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<div class="titlepage"><div><div><h3 class="title">
<a name="asio.overview.signals"></a><a class="link" href="signals.html" title="Signal Handling">Signal Handling</a>
</h3></div></div></div>
<p>
        Asio supports signal handling using a class called <a class="link" href="../reference/signal_set.html" title="signal_set">signal_set</a>.
        Programs may add one or more signals to the set, and then perform an <code class="computeroutput"><span class="identifier">async_wait</span><span class="special">()</span></code>
        operation. The specified handler will be called when one of the signals occurs.
        The same signal number may be registered with multiple <a class="link" href="../reference/signal_set.html" title="signal_set">signal_set</a>
        objects, however the signal number must be used only with Asio.
      </p>
<pre class="programlisting"><span class="keyword">void</span> <span class="identifier">handler</span><span class="special">(</span>
    <span class="keyword">const</span> <span class="identifier">asio</span><span class="special">::</span><span class="identifier">error_code</span><span class="special">&amp;</span> <span class="identifier">error</span><span class="special">,</span>
    <span class="keyword">int</span> <span class="identifier">signal_number</span><span class="special">)</span>
<span class="special">{</span>
  <span class="keyword">if</span> <span class="special">(!</span><span class="identifier">error</span><span class="special">)</span>
  <span class="special">{</span>
    <span class="comment">// A signal occurred.</span>
  <span class="special">}</span>
<span class="special">}</span>

<span class="special">...</span>

<span class="comment">// Construct a signal set registered for process termination.</span>
<span class="identifier">asio</span><span class="special">::</span><span class="identifier">signal_set</span> <span class="identifier">signals</span><span class="special">(</span><span class="identifier">io_service</span><span class="special">,</span> <span class="identifier">SIGINT</span><span class="special">,</span> <span class="identifier">SIGTERM</span><span class="special">);</span>

<span class="comment">// Start an asynchronous wait for one of the signals to occur.</span>
<span class="identifier">signals</span><span class="special">.</span><span class="identifier">async_wait</span><span class="special">(</span><span class="identifier">handler</span><span class="special">);</span>
</pre>
<p>
        Signal handling also works on Windows, as the Microsoft Visual C++ runtime
        library maps console events like Ctrl+C to the equivalent signal.
      </p>
<h5>
<a name="asio.overview.signals.h0"></a>
        <span><a name="asio.overview.signals.see_also"></a></span><a class="link" href="signals.html#asio.overview.signals.see_also">See
        Also</a>
      </h5>
<p>
        <a class="link" href="../reference/signal_set.html" title="signal_set">signal_set</a>, <a class="link" href="../examples/cpp03_examples.html#asio.examples.cpp03_examples.http_server">HTTP
        server example (C++03)</a>, <a class="link" href="../examples/cpp11_examples.html#asio.examples.cpp11_examples.http_server">HTTP
        server example (C++11)</a>.
      </p>
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<td align="right"><div class="copyright-footer">Copyright &#169; 2003-2014 Christopher M. Kohlhoff<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
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