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    <title>execline: a small scripting language</title>
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    <meta name="Keywords" content="execline script scripting language shell embedded chain loading bernstein chaining unix" />
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<p>
<a href="//skarnet.org/software/">Software</a><br />
<a href="//skarnet.org/">skarnet.org</a>
</p>

<h1> execline </h1>

<h2> What is it? </h2>

<p>
 execline is a (non-interactive) scripting language, like <tt>sh</tt> -
but its syntax is quite different from a traditional shell syntax.
The <tt>execlineb</tt> program is meant to be used as an interpreter for a
text file; the other commands are essentially useful inside an
<tt>execlineb</tt> script.
</p>

<p>
 execline is as powerful as a shell: it features
<a href="loopwhilex.html">conditional loops</a>,
<a href="elgetopt.html">getopt-style option handling</a>,
<a href="elglob.html">filename globbing</a>, and more.
 Meanwhile, its syntax is far more logic and predictable than the
shell's syntax, and has no security issues.
</p>

<ul>
<li> <a href="grammar.html">The execline design and grammar</a></li>
<li> <a href="dieshdiedie.html">Why not just use <tt>/bin/sh</tt>?</a></li>
</ul>

<hr />

<h2> Installation </h2>

<h3> Requirements </h3>

<ul>
 <li> A POSIX-compliant system with a standard C development environment </li>
 <li> GNU make, version 3.81 or later. </li>
 <li> <a href="//skarnet.org/software/skalibs/">skalibs</a> version
2.10.0.2 or later. It's a build-time requirement. It's also a run-time
requirement if you link against the shared version of the skalibs
library. </li>
</ul>

<p>
 The following optional dependencies are also supported:
</p>

<ul>
 <li> If you're using <a href="https://www.musl-libc.org/">musl</a> and
want nsswitch-like functionality:
<a href="//skarnet.org/software/nsss/">nsss</a> version
0.1.0.0 or later (build-time and boot-time) </li>
</ul>

<h3> Licensing </h3>

<p>
 execline is free software. It is available under the
<a href="https://opensource.org/licenses/ISC">ISC license</a>.
</p>

<h3> Download </h3>

<ul>
 <li> The current released version of execline is <a href="execline-2.8.0.0.tar.gz">2.8.0.0</a>. </li>
 <li> Alternatively, you can checkout a copy of the
<a href="//git.skarnet.org/cgi-bin/cgit.cgi/execline/">execline
git repository</a>:
<pre> git clone git://git.skarnet.org/execline </pre> </li>
 <li> There's also a
<a href="https://github.com/skarnet/execline">GitHub mirror</a>
of the execline git repository. </li>
</ul>

<h3> Compilation </h3>

<ul>
 <li> See the enclosed INSTALL file for installation details. </li>
</ul>

<h3> Upgrade notes </h3>

<ul>
 <li> <a href="upgrade.html">This page</a> lists the differences to be aware of between
the previous versions of execline and the current one. </li>
</ul>

<hr />

<h2> Special note </h2>

<p>
 Before version 2.0.0.0, execline used the slashpackage convention by default.
 This is not the case anymore; nevertheless, the examples in this documentation
still use <tt>#!/command/execlineb</tt> as their shebang line, and assume that
the execline binaries are available in <tt>/command</tt>. Adapt them according
to your installation: the shebang lines for your system might be something like
<tt>#!/bin/execlineb</tt>, or <tt>#!/usr/bin/execlineb</tt>, or
<tt>#!/usr/local/bin/execlineb</tt>, or something else entirely.
</p>

<hr />

<h2> Reference </h2>
<h3> Commands </h3>

<p>
 All these commands exit 111 if they encounter a temporary error, and
100 if they encounter a permanent error - such as a misuse. They exit
127 if they're trying to execute into a program and cannot find it, and
126 if they fail to execute into a program for another reason.
</p>

