Timers delivering signals

So far, we've seen just about all there is to see with timers, except for one small thing. We've been delivering messages (via a pulse), but you can also deliver POSIX signals. Let's see how this is done:

timer_create (CLOCK_REALTIME, NULL, &timerid);

This is the simplest way to create a timer that sends you a signal. This method raises SIGALRM when the timer fires. If we had actually supplied a struct sigevent, we could specify which signal we actually want to get:

struct sigevent event;

timer_create (CLOCK_REALTIME, &event, &timerid);

This hits us with SIGUSR1 instead of SIGALRM.

You catch timer signals with normal signal handlers; there's nothing special about them.