements for new users without the need for intervention by package maintainers and system administrators.

The script supplied with the module invokes the shell function zsh-newuser-install. This may be invoked directly by the user even if the zsh/newuser module is disabled. Note, however, that if the module is not installed the function will not be installed either. The function is documented in User Configuration Functions.

22.20 The zsh/parameter Module

The zsh/parameter module gives access to some of the internal hash tables used by the shell by defining some special parameters.

options

The keys for this associative array are the names of the options that can be set and unset using the setopt and unsetopt builtins. The value of each key is either the string on if the option is currently set, or the string off if the option is unset. Setting a key to one of these strings is like setting or unsetting the option, respectively. Unsetting a key in this array is like setting it to the value off.

commands

This array gives access to the command hash table. The keys are the names of external commands, the values are the pathnames of the files that would be executed when the command would be invoked. Setting a key in this array defines a new entry in this table in the same way as with the hash builtin. Unsetting a key as in ‘unset "commands[foo]"’ removes the entry for the given key from the command hash table.

functions

This associative array maps names of enabled functions to their definitions. Setting a key in it is like defining a function with the name given by the key and the body given by the value. Unsetting a key removes the definition for the function named by the key.

dis_functions

Like functions but for disabled functions.

functions_source

This readonly associative array maps names of enabled functions to the name of the file containing the source of the function.

For an autoloaded function that has already been loaded, or marked for autoload with an absolute path, or that has had its path resolved with ‘functions -r’, this is the file found for autoloading, resolved to an absolute path.

For a function defined within the body of a script or sourced file, this is the name of that file. In this case, this is the exact path originally used to that file, which may be a relative path.

For any other function, including any defined at an interactive prompt or an autoload function whose path has not yet been resolved, this is the empty string. However, the hash element is reported as defined just so long as the function is present: the keys to this hash are the same as those to $functions.

dis_functions_source

Like functions_source but for disabled functions.

builtins

This associative array gives information about the builtin commands currently enabled. The keys are the names of the builtin commands and the values are either ‘undefined’ for builtin commands that will automatically be loaded from a module if invoked or ‘defined’ for builtin commands that are already loaded.

dis_builtins

Like builtins but for disabled builtin commands.

reswords

This array contains the enabled reserved words.

dis_reswords

Like reswords but for disabled reserved words.

patchars

This array contains the enabled pattern characters.

dis_patchars

Like patchars but for disabled pattern characters.

aliases

This maps the names of the regular aliases currently enabled to their expansions.

dis_aliases

Like aliases but for disabled regular aliases.

galiases

Like aliases, but for global aliases.

dis_galiases

Like galiases but for disabled global aliases.

saliases

Like raliases, but for suffix aliases.

dis_saliases

Like saliases but for disabled suffix aliases.

parameters

The keys in this associative array are the names of the parameters currently defined. The values are strings describing the type of the parameter, in the same format used by the t parameter flag, see Parameter Expansion . Setting or unsetting keys in this array is not possible.

modules

An associative array giving information about modules. The keys are the names of the modules loaded, registered to be autoloaded, or aliased. The value says which state the named module is in and is one of the strings ‘loaded’, ‘autoloaded’, or ‘alias:name’, where name is the name the module is aliased to.

Setting or unsetting keys in this array is not possible.

dirstack

A normal array holding the elements of the directory stack. Note that the output of the dirs builtin command includes one more directory, the current working directory.

history

This associative array maps history event numbers to the full history lines. Although it is presented as an associative array, the array of all values (${history[@]}) is guaranteed to be returned in order from most recent to oldest history event, that is, by decreasing history event number.

historywords

A special array containing the words stored in the history. These also appear in most to least recent order.

jobdirs

This associative array maps job numbers to the directories from which the job was started (which may not be the current directory of the job).

The keys of the associative arrays are usually valid job numbers, and these are the values output with, for example, ${(k)jobdirs}. Non-numeric job references may be used when looking up a value; for example, ${jobdirs[%+]} refers to the current job.

See the jobs builtin for how job information is provided in a subshell.

jobtexts

This associative array maps job numbers to the texts of the command lines that were used to start the jobs.

Handling of the keys of the associative array is as described for jobdirs above.

See the jobs builtin for how job information is provided in a subshell.

jobstates

This associative array gives information about the states of the jobs currently known. The keys are the job numbers and the values are strings of the form ‘job-state:mark:pid=state...’. The job-state gives the state the whole job is currently in, one of ‘running’, ‘suspended’, or ‘done’. The mark is ‘+’ for the current job, ‘-’ for the previous job and empty otherwise. This is followed by one ‘:pid=state’ for every process in the job. The pids are, of course, the process IDs and the state describes the state of that process.

Handling of the keys of the associative array is as described for jobdirs above.

See the jobs builtin for how job information is provided in a subshell.

nameddirs

This associative array maps the names of named directories to the pathnames they stand for.

userdirs

This associative array maps user names to the pathnames of their home directories.

usergroups

This associative array maps names of system groups of which the current user is a member to the corresponding group identifiers. The contents are the same as the groups output by the id command.

funcfiletrace

This array contains the absolute line numbers and corresponding file names for the point where the current function, sourced file, or (if EVAL_LINENO is set) eval command was called. The array is of the same length as funcsourcetrace and functrace, but differs from funcsourcetrace in that the line and file are the point of call, not the point of definition, and differs from functrace in that all values are absolute line numbers in files, rather than relative to the start of a function, if any.

funcsourcetrace

This array contains the file names and line numbers of the points where the functions, sourced files, and (if EVAL_LINENO is set) eval commands currently being executed were defined. The line number is the line where the ‘function name’ or ‘name ()’ started. In the case of an autoloaded function the line number is reported as zero. The format of each element is filename:lineno.

