ZSH(1)                      General Commands Manual                     ZSH(1)

       zsh - the Z shell

       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

       Zsh is a UNIX command interpreter (shell) usable as an interactive  lo-
       gin  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 de-
       fault 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.

       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.

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


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

       Zsh has 3 mailing lists:

              Announcements about releases, major changes in the shell and the
              monthly posting of the Zsh FAQ.  (moderated)

              User discussions.

              Hacking, development, bug reports and patches.

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


       submissions to zsh-announce are automatically forwarded  to  zsh-users.
       All  submissions  to zsh-users are automatically forwarded to zsh-work-

       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

       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>.

       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>.

       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.

       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  de-
       scribed  above,  the remaining arguments are assigned to the positional

       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, `--op-
       tion-name'.  When this is done, `-' characters in the option  name  are
       permitted: they are translated into `_', and thus ignored.  So, for ex-
       ample, `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 equiva-
       lent  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

       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.

       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:
       TION_LETTERS,   SH_WORD_SPLIT.    Additionally  the  BSD_ECHO  and  IG-
       NORE_BRACES options are set if zsh is invoked as sh.  Also, the KSH_OP-
       GLE_LINE_ZLE options are set if zsh is invoked as ksh.

       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,
              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

       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-

       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 RE-
       STRICTED option.  This immediately enables  all  the  restrictions  de-
       scribed  above  even  if  the shell still has not processed all startup

       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',  al-
       low bypassing most of the restrictions.

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

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

       When  a  login  shell  exits,  the  files  $ZDOTDIR/.zlogout  and  then
       /etc/zsh/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/zsh/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.

       ${TMPPREFIX}*   (default is /tmp/zsh*)
       /etc/zsh/zlogout    (installation-specific - /etc is the default)

       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

zsh 5.8                        February 14, 2020                        ZSH(1)

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