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<html>
<head>
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<title>execline: the backtick command</title>
<meta name="Description" content="execline: the backtick command" />
<meta name="Keywords" content="execline command backtick" />
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<p>
<a href="index.html">execline</a><br />
<a href="http://skarnet.org/software/">Software</a><br />
<a href="http://skarnet.org/">skarnet.org</a>
</p>
<h1> The <tt>backtick</tt> program </h1>
<p>
<tt>backtick</tt> runs a program and uses its output as the argument of
another program.
</p>
<h2> Interface </h2>
<p>
In an <a href="execlineb.html">execlineb</a> script:
</p>
<pre>
backtick [ -i ] [ -n ] <em>variable</em> { <em>prog1...</em> } <em>prog2...</em>
</pre>
<ul>
<li> <tt>backtick</tt> reads <em>prog1...</em> in a
<a href="el_semicolon.html">block</a> and unquotes it. </li>
<li> It runs <em>prog1...</em> as a child process and saves its
output in memory. This output must not contain a null character. </li>
<li><tt>backtick</tt> execs into the modified <em>prog2...</em>, with
<em>variable</em> added to the environment with <em>prog1...</em>'s
output as a value. </li>
</ul>
<h2> Options </h2>
<ul>
<li> <tt>-i</tt> : insist. If <em>prog1</em> exits non-zero,
<tt>backtick</tt> exits with the same exit code (or 111 if <em>prog1</em>
crashed for some reason). Without this option, <tt>backtick</tt> execs into
<em>prog2...</em> no matter what <em>prog1</em> does, with the null word as
<em>variable</em>'s value if <em>prog1</em> didn't write anything before
dying. </li>
<li> <tt>-n</tt> : chomp an ending newline off <em>prog1...</em>'s
output. </li>
</ul>
<h2> Notes </h2>
<ul>
<li> You can start <em>prog2...</em> with "import <em>variable</em> unexport <em>variable</em>"
to perform variable substitution. </li>
</ul>
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</html>
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