For functions autoloaded from a file in native zsh format, where only the body of the function occurs in the file, or for files that have been executed by the source or ‘.’ builtins, the trace information is shown as filename:0, since the entire file is the definition. The source file name is resolved to an absolute path when the function is loaded or the path to it otherwise resolved.

Most users will be interested in the information in the funcfiletrace array instead.

funcstack

This array contains the names of the functions, sourced files, and (if EVAL_LINENO is set) eval commands. currently being executed. The first element is the name of the function using the parameter.

The standard shell array zsh_eval_context can be used to determine the type of shell construct being executed at each depth: note, however, that is in the opposite order, with the most recent item last, and it is more detailed, for example including an entry for toplevel, the main shell code being executed either interactively or from a script, which is not present in $funcstack.

functrace

This array contains the names and line numbers of the callers corresponding to the functions currently being executed. The format of each element is name:lineno. Callers are also shown for sourced files; the caller is the point where the source or ‘.’ command was executed.

22.21 The zsh/pcre Module

The zsh/pcre module makes some commands available as builtins:

pcre_compile [ -aimxs ] PCRE

Compiles a perl-compatible regular expression.

Option -a will force the pattern to be anchored. Option -i will compile a case-insensitive pattern. Option -m will compile a multi-line pattern; that is, ^ and $ will match newlines within the pattern. Option -x will compile an extended pattern, wherein whitespace and # comments are ignored. Option -s makes the dot metacharacter match all characters, including those that indicate newline.

pcre_study

Studies the previously-compiled PCRE which may result in faster matching.

pcre_match [ -v var ] [ -a arr ] [ -n offset ] [ -b ] string

Returns successfully if string matches the previously-compiled PCRE.

Upon successful match, if the expression captures substrings within parentheses, pcre_match will set the array match to those substrings, unless the -a option is given, in which case it will set the array arr. Similarly, the variable MATCH will be set to the entire matched portion of the string, unless the -v option is given, in which case the variable var will be set. No variables are altered if there is no successful match. A -n option starts searching for a match from the byte offset position in string. If the -b option is given, the variable ZPCRE_OP will be set to an offset pair string, representing the byte offset positions of the entire matched portion within the string. For example, a ZPCRE_OP set to "32 45" indicates that the matched portion began on byte offset 32 and ended on byte offset 44. Here, byte offset position 45 is the position directly after the matched portion. Keep in mind that the byte position isn’t necessarily the same as the character position when UTF-8 characters are involved. Consequently, the byte offset positions are only to be relied on in the context of using them for subsequent searches on string, using an offset position as an argument to the -n option. This is mostly used to implement the "find all non-overlapping matches" functionality.

A simple example of "find all non-overlapping matches":

string="The following zip codes: 78884 90210 99513"
pcre_compile -m "\d{5}"
accum=()
pcre_match -b -- $string
while [[ $? -eq 0 ]] do
    b=($=ZPCRE_OP)
    accum+=$MATCH
    pcre_match -b -n $b[2] -- $string
done
print -l $accum

The zsh/pcre module makes available the following test condition:

expr -pcre-match pcre

Matches a string against a perl-compatible regular expression.

For example,

[[ "$text" -pcre-match ^d+$ ]] &&
print text variable contains only "d's".

If the REMATCH_PCRE option is set, the =~ operator is equivalent to -pcre-match, and the NO_CASE_MATCH option may be used. Note that NO_CASE_MATCH never applies to the pcre_match builtin, instead use the -i switch of pcre_compile.

22.22 The zsh/param/private Module

The zsh/param/private module is used to create parameters whose scope is limited to the current function body, and not to other functions called by the current function.

This module provides a single autoloaded builtin:

private [ {+|-}AHUahlmrtux ] [ {+|-}EFLRZi [ n ] ] [ name[=value] ... ]

The private builtin accepts all the same options and arguments as local (Shell Builtin Commands) except for the ‘-T’ option. Tied parameters may not be made private.

The ‘-p’ option is presently a no-op because the state of private parameters cannot reliably be reloaded. This also applies to printing private parameters with ‘typeset -p’.

If used at the top level (outside a function scope), private creates a normal parameter in the same manner as declare or typeset. A warning about this is printed if WARN_CREATE_GLOBAL is set (Options). Used inside a function scope, private creates a local parameter similar to one declared with local, except having special properties noted below.

Special parameters which expose or manipulate internal shell state, such as ARGC, argv, COLUMNS, LINES, UID, EUID, IFS, PROMPT, RANDOM, SECONDS, etc., cannot be made private unless the ‘-h’ option is used to hide the special meaning of the parameter. This may change in the future.

As with other typeset equivalents, private is both a builtin and a reserved word, so arrays may be assigned with parenthesized word list name=(value...) syntax. However, the reserved word ‘private’ is not available until zsh/param/private is loaded, so care must be taken with order of execution and parsing for function definitions which use private. To compensate for this, the module also adds the option ‘-P’ to the ‘local’ builtin to declare private parameters.

For example, this construction fails if zsh/param/private has not yet been loaded when ‘bad_declaration’ is defined:

bad_declaration() {
  zmodload zsh/param/private
  private array=( one two three )
}

This construction works because local is already a keyword, and the module is loaded before the statement is executed:

good_declaration() {
  zmodload zsh/param/private
  local -P array=( one two three )
}

The following is usable in scripts but may have trouble with autoload:

zmodload zsh/param/private
iffy_declaration() {
  private array=( one two three )
}

The private builtin may always be used with scalar assignments and for declarations without assignments.

Parameters declared with private have the following properties:

• Within the function body where it is declared, the parameter behaves as a local, except as noted above for tied or special parameters.
• The type of a parameter declared private cannot be changed in the scope where it was declared, even if the parameter is unset. Thus an array cannot be assigned to a private scalar, etc.
• Within any other function called by the declaring function, the private parameter does NOT hide other parameters of the same name, so for example a global parameter of the same name is visible and may be assigned or unset. This includes calls to anonymous functions, although that may also change in the future. However, the private name may not be created outside the local scope when it was not previously declared.
• An exported private remains in the environment of inner scopes but appears unset for the current shell in those scopes. Generally, exporting private parameters should be avoided.

