signal.h

who here has experience with signal.h? I need some help with it...I have searched through the documentation of signal.h and asked some people about it, but so far no luck. I need some help understanding what exactly this code does:

Code:

//i know what this does:
static int done = 0;
void poked(int sig)
{
	done = 1;
}

//more code

.....code.....

//its this part i dont understand:

#ifdef SIGHUP
	signal(SIGHUP, poked);
#endif
	signal(SIGINT, poked);
#ifdef SIGQUIT
	signal(SIGQUIT, poked);
#endif
	signal(SIGTERM, poked);

Anybody have experience with the signal function (in signal.h)? Thanx.

http://www.dinkumware.com/htm_cpl/signal.html