doc/background.html


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<p>
<a href="index.html">execline</a><br />
<a href="//skarnet.org/software/">Software</a><br />
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<h1> The <tt>&amp;</tt> program </h1>

<tt>&amp;</tt> launches a command in the background, then goes on
with the execution flow.

<h2> Interface </h2>

<p>
 In an <a href="execlineb.html">execlineb</a> script:
</p>

<pre>
     &amp; [ -d ] { <em>prog1...</em> } <em>prog2...</em>
</pre>

<ul>
 <li> <tt>&amp;</tt> reads a <em>prog1...</em> command in a
<a href="el_semicolon.html">block</a> and unquotes it. </li>
 <li> It spawns a child executing <em>prog1...</em>. </li>
 <li> It sets the <tt>!</tt> environment
variable to the pid of the <em>prog1...</em> process. </li>
 <li> It then execs into <em>prog2...</em>. </li>
</ul>

<h2> Options </h2>

<ul>
 <li> <tt>-d</tt>&nbsp;: doublefork. If the <tt>-d</tt> option is set,
<em>prog1...</em> will run as a grandchild of <tt>&amp;</tt>. </li>
</ul>

<h2> Notes </h2>

<ul>
 <li> <tt>&amp; <em>prog1...</em> "" <em>prog2...</em></tt> is
equivalent to <tt>sh -c '<em>prog1...</em> & ; exec <em>prog2...</em>'</tt>. </li>
</ul>

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