Note that this differs from the static scope defined by compiled languages derived from C, in that the a new call to the same function creates a new scope, i.e., the parameter is still associated with the call stack rather than with the function definition. It differs from ksh ‘typeset -S’ because the syntax used to define the function has no bearing on whether the parameter scope is respected.

22.23 The zsh/regex Module

The zsh/regex module makes available the following test condition:

expr -regex-match regex

Matches a string against a POSIX extended regular expression. On successful match, matched portion of the string will normally be placed in the MATCH variable. If there are any capturing parentheses within the regex, then the match array variable will contain those. If the match is not successful, then the variables will not be altered.

For example,

[[ alphabetical -regex-match ^a([^a]+)a([^a]+)a ]] &&
print -l $MATCH X $match

If the option REMATCH_PCRE is not set, then the =~ operator will automatically load this module as needed and will invoke the -regex-match operator.

If BASH_REMATCH is set, then the array BASH_REMATCH will be set instead of MATCH and match.

Note that the zsh/regex module logic relies on the host system. The same expr and regex pair could produce different results on different platforms if a regex with non-standard syntax is given.

For example, no syntax for matching a word boundary is defined in the POSIX extended regular expression standard. GNU libc and BSD libc both provide such syntaxes as extensions (\b and [[:<:]]/[[:>:]] respectively), but neither of these syntaxes is supported by both of these implementations.

Refer to the regcomp(3) and re_format(7) manual pages on your system for locally-supported syntax.

22.24 The zsh/sched Module

The zsh/sched module makes available one builtin command and one parameter.

sched [-o] [+]hh:mm[:ss] command ...

sched [-o] [+]seconds command ...

sched [ -item ]

Make an entry in the scheduled list of commands to execute. The time may be specified in either absolute or relative time, and either as hours, minutes and (optionally) seconds separated by a colon, or seconds alone. An absolute number of seconds indicates the time since the epoch (1970/01/01 00:00); this is useful in combination with the features in the zsh/datetime module, see The zsh/datetime Module.

With no arguments, prints the list of scheduled commands. If the scheduled command has the -o flag set, this is shown at the start of the command.

With the argument ‘-item’, removes the given item from the list. The numbering of the list is continuous and entries are in time order, so the numbering can change when entries are added or deleted.

Commands are executed either immediately before a prompt, or while the shell’s line editor is waiting for input. In the latter case it is useful to be able to produce output that does not interfere with the line being edited. Providing the option -o causes the shell to clear the command line before the event and redraw it afterwards. This should be used with any scheduled event that produces visible output to the terminal; it is not needed, for example, with output that updates a terminal emulator’s title bar.

To effect changes to the editor buffer when an event executes, use the ‘zle’ command with no arguments to test whether the editor is active, and if it is, then use ‘zle widget’ to access the editor via the named widget.

The sched builtin 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/sched b:sched’.

zsh_scheduled_events

A readonly array corresponding to the events scheduled by the sched builtin. The indices of the array correspond to the numbers shown when sched is run with no arguments (provided that the KSH_ARRAYS option is not set). The value of the array consists of the scheduled time in seconds since the epoch (see The zsh/datetime Module for facilities for using this number), followed by a colon, followed by any options (which may be empty but will be preceded by a ‘-’ otherwise), followed by a colon, followed by the command to be executed.

The sched builtin should be used for manipulating the events. Note that this will have an immediate effect on the contents of the array, so that indices may become invalid.

22.25 The zsh/net/socket Module

The zsh/net/socket module makes available one builtin command:

zsocket [ -altv ] [ -d fd ] [ args ]

zsocket is implemented as a builtin to allow full use of shell command line editing, file I/O, and job control mechanisms.

22.26 The zsh/stat Module

The zsh/stat module makes available one builtin command under two possible names:

zstat [ -gnNolLtTrs ] [ -f fd ] [ -H hash ] [ -A array ] [ -F fmt ]

      [ +element ] [ file ... ]

stat ...

The command acts as a front end to the stat system call (see stat(2)). The same command is provided with two names; as the name stat is often used by an external command it is recommended that only the zstat form of the command is used. This can be arranged by loading the module with the command ‘zmodload -F zsh/stat b:zstat’.

If the stat call fails, the appropriate system error message printed and status 1 is returned. The fields of struct stat give information about the files provided as arguments to the command. In addition to those available from the stat call, an extra element ‘link’ is provided. These elements are:

device

The number of the device on which the file resides.

inode

The unique number of the file on this device (‘inode’ number).

mode

The mode of the file; that is, the file’s type and access permissions. With the -s option, this will be returned as a string corresponding to the first column in the display of the ls -l command.

nlink

The number of hard links to the file.

uid

The user ID of the owner of the file. With the -s option, this is displayed as a user name.

gid

The group ID of the file. With the -s option, this is displayed as a group name.

rdev

The raw device number. This is only useful for special devices.

size

The size of the file in bytes.

atime

mtime

ctime

The last access, modification and inode change times of the file, respectively, as the number of seconds since midnight GMT on 1st January, 1970. With the -s option, these are printed as strings for the local time zone; the format can be altered with the -F option, and with the -g option the times are in GMT.

blksize

The number of bytes in one allocation block on the device on which the file resides.

block

The number of disk blocks used by the file.

link

If the file is a link and the -L option is in effect, this contains the name of the file linked to, otherwise it is empty. Note that if this element is selected (‘‘zstat +link’’) then the -L option is automatically used.

A particular element may be selected by including its name preceded by a ‘+’ in the option list; only one element is allowed. The element may be shortened to any unique set of leading characters. Otherwise, all elements will be shown for all files.

