<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<!-- Created on February 3, 2019 by texi2html 5.0
texi2html was written by:
Lionel Cons <Lionel.Cons@cern.ch> (original author)
Karl Berry <karl@freefriends.org>
Olaf Bachmann <obachman@mathematik.uni-kl.de>
and many others.
Maintained by: Many creative people.
Send bugs and suggestions to <texi2html-bug@nongnu.org>
-->
<head>
<title>zsh: 4 Invocation</title>
<meta name="description" content="zsh: 4 Invocation">
<meta name="keywords" content="zsh: 4 Invocation">
<meta name="resource-type" content="document">
<meta name="distribution" content="global">
<meta name="Generator" content="texi2html 5.0">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<style type="text/css">
<!--
a.summary-letter {text-decoration: none}
blockquote.smallquotation {font-size: smaller}
div.display {margin-left: 3.2em}
div.example {margin-left: 3.2em}
div.lisp {margin-left: 3.2em}
div.smalldisplay {margin-left: 3.2em}
div.smallexample {margin-left: 3.2em}
div.smalllisp {margin-left: 3.2em}
pre.display {font-family: serif}
pre.format {font-family: serif}
pre.menu-comment {font-family: serif}
pre.menu-preformatted {font-family: serif}
pre.smalldisplay {font-family: serif; font-size: smaller}
pre.smallexample {font-size: smaller}
pre.smallformat {font-family: serif; font-size: smaller}
pre.smalllisp {font-size: smaller}
span.nocodebreak {white-space:pre}
span.nolinebreak {white-space:pre}
span.roman {font-family:serif; font-weight:normal}
span.sansserif {font-family:sans-serif; font-weight:normal}
ul.no-bullet {list-style: none}
-->
</style>
</head>
<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
<a name="Invocation"></a>
<table class="header" cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="Roadmap.html#Roadmap" title="Beginning of this chapter or previous chapter"> << </a>]</td>
<td valign="middle" align="left">[<a href="Roadmap.html#Programming" title="Previous section in reading order"> < </a>]</td>
<td valign="middle" align="left">[<a href="index.html#Top" title="Up section"> Up </a>]</td>
<td valign="middle" align="left">[<a href="#Invocation-2" title="Next section in reading order"> > </a>]</td>
<td valign="middle" align="left">[<a href="Files.html#Files" title="Next chapter"> >> </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="index.html#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="zsh_toc.html#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="Concept-Index.html#Concept-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="zsh_abt.html#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="Invocation-1"></a>
<h1 class="chapter">4 Invocation</h1>
<a name="index-invocation"></a>
<hr>
<a name="Invocation-2"></a>
<table class="header" cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#Invocation" title="Beginning of this chapter or previous chapter"> << </a>]</td>
<td valign="middle" align="left">[<a href="#Invocation" title="Previous section in reading order"> < </a>]</td>
<td valign="middle" align="left">[<a href="#Invocation" title="Up section"> Up </a>]</td>
<td valign="middle" align="left">[<a href="#Compatibility" title="Next section in reading order"> > </a>]</td>
<td valign="middle" align="left">[<a href="Files.html#Files" title="Next chapter"> >> </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="index.html#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="zsh_toc.html#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="Concept-Index.html#Concept-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="zsh_abt.html#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<h2 class="section">4.1 Invocation</h2>
<a name="index-shell-options"></a>
<a name="index-options_002c-shell"></a>
<a name="index-shell-flags"></a>
<a name="index-flags_002c-shell"></a>
<p>The following flags are interpreted by the shell when invoked to determine
where the shell will read commands from:
</p>
<dl compact="compact">
<dt><tt>-c</tt></dt>
<dd><p>Take the first argument as a command to execute, rather than reading commands
from a script or standard input. If any further arguments are given, the
first one is assigned to <tt>$0</tt>, rather than being used as a positional
parameter.
</p>
</dd>
<dt><tt>-i</tt></dt>
<dd><p>Force shell to be interactive. It is still possible to specify a
script to execute.
</p>
</dd>
<dt><tt>-s</tt></dt>
<dd><p>Force shell to read commands from the standard input.
If the <tt>-s</tt> flag is not present and an argument is given,
the first argument is taken to be the pathname of a script to
execute.
</p>
</dd>
</dl>
<p>If there are any remaining arguments after option processing, and neither
of the options <tt>-c</tt> or <tt>-s</tt> was supplied, the first argument is taken
as the file name of a script containing shell commands to be executed. If
the option <tt>PATH_SCRIPT</tt> is set, and the file name does not contain a
directory path (i.e. there is no ‘<tt>/</tt>’ in the name), first the current
directory and then the command path given by the variable <tt>PATH</tt> are
searched for the script. If the option is not set or the file name
contains a ‘<tt>/</tt>’ it is used directly.
