[/
 / Copyright (c) 2003-2020 Christopher M. Kohlhoff (chris at kohlhoff dot com)
 /
 / Distributed under the Boost Software License, Version 1.0. (See accompanying
 / file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 /]

[section:signals Signal Handling]

Boost.Asio supports signal handling using a class called [link
boost_asio.reference.signal_set signal_set]. Programs may add one or more signals to
the set, and then perform an `async_wait()` operation. The specified handler
will be called when one of the signals occurs. The same signal number may be
registered with multiple [link boost_asio.reference.signal_set signal_set] objects,
however the signal number must be used only with Boost.Asio.

  void handler(
      const boost::system::error_code& error,
      int signal_number)
  {
    if (!error)
    {
      // A signal occurred.
    }
  }

  ...

  // Construct a signal set registered for process termination.
  boost::asio::signal_set signals(io_context, SIGINT, SIGTERM);

  // Start an asynchronous wait for one of the signals to occur.
  signals.async_wait(handler);

Signal handling also works on Windows, as the Microsoft Visual C++ runtime
library maps console events like Ctrl+C to the equivalent signal.

[heading See Also]

[link boost_asio.reference.signal_set signal_set],
[link boost_asio.examples.cpp03_examples.http_server HTTP server example (C++03)],
[link boost_asio.examples.cpp11_examples.http_server HTTP server example (C++11)].

[endsect]