Options:

-A array

Instead of displaying the results on standard output, assign them to an array, one struct stat element per array element for each file in order. In this case neither the name of the element nor the name of the files appears in array unless the -t or -n options were given, respectively. If -t is given, the element name appears as a prefix to the appropriate array element; if -n is given, the file name appears as a separate array element preceding all the others. Other formatting options are respected.

-H hash

Similar to -A, but instead assign the values to hash. The keys are the elements listed above. If the -n option is provided then the name of the file is included in the hash with key name.

-f fd

Use the file on file descriptor fd instead of named files; no list of file names is allowed in this case.

-F fmt

Supplies a strftime (see strftime(3)) string for the formatting of the time elements. The format string supports all of the zsh extensions described in Prompt Expansion. In particular, -F %s.%N can be used to show timestamps with nanosecond precision if supported by the system. The -s option is implied.

-g

Show the time elements in the GMT time zone. The -s option is implied.

-l

List the names of the type elements (to standard output or an array as appropriate) and return immediately; arguments, and options other than -A, are ignored.

-L

Perform an lstat (see lstat(2)) rather than a stat system call. In this case, if the file is a link, information about the link itself rather than the target file is returned. This option is required to make the link element useful. It’s important to note that this is the exact opposite from ls(1), etc.

-n

Always show the names of files. Usually these are only shown when output is to standard output and there is more than one file in the list.

-N

Never show the names of files.

-o

If a raw file mode is printed, show it in octal, which is more useful for human consumption than the default of decimal. A leading zero will be printed in this case. Note that this does not affect whether a raw or formatted file mode is shown, which is controlled by the -r and -s options, nor whether a mode is shown at all.

-r

Print raw data (the default format) alongside string data (the -s format); the string data appears in parentheses after the raw data.

-s

Print mode, uid, gid and the three time elements as strings instead of numbers. In each case the format is like that of ls -l.

-t

Always show the type names for the elements of struct stat. Usually these are only shown when output is to standard output and no individual element has been selected.

-T

Never show the type names of the struct stat elements.

22.27 The zsh/system Module

The zsh/system module makes available various builtin commands and parameters.

22.28 The zsh/net/tcp Module

The zsh/net/tcp module makes available one builtin command:

ztcp [ -acflLtv ] [ -d fd ] [ args ]

ztcp is implemented as a builtin to allow full use of shell command line editing, file I/O, and job control mechanisms.

If ztcp is run with no options, it will output the contents of its session table.

If it is run with only the option -L, it will output the contents of the session table in a format suitable for automatic parsing. The option is ignored if given with a command to open or close a session. The output consists of a set of lines, one per session, each containing the following elements separated by spaces:

File descriptor

The file descriptor in use for the connection. For normal inbound (I) and outbound (O) connections this may be read and written by the usual shell mechanisms. However, it should only be close with ‘ztcp -c’.

Connection type

A letter indicating how the session was created:

Z

A session created with the zftp command.

L

A connection opened for listening with ‘ztcp -l’.

I

An inbound connection accepted with ‘ztcp -a’.

O

An outbound connection created with ‘ztcp host ...’.

The local host

This is usually set to an all-zero IP address as the address of the localhost is irrelevant.

The local port

This is likely to be zero unless the connection is for listening.

The remote host

This is the fully qualified domain name of the peer, if available, else an IP address. It is an all-zero IP address for a session opened for listening.

The remote port

This is zero for a connection opened for listening.

zmodload zsh/net/tcp
ztcp -l 5123
listenfd=$REPLY
ztcp -a $listenfd
fd=$REPLY

zmodload zsh/net/tcp
ztcp host1 5123
fd=$REPLY

print This is a message >&$fd

read -r line <&$fd; print -r - $line

ztcp -c $listenfd
ztcp -c $fd

ztcp -c $fd

22.29 The zsh/termcap Module

The zsh/termcap module makes available one builtin command:

echotc cap [ arg ... ]

Output the termcap value corresponding to the capability cap, with optional arguments.

The zsh/termcap module makes available one parameter:

termcap

An associative array that maps termcap capability codes to their values.

22.30 The zsh/terminfo Module

The zsh/terminfo module makes available one builtin command:

echoti cap [ arg ]

Output the terminfo value corresponding to the capability cap, instantiated with arg if applicable.

The zsh/terminfo module makes available one parameter:

terminfo

An associative array that maps terminfo capability names to their values.

22.31 The zsh/watch Module

The zsh/watch module can be used to report when specific users log in or out. This is controlled via the following parameters.

LOGCHECK

The interval in seconds between checks for login/logout activity using the watch parameter.

watch <S> <Z> (WATCH <S>)

An array (colon-separated list) of login/logout events to report.

If it contains the single word ‘all’, then all login/logout events are reported. If it contains the single word ‘notme’, then all events are reported as with ‘all’ except $USERNAME.

An entry in this list may consist of a username, an ‘@’ followed by a remote hostname, and a ‘%’ followed by a line (tty). Any of these may be a pattern (be sure to quote this during the assignment to watch so that it does not immediately perform file generation); the setting of the EXTENDED_GLOB option is respected. Any or all of these components may be present in an entry; if a login/logout event matches all of them, it is reported.

For example, with the EXTENDED_GLOB option set, the following:

watch=('^(pws|barts)')

causes reports for activity associated with any user other than pws or barts.

WATCHFMT

The format of login/logout reports if the watch parameter is set. Default is ‘%n has %a %l from %m’. Recognizes the following escape sequences:

%n

The name of the user that logged in/out.

%a

The observed action, i.e. "logged on" or "logged off".

%l

The line (tty) the user is logged in on.

%M

The full hostname of the remote host.

%m

The hostname up to the first ‘.’. If only the IP address is available or the utmp field contains the name of an X-windows display, the whole name is printed.

