Go to main content

man pages section 1: User Commands

Exit Print View

Updated: Wednesday, February 9, 2022
 
 

zsh (1)

Name

zsh - the Z shell

Synopsis

Please see following description for synopsis

Description

ZSH(1)                      General Commands Manual                     ZSH(1)



NAME
       zsh - the Z shell

OVERVIEW
       Because  zsh contains many features, the zsh manual has been split into
       a number of sections:

       zsh          Zsh overview (this section)
       zshroadmap   Informal introduction to the manual
       zshmisc      Anything not fitting into the other sections
       zshexpn      Zsh command and parameter expansion
       zshparam     Zsh parameters
       zshoptions   Zsh options
       zshbuiltins  Zsh built-in functions
       zshzle       Zsh command line editing
       zshcompwid   Zsh completion widgets
       zshcompsys   Zsh completion system
       zshcompctl   Zsh completion control
       zshmodules   Zsh loadable modules
       zshcalsys    Zsh built-in calendar functions
       zshtcpsys    Zsh built-in TCP functions
       zshzftpsys   Zsh built-in FTP client
       zshcontrib   Additional zsh functions and utilities
       zshall       Meta-man page containing all of the above

DESCRIPTION
       Zsh is a UNIX command interpreter  (shell)  usable  as  an  interactive
       login  shell  and as a shell script command processor.  Of the standard
       shells, zsh most closely resembles ksh but includes many  enhancements.
       It  does  not  provide  compatibility with POSIX or other shells in its
       default operating mode:  see the section Compatibility below.

       Zsh has command line editing, builtin spelling correction, programmable
       command completion, shell functions (with autoloading), a history mech-
       anism, and a host of other features.

AUTHOR
       Zsh was originally written by Paul Falstad <pf@zsh.org>.   Zsh  is  now
       maintained  by  the  members of the zsh-workers mailing list <zsh-work-
       ers@zsh.org>.   The  development  is  currently  coordinated  by  Peter
       Stephenson <pws@zsh.org>.  The coordinator can be contacted at <coordi-
       nator@zsh.org>, but matters relating to the code should generally go to
       the mailing list.

AVAILABILITY
       Zsh is available from the following HTTP and anonymous FTP site.

       ftp://ftp.zsh.org/pub/
       https://www.zsh.org/pub/
       )

       The  up-to-date source code is available via Git from Sourceforge.  See
       https://sourceforge.net/projects/zsh/  for  details.   A   summary   of
       instructions  for  the  archive  can  be  found  at  http://zsh.source-
       forge.net/.

MAILING LISTS
       Zsh has 3 mailing lists:

       <zsh-announce@zsh.org>
              Announcements about releases, major changes in the shell and the
              monthly posting of the Zsh FAQ.  (moderated)

       <zsh-users@zsh.org>
              User discussions.

       <zsh-workers@zsh.org>
              Hacking, development, bug reports and patches.

       To subscribe or unsubscribe, send mail to the associated administrative
       address for the mailing list.

       <zsh-announce-subscribe@zsh.org>
       <zsh-users-subscribe@zsh.org>
       <zsh-workers-subscribe@zsh.org>
       <zsh-announce-unsubscribe@zsh.org>
       <zsh-users-unsubscribe@zsh.org>
       <zsh-workers-unsubscribe@zsh.org>

       YOU ONLY NEED TO JOIN ONE OF THE MAILING LISTS AS THEY ARE NESTED.  All
       submissions  to  zsh-announce are automatically forwarded to zsh-users.
       All submissions to zsh-users are automatically forwarded  to  zsh-work-
       ers.

       If  you  have  problems subscribing/unsubscribing to any of the mailing
       lists, send mail to <listmaster@zsh.org>.  The mailing lists are  main-
       tained by Karsten Thygesen <karthy@kom.auc.dk>.

       The  mailing  lists  are archived; the archives can be accessed via the
       administrative addresses listed above.  There is also a  hypertext  ar-
       chive,   maintained   by   Geoff   Wing   <gcw@zsh.org>,  available  at
       https://www.zsh.org/mla/.

THE ZSH FAQ
       Zsh has a list of Frequently Asked Questions (FAQ), maintained by Peter
       Stephenson  <pws@zsh.org>.   It  is  regularly  posted to the newsgroup
       comp.unix.shell and the zsh-announce mailing list.  The latest  version
       can    be    found   at   any   of   the   Zsh   FTP   sites,   or   at
       http://www.zsh.org/FAQ/.  The contact address for  FAQ-related  matters
       is <faqmaster@zsh.org>.

THE ZSH WEB PAGE
       Zsh  has  a web page which is located at https://www.zsh.org/.  This is
       maintained by Karsten Thygesen <karthy@zsh.org>,  of  SunSITE  Denmark.
       The contact address for web-related matters is <webmaster@zsh.org>.

