signal

http://en.wikipedia.org/wiki/Signal_(computing)

http://osiris.978.org/~alex/safesignalhandling.html

http://users.evtek.fi/~tk/rtp/signals-programming.html

http://publib.boulder.ibm.com/infocenter/pseries/v5r3/index.jsp?topic=/com.ibm.aix.basetechref/doc/basetrf2/sigaction.htm