NOTE: The ‘%m’ and ‘%M’ escapes will work only if there is a host name field in the utmp on your machine. Otherwise they are treated as ordinary strings.

%F{color} (%f)

Start (stop) using a different foreground color.

%K{color} (%k)

Start (stop) using a different background color.

%S (%s)

Start (stop) standout mode.

%U (%u)

Start (stop) underline mode.

%B (%b)

Start (stop) boldface mode.

%t

%@

The time, in 12-hour, am/pm format.

%T

The time, in 24-hour format.

%w

The date in ‘day-dd’ format.

%W

The date in ‘mm/dd/yy’ format.

%D

The date in ‘yy-mm-dd’ format.

%D{string}

The date formatted as string using the strftime function, with zsh extensions as described by Prompt Expansion.

%(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. Both the separator and the right parenthesis may be escaped with a backslash. Ternary expressions may be nested.

The test character x may be any one of ‘l’, ‘n’, ‘m’ or ‘M’, which indicate a ‘true’ result if the corresponding escape sequence would return a non-empty value; or it may be ‘a’, which indicates a ‘true’ result if the watched user has logged in, or ‘false’ if he has logged out. Other characters evaluate to neither true nor false; the entire expression is omitted in this case.

If the result is ‘true’, then the true-text is formatted according to the rules above and printed, and the false-text is skipped. If ‘false’, the true-text is skipped and the false-text is formatted and printed. Either or both of the branches may be empty, but both separators must be present in any case.

Furthermore, the zsh/watch module makes available one builtin command:

log

List all users currently logged in who are affected by the current setting of the watch parameter.

22.32 The zsh/zftp Module

The zsh/zftp module makes available one builtin command:

zftp subcommand [ args ]

The zsh/zftp module is a client for FTP (file transfer protocol). It is implemented as a builtin to allow full use of shell command line editing, file I/O, and job control mechanisms. Often, users will access it via shell functions providing a more powerful interface; a set is provided with the zsh distribution and is described in Zftp Function System. However, the zftp command is entirely usable in its own right.

All commands consist of the command name zftp followed by the name of a subcommand. These are listed below. The return status of each subcommand is supposed to reflect the success or failure of the remote operation. See a description of the variable ZFTP_VERBOSE for more information on how responses from the server may be printed.

22.33 The zsh/zle Module

The zsh/zle module contains the Zsh Line Editor. See Zsh Line Editor.

22.34 The zsh/zleparameter Module

The zsh/zleparameter module defines two special parameters that can be used to access internal information of the Zsh Line Editor (see Zsh Line Editor).

keymaps

This array contains the names of the keymaps currently defined.

widgets

This associative array contains one entry per widget. The name of the widget is the key and the value gives information about the widget. It is either the string ‘builtin’ for builtin widgets, a string of the form ‘user:name’ for user-defined widgets, where name is the name of the shell function implementing the widget, a string of the form ‘completion:type:name’ for completion widgets, or a null value if the widget is not yet fully defined. In the penultimate case, type is the name of the builtin widget the completion widget imitates in its behavior and name is the name of the shell function implementing the completion widget.

22.35 The zsh/zprof Module

When loaded, the zsh/zprof causes shell functions to be profiled. The profiling results can be obtained with the zprof builtin command made available by this module. There is no way to turn profiling off other than unloading the module.

zprof [ -c ]

Without the -c option, zprof lists profiling results to standard output. The format is comparable to that of commands like gprof.

At the top there is a summary listing all functions that were called at least once. This summary is sorted in decreasing order of the amount of time spent in each. The lines contain the number of the function in order, which is used in other parts of the list in suffixes of the form ‘[num]’, then the number of calls made to the function. The next three columns list the time in milliseconds spent in the function and its descendants, the average time in milliseconds spent in the function and its descendants per call and the percentage of time spent in all shell functions used in this function and its descendants. The following three columns give the same information, but counting only the time spent in the function itself. The final column shows the name of the function.

After the summary, detailed information about every function that was invoked is listed, sorted in decreasing order of the amount of time spent in each function and its descendants. Each of these entries consists of descriptions for the functions that called the function described, the function itself, and the functions that were called from it. The description for the function itself has the same format as in the summary (and shows the same information). The other lines don’t show the number of the function at the beginning and have their function named indented to make it easier to distinguish the line showing the function described in the section from the surrounding lines.

The information shown in this case is almost the same as in the summary, but only refers to the call hierarchy being displayed. For example, for a calling function the column showing the total running time lists the time spent in the described function and its descendants only for the times when it was called from that particular calling function. Likewise, for a called function, this columns lists the total time spent in the called function and its descendants only for the times when it was called from the function described.

Also in this case, the column showing the number of calls to a function also shows a slash and then the total number of invocations made to the called function.

As long as the zsh/zprof module is loaded, profiling will be done and multiple invocations of the zprof builtin command will show the times and numbers of calls since the module was loaded. With the -c option, the zprof builtin command will reset its internal counters and will not show the listing.

22.36 The zsh/zpty Module

The zsh/zpty module offers one builtin:

zpty [ -e ] [ -b ] name [ arg ... ]

The arguments following name are concatenated with spaces between, then executed as a command, as if passed to the eval builtin. The command runs under a newly assigned pseudo-terminal; this is useful for running commands non-interactively which expect an interactive environment. The name is not part of the command, but is used to refer to this command in later calls to zpty.

With the -e option, the pseudo-terminal is set up so that input characters are echoed.

With the -b option, input to and output from the pseudo-terminal are made non-blocking.