<p>
 (Script parser / launcher)
</p>
<ul>
<li><a href="execlineb.html">The <tt>execlineb</tt> program</a></li>
</ul>
<p>
 (Process state control)
</p>
<ul>
<li><a href="execline-cd.html">The <tt>execline-cd</tt> program</a></li>
<li><a href="posix-cd.html">The <tt>posix-cd</tt> program</a></li>
<li><a href="execline-umask.html">The <tt>execline-umask</tt> program</a></li>
<li><a href="posix-umask.html">The <tt>posix-umask</tt> program</a></li>
<li><a href="emptyenv.html">The <tt>emptyenv</tt> program</a></li>
<li><a href="envfile.html">The <tt>envfile</tt> program</a></li>
<li><a href="export.html">The <tt>export</tt> program</a></li>
<li><a href="unexport.html">The <tt>unexport</tt> program</a></li>
<li><a href="fdclose.html">The <tt>fdclose</tt> program</a></li>
<li><a href="fdblock.html">The <tt>fdblock</tt> program</a></li>
<li><a href="fdmove.html">The <tt>fdmove</tt> program</a></li>
<li><a href="fdswap.html">The <tt>fdswap</tt> program</a></li>
<li><a href="fdreserve.html">The <tt>fdreserve</tt> program</a></li>
<li><a href="redirfd.html">The <tt>redirfd</tt> program</a></li>
<li><a href="piperw.html">The <tt>piperw</tt> program</a></li>
<li><a href="heredoc.html">The <tt>heredoc</tt> program</a></li>
<li><a href="wait.html">The <tt>wait</tt> program</a></li>
<li><a href="getcwd.html">The <tt>getcwd</tt> program</a></li>
<li><a href="getpid.html">The <tt>getpid</tt> program</a></li>
<li><a href="exec.html">The <tt>exec</tt> program</a></li>
<li><a href="tryexec.html">The <tt>tryexec</tt> program</a></li>
<li><a href="exit.html">The <tt>exit</tt> program</a></li>
<li><a href="trap.html">The <tt>trap</tt> program</a></li>
<li><a href="withstdinas.html">The <tt>withstdinas</tt> program</a></li>
</ul>
<p>
 (<a href="el_semicolon.html">Basic block management</a>)
</p>
<ul>
<li><a href="foreground.html">The <tt>foreground</tt> program</a></li>
<li><a href="background.html">The <tt>background</tt> program</a></li>
<li><a href="if.html">The <tt>if</tt> program</a></li>
<li><a href="ifelse.html">The <tt>ifelse</tt> program</a></li>
<li><a href="ifte.html">The <tt>ifte</tt> program</a></li>
<li><a href="ifthenelse.html">The <tt>ifthenelse</tt> program</a></li>
<li><a href="backtick.html">The <tt>backtick</tt> program</a></li>
<li><a href="pipeline.html">The <tt>pipeline</tt> program</a></li>
<li><a href="runblock.html">The <tt>runblock</tt> program</a></li>
</ul>
<p>
 (<a href="el_substitute.html">Variable management</a>)
</p>
<ul>
<li><a href="define.html">The <tt>define</tt> program</a></li>
<li><a href="importas.html">The <tt>importas</tt> program</a></li>
<li><a href="elglob.html">The <tt>elglob</tt> program</a></li>
<li><a href="elgetpositionals.html">The <tt>elgetpositionals</tt> program</a></li>
<li><a href="multidefine.html">The <tt>multidefine</tt> program</a></li>
<li><a href="multisubstitute.html">The <tt>multisubstitute</tt> program</a></li>
</ul>
<p>
 (Loops)
</p>
<ul>
<li><a href="forx.html">The <tt>forx</tt> program</a></li>
<li><a href="forstdin.html">The <tt>forstdin</tt> program</a></li>
<li><a href="forbacktickx.html">The <tt>forbacktickx</tt> program</a></li>
<li><a href="loopwhilex.html">The <tt>loopwhilex</tt> program</a></li>
</ul>
<p>
 (Positional parameters and options management)
</p>
<ul>
<li><a href="elgetopt.html">The <tt>elgetopt</tt> program</a></li>
<li><a href="shift.html">The <tt>shift</tt> program</a></li>
<li><a href="dollarat.html">The <tt>dollarat</tt> program</a></li>
</ul>
<p>
 (Miscellaneous)
</p>
<ul>
<li><a href="homeof.html">The <tt>homeof</tt> program</a></li>
</ul>

<h3> Provided scripts: example <tt>.profile</tt> replacement </h3>

<ul>
<li><a href="execline-shell.html">The <tt>execline-shell</tt> script</a></li>
<li><a href="execline-startup.html">The <tt>execline-startup</tt> script</a></li>
</ul>

<h3> Fun stuff </h3>

<ul>
<li>An execline <a href="quine-jriou.txt">quine</a>. This was quinely provided by
<a href="http://jriou.org/">Jo&euml;l Riou</a>. The only
external command used is <tt>echo</tt>. </li>
<li> Another <a href="quine-prj.txt">quine</a>, provided by
<a href="https://code.dogmap.org/">Paul Jarc</a>. It is much shorter, but
uses the external commands <tt>echo</tt> and <tt>env</tt>. Later, Paul rewrote
it <a href="quine-prj-2.txt">using only <tt>echo</tt></a>, then
<a href="quine-prj-3.txt">using only <tt>echo</tt> and the environment</a>. </li>
<li> Another <a href="quine-dam.txt">quine</a>, provided by
<a href="http://www.madore.org/~david/">David Madore</a>. It uses the
external command <tt>printf</tt>. It is longer, but quite stylish. </li>
</ul>

<h2> Related resources </h2>

<ul>
 <li> <tt>execline</tt> is discussed on the
<a href="//skarnet.org/lists.html#skaware">skaware</a> mailing-list. </li>
</ul>

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