THE ZSH USERGUIDE
       A  userguide is currently in preparation.  It is intended to complement
       the manual, with explanations and hints on issues where the manual  can
       be cabbalistic, hierographic, or downright mystifying (for example, the
       word `hierographic' does not exist).  It can be viewed in  its  current
       state  at  http://zsh.sourceforge.net/Guide/.   At the time of writing,
       chapters dealing with startup files and their contents and the new com-
       pletion system were essentially complete.

INVOCATION
       The following flags are interpreted by the shell when invoked to deter-
       mine where the shell will read commands from:

       -c     Take the first argument as a command  to  execute,  rather  than
              reading  commands  from a script or standard input.  If any fur-
              ther arguments are given, the  first  one  is  assigned  to  $0,
              rather than being used as a positional parameter.

       -i     Force  shell to be interactive.  It is still possible to specify
              a script to execute.

       -s     Force shell to read commands from the standard input.  If the -s
              flag is not present and an argument is given, the first argument
              is taken to be the pathname of a script to execute.

       If there are any remaining arguments after option processing, and  nei-
       ther  of the options -c or -s was supplied, the first argument is taken
       as the file name of a script containing shell commands to be  executed.
       If  the option PATH_SCRIPT is set, and the file name does not contain a
       directory path (i.e. there is no `/' in the name),  first  the  current
       directory  and  then  the  command  path given by the variable PATH are
       searched for the script.  If the option is not set  or  the  file  name
       contains a `/' it is used directly.

       After  the  first  one  or  two  arguments  have  been  appropriated as
       described above, the remaining arguments are assigned to the positional
       parameters.

       For  further  options,  which  are  common  to  invocation  and the set
       builtin, see zshoptions(1).

       The long option `--emulate' followed (in a separate word) by an  emula-
       tion  mode  may  be passed to the shell.  The emulation modes are those
       described for the emulate builtin, see zshbuiltins(1).  The `--emulate'
       option  must  precede any other options (which might otherwise be over-
       ridden), but following options are honoured, so may be used  to  modify
       the  requested emulation mode.  Note that certain extra steps are taken
       to ensure a smooth emulation when this option is used compared with the
       emulate  command within the shell: for example, variables that conflict
       with POSIX usage such as path are not defined within the shell.

       Options may be specified by name using the -o option.  -o acts  like  a
       single-letter  option, but takes a following string as the option name.
       For example,

              zsh -x -o shwordsplit scr

       runs the script scr, setting the XTRACE  option  by  the  corresponding
       letter  `-x'  and  the  SH_WORD_SPLIT  option  by name.  Options may be
       turned off by name by using +o instead of -o.  -o  can  be  stacked  up
       with  preceding single-letter options, so for example `-xo shwordsplit'
       or `-xoshwordsplit' is equivalent to `-x -o shwordsplit'.

       Options may also be  specified  by  name  in  GNU  long  option  style,
       `--option-name'.   When this is done, `-' characters in the option name
       are permitted: they are translated into `_', and thus ignored.  So, for
       example,  `zsh  --sh-word-split'  invokes  zsh  with  the SH_WORD_SPLIT
       option turned on.  Like other option syntaxes, options  can  be  turned
       off  by replacing the initial `-' with a `+'; thus `+-sh-word-split' is
       equivalent to  `--no-sh-word-split'.   Unlike  other  option  syntaxes,
       GNU-style long options cannot be stacked with any other options, so for
       example `-x-shwordsplit' is an error, rather than  being  treated  like
       `-x --shwordsplit'.

       The  special GNU-style option `--version' is handled; it sends to stan-
       dard output the shell's version information, then  exits  successfully.
       `--help' is also handled; it sends to standard output a list of options
       that can be used when invoking the shell, then exits successfully.

       Option processing may be finished, allowing  following  arguments  that
       start  with  `-' or `+' to be treated as normal arguments, in two ways.
       Firstly, a lone `-' (or `+') as an argument by itself ends option  pro-
       cessing.  Secondly, a special option `--' (or `+-'), which may be spec-
       ified on its own (which is the standard POSIX usage) or may be  stacked
       with  preceding  options  (so `-x-' is equivalent to `-x --').  Options
       are not permitted to be stacked after `--' (so `-x-f' is an error), but
       note  the  GNU-style option form discussed above, where `--shwordsplit'
       is permitted and does not end option processing.

       Except when the sh/ksh emulation single-letter options are  in  effect,
       the  option  `-b' (or `+b') ends option processing.  `-b' is like `--',
       except that further single-letter options can be stacked after the `-b'
       and will take effect as normal.