The shell parameter REPLY is set to the file descriptor assigned to the master side of the pseudo-terminal. This allows the terminal to be monitored with ZLE descriptor handlers (see Zle Builtins) or manipulated with sysread and syswrite (see The zsh/system Module). Warning: Use of sysread and syswrite is not recommended; use zpty -r and zpty -w unless you know exactly what you are doing.

zpty -d [ name ... ]

The second form, with the -d option, is used to delete commands previously started, by supplying a list of their names. If no name is given, all commands are deleted. Deleting a command causes the HUP signal to be sent to the corresponding process.

zpty -w [ -n ] name [ string ... ]

The -w option can be used to send the to command name the given strings as input (separated by spaces). If the -n option is not given, a newline is added at the end.

If no string is provided, the standard input is copied to the pseudo-terminal; this may stop before copying the full input if the pseudo-terminal is non-blocking. The exact input is always copied: the -n option is not applied.

Note that the command under the pseudo-terminal sees this input as if it were typed, so beware when sending special tty driver characters such as word-erase, line-kill, and end-of-file.

zpty -r [ -mt ] name [ param [ pattern ] ]

The -r option can be used to read the output of the command name. With only a name argument, the output read is copied to the standard output. Unless the pseudo-terminal is non-blocking, copying continues until the command under the pseudo-terminal exits; when non-blocking, only as much output as is immediately available is copied. The return status is zero if any output is copied.

When also given a param argument, at most one line is read and stored in the parameter named param. Less than a full line may be read if the pseudo-terminal is non-blocking. The return status is zero if at least one character is stored in param.

If a pattern is given as well, output is read until the whole string read matches the pattern, even in the non-blocking case. The return status is zero if the string read matches the pattern, or if the command has exited but at least one character could still be read. If the option -m is present, the return status is zero only if the pattern matches. As of this writing, a maximum of one megabyte of output can be consumed this way; if a full megabyte is read without matching the pattern, the return status is non-zero.

In all cases, the return status is non-zero if nothing could be read, and is 2 if this is because the command has finished.

If the -r option is combined with the -t option, zpty tests whether output is available before trying to read. If no output is available, zpty immediately returns the status 1. When used with a pattern, the behaviour on a failed poll is similar to when the command has exited: the return value is zero if at least one character could still be read even if the pattern failed to match.

zpty -t name

The -t option without the -r option can be used to test whether the command name is still running. It returns a zero status if the command is running and a non-zero value otherwise.

zpty [ -L ]

The last form, without any arguments, is used to list the commands currently defined. If the -L option is given, this is done in the form of calls to the zpty builtin.

22.37 The zsh/zselect Module

The zsh/zselect module makes available one builtin command:

zselect [ -rwe ] [ -t timeout ] [ -a array ] [ -A assoc ] [ fd ... ]

The zselect builtin is a front-end to the ‘select’ system call, which blocks until a file descriptor is ready for reading or writing, or has an error condition, with an optional timeout. If this is not available on your system, the command prints an error message and returns status 2 (normal errors return status 1). For more information, see your system’s documentation for select(3). Note there is no connection with the shell builtin of the same name.

Arguments and options may be intermingled in any order. Non-option arguments are file descriptors, which must be decimal integers. By default, file descriptors are to be tested for reading, i.e. zselect will return when data is available to be read from the file descriptor, or more precisely, when a read operation from the file descriptor will not block. After a -r, -w and -e, the given file descriptors are to be tested for reading, writing, or error conditions. These options and an arbitrary list of file descriptors may be given in any order.

(The presence of an ‘error condition’ is not well defined in the documentation for many implementations of the select system call. According to recent versions of the POSIX specification, it is really an exception condition, of which the only standard example is out-of-band data received on a socket. So zsh users are unlikely to find the -e option useful.)

The option ‘-t timeout’ specifies a timeout in hundredths of a second. This may be zero, in which case the file descriptors will simply be polled and zselect will return immediately. It is possible to call zselect with no file descriptors and a non-zero timeout for use as a finer-grained replacement for ‘sleep’; note, however, the return status is always 1 for a timeout.

The option ‘-a array’ indicates that array should be set to indicate the file descriptor(s) which are ready. If the option is not given, the array reply will be used for this purpose. The array will contain a string similar to the arguments for zselect. For example,

zselect -t 0 -r 0 -w 1

might return immediately with status 0 and $reply containing ‘-r 0 -w 1’ to show that both file descriptors are ready for the requested operations.

The option ‘-A assoc’ indicates that the associative array assoc should be set to indicate the file descriptor(s) which are ready. This option overrides the option -a, nor will reply be modified. The keys of assoc are the file descriptors, and the corresponding values are any of the characters ‘rwe’ to indicate the condition.

The command returns status 0 if some file descriptors are ready for reading. If the operation timed out, or a timeout of 0 was given and no file descriptors were ready, or there was an error, it returns status 1 and the array will not be set (nor modified in any way). If there was an error in the select operation the appropriate error message is printed.

22.38 The zsh/zutil Module

The zsh/zutil module only adds some builtins:

zstyle [ -L [ metapattern [ style ] ] ]

zstyle [ -e | - | -- ] pattern style string ...

zstyle -d [ pattern [ style ... ] ]

zstyle -g name [ pattern [ style ] ]

zstyle -{a|b|s} context style name [ sep ]

zstyle -{T|t} context style [ string ... ]

zstyle -m context style pattern

This builtin command is used to define and lookup styles. Styles are pairs of names and values, where the values consist of any number of strings. They are stored together with patterns and lookup is done by giving a string, called the ‘context’, which is matched against the patterns. The definition stored for the most specific pattern that matches will be returned.

A pattern is considered to be more specific than another if it contains more components (substrings separated by colons) or if the patterns for the components are more specific, where simple strings are considered to be more specific than patterns and complex patterns are considered to be more specific than the pattern ‘*’. A ‘*’ in the pattern will match zero or more characters in the context; colons are not treated specially in this regard. If two patterns are equally specific, the tie is broken in favour of the pattern that was defined first.