</p>
<p>After the first one or two arguments have been appropriated as described above,
the remaining arguments are assigned to the positional parameters.
</p>
<p>For further options, which are common to invocation and the <tt>set</tt>
builtin, see
<a href="Options.html#Options">Options</a>.
</p>
<p>The long option ‘<tt>-</tt><tt>-emulate</tt>’ followed (in a separate word) by an
emulation mode may be passed to the shell.
The emulation modes are those described for the <tt>emulate</tt> builtin,
see
<a href="Shell-Builtin-Commands.html#Shell-Builtin-Commands">Shell Builtin Commands</a>.
The ‘<tt>-</tt><tt>-emulate</tt>’ option must precede any other options (which might
otherwise be overridden), but following options are honoured, so
may be used to modify the requested emulation mode. Note that certain
extra steps are taken to ensure a smooth emulation when this option
is used compared with the <tt>emulate</tt> command within the shell: for
example, variables that conflict with POSIX usage such as <tt>path</tt> are
not defined within the shell.
</p>
<p>Options may be specified by name using the <tt>-o</tt> option. <tt>-o</tt> acts like
a single-letter option, but takes a following string as the option name.
For example,
</p>
<div class="example">
<pre class="example">zsh -x -o shwordsplit scr
</pre></div>
<p>runs the script <tt>scr</tt>, setting the <tt>XTRACE</tt> option by the corresponding
letter ‘<tt>-x</tt>’ and the <tt>SH_WORD_SPLIT</tt> option by name.
Options may be turned <em>off</em> by name by using <tt>+o</tt> instead of <tt>-o</tt>.
<tt>-o</tt> can be stacked up with preceding single-letter options, so for example
‘<tt>-xo shwordsplit</tt>’ or ‘<tt>-xoshwordsplit</tt>’ is equivalent to
‘<tt>-x -o shwordsplit</tt>’.
</p>
<a name="index-long-option"></a>
<p>Options may also be specified by name in GNU long option style,
‘<tt>-</tt><tt>-</tt><var>option-name</var>’. When this is done, ‘<tt>-</tt>’ characters in the
option name are permitted: they are translated into ‘<tt>_</tt>’, and thus ignored.
So, for example, ‘<tt>zsh -</tt><tt>-sh-word-split</tt>’ invokes zsh with the
<tt>SH_WORD_SPLIT</tt> option turned on. Like other option syntaxes, options can
be turned off by replacing the initial ‘<tt>-</tt>’ with a ‘<tt>+</tt>’; thus
‘<tt>+-sh-word-split</tt>’ is equivalent to ‘<tt>-</tt><tt>-no-sh-word-split</tt>’.
Unlike other option syntaxes, GNU-style long options cannot be stacked with
any other options, so for example ‘<tt>-x-shwordsplit</tt>’ is an error,
rather than being treated like ‘<tt>-x -</tt><tt>-shwordsplit</tt>’.
</p>
<a name="index-_002d_002dversion"></a>
<a name="index-_002d_002dhelp"></a>
<p>The special GNU-style option ‘<tt>-</tt><tt>-version</tt>’ is handled; it sends to
standard output the shell’s version information, then exits successfully.
‘<tt>-</tt><tt>-help</tt>’ is also handled; it sends to standard output a list of
options that can be used when invoking the shell, then exits successfully.
</p>
<p>Option processing may be finished, allowing following arguments that start with
‘<tt>-</tt>’ or ‘<tt>+</tt>’ to be treated as normal arguments, in two ways.
Firstly, a lone ‘<tt>-</tt>’ (or ‘<tt>+</tt>’) as an argument by itself ends
option processing. Secondly, a special option ‘<tt>-</tt><tt>-</tt>’ (or
‘<tt>+-</tt>’), which may be specified on its own (which is the standard
POSIX usage) or may be stacked with preceding options (so ‘<tt>-x-</tt>’ is
equivalent to ‘<tt>-x -</tt><tt>-</tt>’). Options are not permitted to be stacked
after ‘<tt>-</tt><tt>-</tt>’ (so ‘<tt>-x-f</tt>’ is an error), but note the GNU-style
option form discussed above, where ‘<tt>-</tt><tt>-shwordsplit</tt>’ is permitted
and does not end option processing.
</p>
<p>Except when the <cite>sh</cite>/<cite>ksh</cite> emulation single-letter options are in effect,
the option ‘<tt>-b</tt>’ (or ‘<tt>+b</tt>’) ends option processing.