COMPATIBILITY
       Zsh  tries to emulate sh or ksh when it is invoked as sh or ksh respec-
       tively; more precisely, it looks at the first letter  of  the  name  by
       which  it  was invoked, excluding any initial `r' (assumed to stand for
       `restricted'), and if that is `b', `s' or `k' it  will  emulate  sh  or
       ksh.   Furthermore,  if invoked as su (which happens on certain systems
       when the shell is executed by the su command), the shell  will  try  to
       find  an  alternative name from the SHELL environment variable and per-
       form emulation based on that.

       In sh and ksh compatibility modes the following parameters are not spe-
       cial  and  not  initialized  by the shell: ARGC, argv, cdpath, fignore,
       fpath, HISTCHARS, mailpath, MANPATH,  manpath,  path,  prompt,  PROMPT,
       PROMPT2, PROMPT3, PROMPT4, psvar, status, watch.

       The  usual zsh startup/shutdown scripts are not executed.  Login shells
       source /etc/profile followed by $HOME/.profile.  If the ENV environment
       variable  is  set  on  invocation,  $ENV  is  sourced after the profile
       scripts.  The value of ENV is subjected to parameter expansion, command
       substitution,  and  arithmetic  expansion before being interpreted as a
       pathname.  Note that the PRIVILEGED option also affects  the  execution
       of startup files.

       The  following  options  are  set if the shell is invoked as sh or ksh:
       NO_BAD_PATTERN,   NO_BANG_HIST,   NO_BG_NICE,    NO_EQUALS,    NO_FUNC-
       TION_ARGZERO,  GLOB_SUBST,  NO_GLOBAL_EXPORT,  NO_HUP, INTERACTIVE_COM-
       MENTS, KSH_ARRAYS, NO_MULTIOS, NO_NOMATCH,  NO_NOTIFY,  POSIX_BUILTINS,
       NO_PROMPT_PERCENT,    RM_STAR_SILENT,    SH_FILE_EXPANSION,    SH_GLOB,
       SH_OPTION_LETTERS,  SH_WORD_SPLIT.   Additionally  the   BSD_ECHO   and
       IGNORE_BRACES  options  are  set  if  zsh  is invoked as sh.  Also, the
       KSH_OPTION_PRINT, LOCAL_OPTIONS,  PROMPT_BANG,  PROMPT_SUBST  and  SIN-
       GLE_LINE_ZLE options are set if zsh is invoked as ksh.

RESTRICTED SHELL
       When  the  basename  of  the command used to invoke zsh starts with the
       letter `r' or the `-r' command line option is supplied  at  invocation,
       the  shell  becomes  restricted.   Emulation  mode  is determined after
       stripping the letter `r' from the invocation name.  The  following  are
       disabled in restricted mode:

       o      changing directories with the cd builtin

       o      changing  or  unsetting the EGID, EUID, GID, HISTFILE, HISTSIZE,
              IFS,  LD_AOUT_LIBRARY_PATH,  LD_AOUT_PRELOAD,   LD_LIBRARY_PATH,
              LD_PRELOAD, MODULE_PATH, module_path, PATH, path, SHELL, UID and
              USERNAME parameters

       o      specifying command names containing /

       o      specifying command pathnames using hash

       o      redirecting output to files

       o      using the exec builtin command to replace the shell with another
              command

       o      using jobs -Z to overwrite the shell process' argument and envi-
              ronment space

       o      using the ARGV0 parameter to override argv[0] for external  com-
              mands

       o      turning off restricted mode with set +r or unsetopt RESTRICTED

       These  restrictions  are  enforced  after processing the startup files.
       The startup files should set up PATH to point to a  directory  of  com-
       mands  which can be safely invoked in the restricted environment.  They
       may also add further restrictions by disabling selected builtins.

       Restricted  mode  can  also  be  activated  any  time  by  setting  the
       RESTRICTED  option.   This  immediately  enables  all  the restrictions
       described above even if the shell still has not processed  all  startup
       files.

       A  shell  Restricted Mode is an outdated way to restrict what users may
       do:  modern systems have better, safer and more reliable ways  to  con-
       fine user actions, such as chroot jails, containers and zones.

       A  restricted shell is very difficult to implement safely.  The feature
       may be removed in a future version of zsh.

       It is important to realise that the  restrictions  only  apply  to  the
       shell,  not  to  the commands it runs (except for some shell builtins).
       While a restricted shell can only run the restricted list  of  commands
       accessible  via  the  predefined  `PATH'  variable, it does not prevent
       those commands from running any other command.

       As an example, if `env' is among the list of allowed commands, then  it
       allows the user to run any command as `env' is not a shell builtin com-
       mand and can run arbitrary executables.

