Introduction:
This library lets you associate a unix signal with a file descriptor
and have the file descriptor ready for reading whenever an associated unix signal arrives.
This ability lets you multiplex unix signals just like file descriptors.
This library also extends boost::asio with the ability to invoke a handler whenever a unix signal arrives.

Online documentation is available here http://dgoncharov.github.com/libunixsignal.

Motivation:
The library lets the user have a unix signal handler of an arbitrary signature. 
The library also removes the "async-signal safe calls" restriction from a handler of a unix signal. 

Contents:
This is a header only library. The library contains two files signalfd.hpp and signal_handler.hpp.
signalfd.hpp defines class template signalfd.
example/sigselect.cpp contains an example of how signalfd is supposed to be used.
signal_handler.hpp contains class template signal_hander which is an extension to boost::asio.
example/sighandler.cpp contains an example of how signal_handler is supposed to be used.

How to install:
Since this is a header only library there is no need to compile it.
Type ./configure; make install to install the library.
This will create the directory unixsignal/ and place signalfd.hpp and signal_handler.hpp in it.
By default the directory unixsignal gets created in /usr/local/include.
Type make uninstall to remove the library installed header files.
Type make sample to build the samples.
This will build sigselect from example/sigselect.cpp and sighandler from example/sighandler.cpp.
You can run the examples by typing example/sigselect or example/sighandler.
Type make check to run the unit test.
Type make info, make html or make pdf to build the texinfo, html or pdf documentation.

The original proposal on the boost mail list can be found here http://lists.boost.org/Archives/boost/2009/03/149890.php

Tested on
-amd64 freebsd 7.2 gcc-4.1.2.
-x86_64 linux 2.6.30-gentoo-r4 gcc-4.4.1, 2.6.32-gentoo gcc-4.4.2, 2.6.33-gentoo gcc-4.4.3.
-i686 linux 2.6.31-gentoo gcc-4.4.1, 2.6.32-gentoo gcc-4.4.3, 2.6.33-gentoo gcc-4.4.3.