‘<tt>-b</tt>’ is like ‘<tt>-</tt><tt>-</tt>’, except that further single-letter options
can be stacked after the ‘<tt>-b</tt>’ and will take effect as normal.
</p>
<table class="menu" border="0" cellspacing="0">
<tr><td align="left" valign="top"><a href="#Compatibility">4.2 Compatibility</a></td><td> </td><td align="left" valign="top">
</td></tr>
<tr><td align="left" valign="top"><a href="#Restricted-Shell">4.3 Restricted Shell</a></td><td> </td><td align="left" valign="top">
</td></tr>
</table>
<hr>
<a name="Compatibility"></a>
<table class="header" cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#Invocation" title="Beginning of this chapter or previous chapter"> << </a>]</td>
<td valign="middle" align="left">[<a href="#Invocation-2" title="Previous section in reading order"> < </a>]</td>
<td valign="middle" align="left">[<a href="#Invocation" title="Up section"> Up </a>]</td>
<td valign="middle" align="left">[<a href="#Restricted-Shell" title="Next section in reading order"> > </a>]</td>
<td valign="middle" align="left">[<a href="Files.html#Files" title="Next chapter"> >> </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="index.html#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="zsh_toc.html#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="Concept-Index.html#Concept-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="zsh_abt.html#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="Compatibility-1"></a>
<h2 class="section">4.2 Compatibility</h2>
<a name="index-compatibility"></a>
<a name="index-sh-compatibility"></a>
<a name="index-ksh-compatibility"></a>
<p>Zsh tries to emulate <cite>sh</cite> or <cite>ksh</cite> when it is invoked as
<tt>sh</tt> or <tt>ksh</tt> respectively; more precisely, it looks at the first
letter of the name by which it was invoked, excluding any initial ‘<tt>r</tt>’
(assumed to stand for ‘restricted’), and if that is ‘<tt>b</tt>’, ‘<tt>s</tt>’ or ‘<tt>k</tt>’ it
will emulate <cite>sh</cite> or <cite>ksh</cite>. Furthermore, if invoked as <tt>su</tt> (which
happens on certain systems when the shell is executed by the <tt>su</tt>
command), the shell will try to find an alternative name from the <tt>SHELL</tt>
environment variable and perform emulation based on that.
</p>
<p>In <cite>sh</cite> and <cite>ksh</cite> compatibility modes the following
parameters are not special and not initialized by the shell:
<tt>ARGC</tt>,
<tt>argv</tt>,
<tt>cdpath</tt>,
<tt>fignore</tt>,
<tt>fpath</tt>,
<tt>HISTCHARS</tt>,
<tt>mailpath</tt>,
<tt>MANPATH</tt>,
<tt>manpath</tt>,
<tt>path</tt>,
<tt>prompt</tt>,
<tt>PROMPT</tt>,
<tt>PROMPT2</tt>,
<tt>PROMPT3</tt>,
<tt>PROMPT4</tt>,
<tt>psvar</tt>,
<tt>status</tt>,
<tt>watch</tt>.
</p>
<a name="index-ENV_002c-use-of"></a>
<p>The usual zsh startup/shutdown scripts are not executed. Login shells
source <tt>/etc/profile</tt> followed by <tt>$HOME/.profile</tt>. If the
<tt>ENV</tt> environment variable is set on invocation, <tt>$ENV</tt> is sourced
after the profile scripts. The value of <tt>ENV</tt> is subjected to
parameter expansion, command substitution, and arithmetic expansion
before being interpreted as a pathname. Note that the <tt>PRIVILEGED</tt>
option also affects the execution of startup files.
</p>
<p>The following options are set if the shell is invoked as <tt>sh</tt> or
<tt>ksh</tt>:
<tt>NO_BAD_PATTERN</tt>,
<tt>NO_BANG_HIST</tt>,
<tt>NO_BG_NICE</tt>,
<tt>NO_EQUALS</tt>,
<tt>NO_FUNCTION_ARGZERO</tt>,
<tt>GLOB_SUBST</tt>,
<tt>NO_GLOBAL_EXPORT</tt>,
<tt>NO_HUP</tt>,
<tt>INTERACTIVE_COMMENTS</tt>,
<tt>KSH_ARRAYS</tt>,
<tt>NO_MULTIOS</tt>,
<tt>NO_NOMATCH</tt>,
<tt>NO_NOTIFY</tt>,
<tt>POSIX_BUILTINS</tt>,
<tt>NO_PROMPT_PERCENT</tt>,
<tt>RM_STAR_SILENT</tt>,
<tt>SH_FILE_EXPANSION</tt>,
<tt>SH_GLOB</tt>,
<tt>SH_OPTION_LETTERS</tt>,
<tt>SH_WORD_SPLIT</tt>.
