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<h1>luaposix 33.3.0</h1>
<ul>
<li><a href="../index.html">Index</a></li>
</ul>
<h2>Contents</h2>
<ul>
<li><a href="#Functions">Functions</a></li>
</ul>
<h2>Modules</h2>
<ul class="$(kind=='Topics' and '' or 'nowrap'">
<li><a href="../modules/posix.html">posix</a></li>
<li><a href="../modules/posix.ctype.html">posix.ctype</a></li>
<li><a href="../modules/posix.curses.html">posix.curses</a></li>
<li><a href="../modules/posix.dirent.html">posix.dirent</a></li>
<li><a href="../modules/posix.errno.html">posix.errno</a></li>
<li><a href="../modules/posix.fcntl.html">posix.fcntl</a></li>
<li><a href="../modules/posix.fnmatch.html">posix.fnmatch</a></li>
<li><a href="../modules/posix.getopt.html">posix.getopt</a></li>
<li><a href="../modules/posix.glob.html">posix.glob</a></li>
<li><a href="../modules/posix.grp.html">posix.grp</a></li>
<li><a href="../modules/posix.libgen.html">posix.libgen</a></li>
<li><strong>posix.poll</strong></li>
<li><a href="../modules/posix.pwd.html">posix.pwd</a></li>
<li><a href="../modules/posix.sched.html">posix.sched</a></li>
<li><a href="../modules/posix.signal.html">posix.signal</a></li>
<li><a href="../modules/posix.stdio.html">posix.stdio</a></li>
<li><a href="../modules/posix.stdlib.html">posix.stdlib</a></li>
<li><a href="../modules/posix.sys.msg.html">posix.sys.msg</a></li>
<li><a href="../modules/posix.sys.resource.html">posix.sys.resource</a></li>
<li><a href="../modules/posix.sys.socket.html">posix.sys.socket</a></li>
<li><a href="../modules/posix.sys.stat.html">posix.sys.stat</a></li>
<li><a href="../modules/posix.sys.statvfs.html">posix.sys.statvfs</a></li>
<li><a href="../modules/posix.sys.time.html">posix.sys.time</a></li>
<li><a href="../modules/posix.sys.times.html">posix.sys.times</a></li>
<li><a href="../modules/posix.sys.utsname.html">posix.sys.utsname</a></li>
<li><a href="../modules/posix.sys.wait.html">posix.sys.wait</a></li>
<li><a href="../modules/posix.syslog.html">posix.syslog</a></li>
<li><a href="../modules/posix.termio.html">posix.termio</a></li>
<li><a href="../modules/posix.time.html">posix.time</a></li>
<li><a href="../modules/posix.unistd.html">posix.unistd</a></li>
<li><a href="../modules/posix.utime.html">posix.utime</a></li>
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<h2>Classes</h2>
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<li><a href="../classes/posix.curses.chstr.html">posix.curses.chstr</a></li>
<li><a href="../classes/posix.curses.window.html">posix.curses.window</a></li>
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<h2>Examples</h2>
<ul class="$(kind=='Topics' and '' or 'nowrap'">
<li><a href="../examples/curses.lua.html">curses.lua</a></li>
<li><a href="../examples/dir.lua.html">dir.lua</a></li>
<li><a href="../examples/fork.lua.html">fork.lua</a></li>
<li><a href="../examples/fork2.lua.html">fork2.lua</a></li>
<li><a href="../examples/getopt.lua.html">getopt.lua</a></li>
<li><a href="../examples/glob.lua.html">glob.lua</a></li>
<li><a href="../examples/limit.lua.html">limit.lua</a></li>
<li><a href="../examples/lock.lua.html">lock.lua</a></li>
<li><a href="../examples/netlink-uevent.lua.html">netlink-uevent.lua</a></li>
<li><a href="../examples/ping.lua.html">ping.lua</a></li>
<li><a href="../examples/poll.lua.html">poll.lua</a></li>
<li><a href="../examples/rt_sched.lua.html">rt_sched.lua</a></li>
<li><a href="../examples/signal.lua.html">signal.lua</a></li>
<li><a href="../examples/socket.lua.html">socket.lua</a></li>
<li><a href="../examples/termios.lua.html">termios.lua</a></li>
<li><a href="../examples/tree.lua.html">tree.lua</a></li>
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<div id="content">
<h1>Module <code>posix.poll</code></h1>
<p>Synchronous I/O Multiplexing.</p>
<p> Examine file descriptors for events, such as readyness for I/O.</p>
<h2><a href="#Functions">Functions</a></h2>
<table class="function_list">
<tr>
<td class="name" nowrap><a href="#poll">poll (fds[, timeout=-1])</a></td>
<td class="summary">Wait for events on multiple file descriptors.</td>
</tr>
<tr>
<td class="name" nowrap><a href="#rpoll">rpoll (fd[, timeout=-1])</a></td>
<td class="summary">Wait for some event on a file descriptor.</td>
</tr>
</table>
<br/>
<br/>
<h2><a name="Functions"></a>Functions</h2>
<dl class="function">
<dt>
<a name = "poll"></a>
<strong>poll (fds[, timeout=-1])</strong>
</dt>
<dd>
Wait for events on multiple file descriptors.
