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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968" /><title>sys_flock</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><link rel="home" href="index.html" title="Linux Filesystems API" /><link rel="up" href="ch01s05.html" title="File Locks" /><link rel="prev" href="re70.html" title="fcntl_setlease" /><link rel="next" href="ch01s06.html" title="Other Functions" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><span>sys_flock</span></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="re70.html">Prev</a> </td><th width="60%" align="center">File Locks</th><td width="20%" align="right"> <a accesskey="n" href="ch01s06.html">Next</a></td></tr></table><hr /></div><div class="refentry" title="sys_flock"><a id="API-sys-flock"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>sys_flock —
<code class="function">flock</code> system call.
</p></div><div class="refsynopsisdiv" title="Synopsis"><h2>Synopsis</h2><div class="funcsynopsis"><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">long <b class="fsfunc">sys_flock </b>(</code></td><td>unsigned int <var class="pdparam">fd</var>, </td></tr><tr><td> </td><td>unsigned int <var class="pdparam">cmd</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1" title="Arguments"><a id="id3106820"></a><h2>Arguments</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>fd</code></em></span></dt><dd><p>
the file descriptor to lock.
</p></dd><dt><span class="term"><em class="parameter"><code>cmd</code></em></span></dt><dd><p>
the type of lock to apply.
</p></dd></dl></div></div><div class="refsect1" title="Description"><a id="id3106863"></a><h2>Description</h2><p>
Apply a <code class="constant">FL_FLOCK</code> style lock to an open file descriptor.
The <em class="parameter"><code>cmd</code></em> can be one of
</p><p>
<code class="constant">LOCK_SH</code> -- a shared lock.
</p><p>
<code class="constant">LOCK_EX</code> -- an exclusive lock.
</p><p>
<code class="constant">LOCK_UN</code> -- remove an existing lock.
</p><p>
<code class="constant">LOCK_MAND</code> -- a `mandatory' flock. This exists to emulate Windows Share Modes.
</p><p>
<code class="constant">LOCK_MAND</code> can be combined with <code class="constant">LOCK_READ</code> or <code class="constant">LOCK_WRITE</code> to allow other
processes read and write access respectively.
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