       So when implementing a restricted shell framework it is important to be
       fully  aware  of  what actions each of the allowed commands or features
       (which may be regarded as modules) can perform.

       Many commands can have their behaviour affected  by  environment  vari-
       ables.  Except for the few listed above, zsh does not restrict the set-
       ting of environment variables.

       If a `perl', `python', `bash', or  other  general  purpose  interpreted
       script it treated as a restricted command, the user can work around the
       restriction by  setting  specially  crafted  `PERL5LIB',  `PYTHONPATH',
       `BASHENV' (etc.) environment variables. On GNU systems, any command can
       be made to run arbitrary code when performing character set  conversion
       (including  zsh itself) by setting a `GCONV_PATH' environment variable.
       Those are only a few examples.

       Bear in mind that, contrary to some other shells, `readonly' is  not  a
       security  feature  in  zsh as it can be undone and so cannot be used to
       mitigate the above.

       A restricted shell only works if the allowed commands are few and care-
       fully  written  so  as not to grant more access to users than intended.
       It is also important to restrict what zsh module the user may  load  as
       some  of  them,  such  as  `zsh/system', `zsh/mapfile' and `zsh/files',
       allow bypassing most of the restrictions.

STARTUP/SHUTDOWN FILES
       Commands are first read from /etc/zshenv; this  cannot  be  overridden.
       Subsequent behaviour is modified by the RCS and GLOBAL_RCS options; the
       former affects all startup files, while the second only affects  global
       startup  files  (those  shown here with an path starting with a /).  If
       one of the options is  unset  at  any  point,  any  subsequent  startup
       file(s)  of the corresponding type will not be read.  It is also possi-
       ble for a file in  $ZDOTDIR  to  re-enable  GLOBAL_RCS.  Both  RCS  and
       GLOBAL_RCS are set by default.

       Commands  are then read from $ZDOTDIR/.zshenv.  If the shell is a login
       shell, commands are read from /etc/zprofile  and  then  $ZDOTDIR/.zpro-
       file.   Then,  if  the  shell  is  interactive,  commands are read from
       /etc/zshrc and then $ZDOTDIR/.zshrc.  Finally, if the shell is a  login
       shell, /etc/zlogin and $ZDOTDIR/.zlogin are read.

       When  a  login  shell  exits,  the  files  $ZDOTDIR/.zlogout  and  then
       /etc/zlogout are read.  This happens with either an explicit  exit  via
       the exit or logout commands, or an implicit exit by reading end-of-file
       from the terminal.  However, if the shell terminates  due  to  exec'ing
       another  process,  the  logout  files  are  not  read.   These are also
       affected by the RCS and GLOBAL_RCS options.  Note  also  that  the  RCS
       option  affects  the saving of history files, i.e. if RCS is unset when
       the shell exits, no history file will be saved.

       If ZDOTDIR is unset, HOME is used instead.  Files listed above as being
       in /etc may be in another directory, depending on the installation.

       As /etc/zshenv is run for all instances of zsh, it is important that it
       be kept as small as possible.  In particular, it is a good idea to  put
       code  that does not need to be run for every single shell behind a test
       of the form `if [[ -o rcs ]]; then ...' so that it will not be executed
       when zsh is invoked with the `-f' option.

       Any  of  these files may be pre-compiled with the zcompile builtin com-
       mand (see zshbuiltins(1)).  If a compiled file exists  (named  for  the
       original  file plus the .zwc extension) and it is newer than the origi-
       nal file, the compiled file will be used instead.

FILES
       $ZDOTDIR/.zshenv
       $ZDOTDIR/.zprofile
       $ZDOTDIR/.zshrc
       $ZDOTDIR/.zlogin
       $ZDOTDIR/.zlogout
       ${TMPPREFIX}*   (default is /tmp/zsh*)
       /etc/zshenv
       /etc/zprofile
       /etc/zshrc
       /etc/zlogin
       /etc/zlogout    (installation-specific - /etc is the default)

SEE ALSO
       sh(1),  csh(1),  tcsh(1),  rc(1),  bash(1),  ksh(1),  zshall(1),   zsh-
       builtins(1), zshcalsys(1), zshcompwid(1), zshcompsys(1), zshcompctl(1),
       zshcontrib(1), zshexpn(1),  zshmisc(1),  zshmodules(1),  zshoptions(1),
       zshparam(1), zshroadmap(1), zshtcpsys(1), zshzftpsys(1), zshzle(1)

       IEEE  Standard  for  information Technology - Portable Operating System
       Interface (POSIX) - Part 2: Shell and Utilities, IEEE Inc,  1993,  ISBN
       1-55937-255-9.



zsh 5.8                        February 14, 2020                        ZSH(1)