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">fds</span>
<span class="types"><a class="type" href="http://www.lua.org/manual/5.1/manual.html#5.5">table</a></span>
list of file descriptors
</li>
<li><span class="parameter">timeout</span>
<span class="types"><span class="type">int</span></span>
maximum timeout in milliseconds, or -1 to block indefinitely
(<em>default</em> -1)
</li>
</ul>
<h3>Returns:</h3>
<ol>
<span class="types"><span class="type">int</span></span>
0 if timed out, 1 if <em>fd</em> is ready
</ol>
<h3>Or</h3>
<ol>
<li>
nil</li>
<li>
<span class="types"><a class="type" href="http://www.lua.org/manual/5.1/manual.html#5.4">string</a></span>
error message</li>
<li>
<span class="types"><span class="type">int</span></span>
errnum</li>
</ol>
<h3>See also:</h3>
<ul>
<li><a href="http://pubs.opengroup.org/onlinepubs/009695399/functions/poll.html">poll(2)</a></li>
<li><a href="../modules/posix.poll.html#rpoll">rpoll</a></li>
<li><a href="../examples/poll.lua.html#">poll.lua</a></li>
</ul>
</dd>
<dt>
<a name = "rpoll"></a>
<strong>rpoll (fd[, timeout=-1])</strong>
</dt>
<dd>
Wait for some event on a file descriptor.
Based on <a href="">http://lua-users.org/lists/lua-l/2007-11/msg00346.html</a>.
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">fd</span>
<span class="types"><span class="type">int</span></span>
file descriptor
</li>
<li><span class="parameter">timeout</span>
<span class="types"><span class="type">int</span></span>
maximum timeout in milliseconds, or -1 to block indefinitely
(<em>default</em> -1)
</li>
</ul>
<h3>Returns:</h3>
<ol>
<span class="types"><span class="type">int</span></span>
0 if timed out, 1 if <em>fd</em> is ready
</ol>
<h3>Or</h3>
<ol>
<li>
nil</li>
<li>
error message</li>
<li>
<span class="types"><span class="type">int</span></span>
errnum</li>
</ol>
<h3>See also:</h3>
<ul>
<a href="../modules/posix.poll.html"></a>
</ul>
<h3>Usage:</h3>
<ul>
<pre class="example">
fh = <span class="global">io</span>.open <span class="string">"one"</span>
<span class="keyword">while</span> <span class="keyword">true</span> <span class="keyword">do</span>
r = rpoll (fh, <span class="number">500</span>)
<span class="keyword">if</span> r == <span class="number">0</span> <span class="keyword">then</span>
<span class="global">print</span> <span class="string">'timeout'</span>
<span class="keyword">elseif</span> r == <span class="number">1</span> <span class="keyword">then</span>
<span class="global">print</span> (fh:read ())
<span class="keyword">else</span>
<span class="global">print</span> <span class="string">"finish!"</span>
<span class="keyword">break</span>
<span class="keyword">end</span>
<span class="keyword">end</span></pre>
</ul>
</dd>
</dl>
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