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<title>s6: the s6-fdholder-store program</title>
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<h1> The <tt>s6-fdholder-store</tt> program </h1>
<p>
<tt>s6-fdholder-store</tt> connects to a
<a href="s6-fdholderd.html">fd-holding daemon</a> listening on a
Unix domain socket, and gives it a copy of one of its open file
descriptors for the daemon to hold.
</p>
<h2> Interface </h2>
<pre>
s6-fdholder-store [ -d <em>fd</em> ] [ -T fdtimeout ] [ -t <em>timeout</em> ] <em>path</em> <em>id</em>
</pre>
<ul>
<li> <tt>s6-fdholder-store</tt> connects to a
<a href="s6-fdholderd.html">s6-fdholderd</a> server process listening on
<em>path</em>. </li>
<li> It attempts to pass a copy of its standard input, or of its descriptor
<em>fd</em>, to the server, with identifier <em>id</em>. </li>
</ul>
<h2> Options </h2>
<ul>
<li> <tt>-d <em>fd</em></tt> : store descriptor number <em>fd</em>.
By default, <em>fd</em> is 0 (i.e. the program's stdin will be stored). </li>
<li> <tt>-T <em>fdtimeout</em></tt> : the descriptor is stored with
an expiration time of <em>fdtimeout</em> milliseconds, which means the
<a href="s6-fdholderd.html">s6-fdholderd</a> daemon will close and get rid of
the descriptor after this time. By default, <em>fdtimeout</em> is 0, which
means infinite - no expiration time. </li>
<li> <tt>-t <em>timeout</em></tt> : if the operation cannot be
processed in <em>timeout</em> milliseconds, then fail with an error message.
Communications with the server should be near-instant, so this option is
only here to protect users against programming errors (connecting to the
wrong socket, for instance). </li>
</ul>
<h2> Exit codes </h2>
<ul>
<li> 0: success. </li>
<li> 1: the server denied the operation. The meaning of the error messages
is explained <a href="s6-fdholder-errorcodes.html">here</a>. </li>
<li> 100: wrong usage. </li>
<li> 111: system call failed - this includes attempting to connect to a
nonexistent socket, or one where no <a href="s6-fdholderd.html">s6-fdholderd</a>
daemon is listening. </li>
</ul>
<h2> Usage example </h2>
<pre>
<a href="s6-ipcserver-socketbinder.html">s6-ipcserver-socketbinder</a> /tmp/mysocket s6-fdholder-store /service/fdholderd/s MYSOCKET
</pre>
<p>
will open a Unix domain socket, bind it to <tt>/tmp/mysocket</tt> and
listen to incoming connections, then give it to a
<a href="s6-fdholderd.html">s6-fdholderd</a> instance listening on
<tt>/service/fdholderd/s</tt>, with no expiration date, with the
"MYSOCKET" identifier. Another program will be able to retrieve the
socket later, using <a href="s6-fdholder-retrieve.html">s6-fdholder-retrieve</a>.
</p>
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