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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  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.

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  in-
       structions for the archive can be found at http://zsh.sourceforge.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  de-
       scribed	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,	`--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
       --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_OP-
       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-
       TION_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 RE-
       STRICTED	option.	 This immediately enables  all	the  restrictions  de-
       scribed	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',  al-
       low 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/zl-
       ogout 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)

NAME | OVERVIEW | DESCRIPTION | AUTHOR | AVAILABILITY | MAILING LISTS | THE ZSH FAQ | THE ZSH WEB PAGE | THE ZSH USERGUIDE | INVOCATION | COMPATIBILITY | RESTRICTED SHELL | STARTUP/SHUTDOWN FILES | FILES | SEE ALSO

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