Example

For example, a fictional ‘weather’ plugin might state in its documentation that it looks up the preferred-precipitation style under the ‘:weather:continent:day-of-the-week:phase-of-the-moon’ context. According to this, you might set the following in your zshrc:

zstyle ':weather:europe:*' preferred-precipitation rain
zstyle ':weather:*:Sunday:*' preferred-precipitation snow

Then the plugin would run under the hood a command such as

zstyle -s ":weather:${continent}:${day_of_week}:${moon_phase}" preferred-precipitation REPLY

in order to retrieve your preference into the scalar variable $REPLY. On Sundays $REPLY would be set to ‘snow’; in Europe it would be set to ‘rain’; and on Sundays in Europe it would be set to ‘snow’ again, because the patterns ‘:weather:europe:*’ and ‘:weather:*:Sunday:*’ both match the context argument to zstyle -s, are equally specific, and the latter is more specific (because it has more colon-separated components).

Usage

The forms that operate on patterns are the following.

zstyle [ -L [ metapattern [ style ] ] ]

Without arguments, lists style definitions. Styles are shown in alphabetic order and patterns are shown in the order zstyle will test them.

If the -L option is given, listing is done in the form of calls to zstyle. The optional first argument, metapattern, is a pattern which will be matched against the string supplied as pattern when the style was defined. Note: this means, for example, ‘zstyle -L ":completion:*"’ will match any supplied pattern beginning ‘:completion:’, not just ":completion:*": use ':completion:\*' to match that. The optional second argument limits the output to a specific style (not a pattern). -L is not compatible with any other options.

zstyle [ - | -- | -e ] pattern style string ... ¶

Defines the given style for the pattern with the strings as the value. If the -e option is given, the strings will be concatenated (separated by spaces) and the resulting string will be evaluated (in the same way as it is done by the eval builtin command) when the style is looked up. In this case the parameter ‘reply’ must be assigned to set the strings returned after the evaluation. Before evaluating the value, reply is unset, and if it is still unset after the evaluation, the style is treated as if it were not set.

zstyle -d [ pattern [ style ... ] ]

Delete style definitions. Without arguments all definitions are deleted, with a pattern all definitions for that pattern are deleted and if any styles are given, then only those styles are deleted for the pattern.

zstyle -g name [ pattern [ style ] ]

Retrieve a style definition. The name is used as the name of an array in which the results are stored. Without any further arguments, all patterns defined are returned. With a pattern the styles defined for that pattern are returned and with both a pattern and a style, the value strings of that combination is returned.

The other forms can be used to look up or test styles for a given context.

zstyle -s context style name [ sep ]

The parameter name is set to the value of the style interpreted as a string. If the value contains several strings they are concatenated with spaces (or with the sep string if that is given) between them.

Return 0 if the style is set, 1 otherwise.

zstyle -b context style name

The value is stored in name as a boolean, i.e. as the string ‘yes’ if the value has only one string and that string is equal to one of ‘yes’, ‘true’, ‘on’, or ‘1’. If the value is any other string or has more than one string, the parameter is set to ‘no’.

Return 0 if name is set to ‘yes’, 1 otherwise.

zstyle -a context style name

The value is stored in name as an array. If name is declared as an associative array, the first, third, etc. strings are used as the keys and the other strings are used as the values.

Return 0 if the style is set, 1 otherwise.

zstyle -t context style [ string ... ]

zstyle -T context style [ string ... ]

Test the value of a style, i.e. the -t option only returns a status (sets $?). Without any string the return status is zero if the style is defined for at least one matching pattern, has only one string in its value, and that is equal to one of ‘true’, ‘yes’, ‘on’ or ‘1’. If any strings are given the status is zero if and only if at least one of the strings is equal to at least one of the strings in the value. If the style is defined but doesn’t match, the return status is 1. If the style is not defined, the status is 2.

The -T option tests the values of the style like -t, but it returns status zero (rather than 2) if the style is not defined for any matching pattern.

zstyle -m context style pattern

Match a value. Returns status zero if the pattern matches at least one of the strings in the value.

zformat -f param format spec ...

zformat -F param format spec ...

zformat -a array sep spec ...

This builtin provides different forms of formatting. The first form is selected with the -f option. In this case the format string will be modified by replacing sequences starting with a percent sign in it with strings from the specs. Each spec should be of the form ‘char:string’ which will cause every appearance of the sequence ‘%char’ in format to be replaced by the string. The ‘%’ sequence may also contain optional minimum and maximum field width specifications between the ‘%’ and the ‘char’ in the form ‘%min.maxc’, i.e. the minimum field width is given first and if the maximum field width is used, it has to be preceded by a dot. Specifying a minimum field width makes the result be padded with spaces to the right if the string is shorter than the requested width. Padding to the left can be achieved by giving a negative minimum field width. If a maximum field width is specified, the string will be truncated after that many characters. After all ‘%’ sequences for the given specs have been processed, the resulting string is stored in the parameter param.

The %-escapes also understand ternary expressions in the form used by prompts. The % is followed by a ‘(’ and then an ordinary format specifier character as described above. There may be a set of digits either before or after the ‘(’; these specify a test number, which defaults to zero. Negative numbers are also allowed. An arbitrary delimiter character follows the format specifier, which is followed by a piece of ‘true’ text, the delimiter character again, a piece of ‘false’ text, and a closing parenthesis. The complete expression (without the digits) thus looks like ‘%(X.text1.text2)’, except that the ‘.’ character is arbitrary. The value given for the format specifier in the char:string expressions is evaluated as a mathematical expression, and compared with the test number. If they are the same, text1 is output, else text2 is output. A parenthesis may be escaped in text2 as %). Either of text1 or text2 may contain nested %-escapes.

For example:

zformat -f REPLY "The answer is '%3(c.yes.no)'." c:3

outputs "The answer is ’yes’." to REPLY since the value for the format specifier c is 3, agreeing with the digit argument to the ternary expression.