Additionally the <tt>BSD_ECHO</tt> and <tt>IGNORE_BRACES</tt>
options are set if zsh is invoked as <tt>sh</tt>.
Also, the
<tt>KSH_OPTION_PRINT</tt>,
<tt>LOCAL_OPTIONS</tt>,
<tt>PROMPT_BANG</tt>,
<tt>PROMPT_SUBST</tt>
and
<tt>SINGLE_LINE_ZLE</tt>
options are set if zsh is invoked as <tt>ksh</tt>.
</p><hr>
<a name="Restricted-Shell"></a>
<table class="header" cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#Invocation" title="Beginning of this chapter or previous chapter"> << </a>]</td>
<td valign="middle" align="left">[<a href="#Compatibility" title="Previous section in reading order"> < </a>]</td>
<td valign="middle" align="left">[<a href="#Invocation" title="Up section"> Up </a>]</td>
<td valign="middle" align="left">[<a href="Files.html#Files" title="Next section in reading order"> > </a>]</td>
<td valign="middle" align="left">[<a href="Files.html#Files" title="Next chapter"> >> </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="index.html#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="zsh_toc.html#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="Concept-Index.html#Concept-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="zsh_abt.html#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<a name="Restricted-Shell-1"></a>
<h2 class="section">4.3 Restricted Shell</h2>
<a name="index-restricted-shell"></a>
<a name="index-RESTRICTED"></a>
<p>When the basename of the command used to invoke zsh starts with the letter
‘<tt>r</tt>’ or the ‘<tt>-r</tt>’ command line option is supplied at invocation, the
shell becomes restricted. Emulation mode is determined after stripping the
letter ‘<tt>r</tt>’ from the invocation name. The following are disabled in
restricted mode:
</p>
<ul>
<li>
changing directories with the <tt>cd</tt> builtin
</li><li>
changing or unsetting the <tt>EGID</tt>, <tt>EUID</tt>, <tt>GID</tt>,
<tt>HISTFILE</tt>, <tt>HISTSIZE</tt>, <tt>IFS</tt>, <tt>LD_AOUT_LIBRARY_PATH</tt>,
<tt>LD_AOUT_PRELOAD</tt>, <tt>LD_LIBRARY_PATH</tt>, <tt>LD_PRELOAD</tt>,
<tt>MODULE_PATH</tt>, <tt>module_path</tt>, <tt>PATH</tt>, <tt>path</tt>, <tt>SHELL</tt>,
<tt>UID</tt> and <tt>USERNAME</tt> parameters
</li><li>
specifying command names containing <tt>/</tt>
</li><li>
specifying command pathnames using <tt>hash</tt>
</li><li>
redirecting output to files
</li><li>
using the <tt>exec</tt> builtin command to replace the shell with another
command
</li><li>
using <tt>jobs -Z</tt> to overwrite the shell process’ argument and
environment space
</li><li>
using the <tt>ARGV0</tt> parameter to override <tt>argv[0]</tt> for external
commands
</li><li>
turning off restricted mode with <tt>set +r</tt> or <tt>unsetopt
RESTRICTED</tt>
</li></ul>
<p>These restrictions are enforced after processing the startup files. The
startup files should set up <tt>PATH</tt> to point to a directory of commands
which can be safely invoked in the restricted environment. They may also
add further restrictions by disabling selected builtins.
</p>
<p>Restricted mode can also be activated any time by setting the
<tt>RESTRICTED</tt> option. This immediately enables all the restrictions
described above even if the shell still has not processed all startup
files.
</p><hr>
<table class="header" cellpadding="1" cellspacing="1" border="0">
<tr><td valign="middle" align="left">[<a href="#Invocation" title="Beginning of this chapter or previous chapter"> << </a>]</td>
<td valign="middle" align="left">[<a href="Files.html#Files" title="Next chapter"> >> </a>]</td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left"> </td>
<td valign="middle" align="left">[<a href="index.html#Top" title="Cover (top) of document">Top</a>]</td>
<td valign="middle" align="left">[<a href="zsh_toc.html#SEC_Contents" title="Table of contents">Contents</a>]</td>
<td valign="middle" align="left">[<a href="Concept-Index.html#Concept-Index" title="Index">Index</a>]</td>
<td valign="middle" align="left">[<a href="zsh_abt.html#SEC_About" title="About (help)"> ? </a>]</td>
</tr></table>
<p>
<font size="-1">
This document was generated on <i>February 3, 2019</i> using <a href="http://www.nongnu.org/texi2html/"><i>texi2html 5.0</i></a>.
</font>
<br>
<font size="-1">Zsh version 5.7.1, released on February 3, 2019.</font>
</p>
</body>
</html>