With -F instead of -f, ternary expressions choose between the ‘true’ or ‘false’ text on the basis of whether the format specifier is present and non-empty. A test number indicates a minimum width for the value given in the format specifier. Negative numbers reverse this, so the test is for whether the value exceeds a maximum width.

The form, using the -a option, can be used for aligning strings. Here, the specs are of the form ‘left:right’ where ‘left’ and ‘right’ are arbitrary strings. These strings are modified by replacing the colons by the sep string and padding the left strings with spaces to the right so that the sep strings in the result (and hence the right strings after them) are all aligned if the strings are printed below each other. All strings without a colon are left unchanged and all strings with an empty right string have the trailing colon removed. In both cases the lengths of the strings are not used to determine how the other strings are to be aligned. A colon in the left string can be escaped with a backslash. The resulting strings are stored in the array.

zregexparse

This implements some internals of the _regex_arguments function.

zparseopts [ -D -E -F -K -M ] [ -a array ] [ -A assoc ] [ - ] spec ...

This builtin simplifies the parsing of options in positional parameters, i.e. the set of arguments given by $*. Each spec describes one option and must be of the form ‘opt[=array]’. If an option described by opt is found in the positional parameters it is copied into the array specified with the -a option; if the optional ‘=array’ is given, it is instead copied into that array, which should be declared as a normal array and never as an associative array.

Note that it is an error to give any spec without an ‘=array’ unless one of the -a or -A options is used.

Unless the -E option is given, parsing stops at the first string that isn’t described by one of the specs. Even with -E, parsing always stops at a positional parameter equal to ‘-’ or ‘--’. See also -F.

The opt description must be one of the following. Any of the special characters can appear in the option name provided it is preceded by a backslash.

name

name+

The name is the name of the option without the leading ‘-’. To specify a GNU-style long option, one of the usual two leading ‘-’ must be included in name; for example, a ‘--file’ option is represented by a name of ‘-file’.

If a ‘+’ appears after name, the option is appended to array each time it is found in the positional parameters; without the ‘+’ only the last occurrence of the option is preserved.

If one of these forms is used, the option takes no argument, so parsing stops if the next positional parameter does not also begin with ‘-’ (unless the -E option is used).

name:

name:-

name::

If one or two colons are given, the option takes an argument; with one colon, the argument is mandatory and with two colons it is optional. The argument is appended to the array after the option itself.

An optional argument is put into the same array element as the option name (note that this makes empty strings as arguments indistinguishable). A mandatory argument is added as a separate element unless the ‘:-’ form is used, in which case the argument is put into the same element.

A ‘+’ as described above may appear between the name and the first colon.

In all cases, option-arguments must appear either immediately following the option in the same positional parameter or in the next one. Even an optional argument may appear in the next parameter, unless it begins with a ‘-’. There is no special handling of ‘=’ as with GNU-style argument parsers; given the spec ‘-foo:’, the positional parameter ‘--foo=bar’ is parsed as ‘--foo’ with an argument of ‘=bar’.

When the names of two options that take no arguments overlap, the longest one wins, so that parsing for the specs ‘-foo -foobar’ (for example) is unambiguous. However, due to the aforementioned handling of option-arguments, ambiguities may arise when at least one overlapping spec takes an argument, as in ‘-foo: -foobar’. In that case, the last matching spec wins.

The options of zparseopts itself cannot be stacked because, for example, the stack ‘-DEK’ is indistinguishable from a spec for the GNU-style long option ‘--DEK’. The options of zparseopts itself are:

-a array

As described above, this names the default array in which to store the recognised options.

-A assoc

If this is given, the options and their values are also put into an associative array with the option names as keys and the arguments (if any) as the values.

-D

If this option is given, all options found are removed from the positional parameters of the calling shell or shell function, up to but not including any not described by the specs. If the first such parameter is ‘-’ or ‘--’, it is removed as well. This is similar to using the shift builtin.

-E

This changes the parsing rules to not stop at the first string that isn’t described by one of the specs. It can be used to test for or (if used together with -D) extract options and their arguments, ignoring all other options and arguments that may be in the positional parameters. As indicated above, parsing still stops at the first ‘-’ or ‘--’ not described by a spec, but it is not removed when used with -D.

-F

If this option is given, zparseopts immediately stops at the first option-like parameter not described by one of the specs, prints an error message, and returns status 1. Removal (-D) and extraction (-E) are not performed, and option arrays are not updated. This provides basic validation for the given options.

Note that the appearance in the positional parameters of an option without its required argument always aborts parsing and returns an error as described above regardless of whether this option is used.

-K

With this option, the arrays specified with the -a option and with the ‘=array’ forms are kept unchanged when none of the specs for them is used. Otherwise the entire array is replaced when any of the specs is used. Individual elements of associative arrays specified with the -A option are preserved by -K. This allows assignment of default values to arrays before calling zparseopts.

-M

This changes the assignment rules to implement a map among equivalent option names. If any spec uses the ‘=array’ form, the string array is interpreted as the name of another spec, which is used to choose where to store the values. If no other spec is found, the values are stored as usual. This changes only the way the values are stored, not the way $* is parsed, so results may be unpredictable if the ‘name+’ specifier is used inconsistently.

For example,

set -- -a -bx -c y -cz baz -cend
zparseopts a=foo b:=bar c+:=bar

will have the effect of

foo=(-a)
bar=(-b x -c y -c z)

The arguments from ‘baz’ on will not be used.

As an example for the -E option, consider:

set -- -a x -b y -c z arg1 arg2
zparseopts -E -D b:=bar

will have the effect of

bar=(-b y)
set -- -a x -c z arg1 arg2

I.e., the option -b and its arguments are taken from the positional parameters and put into the array bar.

The -M option can be used like this:

set -- -a -bx -c y -cz baz -cend
zparseopts -A bar -M a=foo b+: c:=b

to have the effect of

foo=(-a)
bar=(-a '' -b xyz)