alarm - set an alarm clock for delivery of a signal
unsigned int alarm(unsigned int seconds);
alarm arranges for a SIGALRM signal to be delivered to the
process in seconds seconds.
If seconds is zero, no new alarm is scheduled.
In any event any previously set alarm is cancelled.
alarm returns the number of seconds remaining until any
previously scheduled alarm was due to be delivered, or
zero if there was no previously scheduled alarm.
alarm and setitimer share the same timer; calls to one
will interfere with use of the other.
sleep() may be implemented using SIGALRM; mixing calls to
alarm() and sleep() is a bad idea.
Scheduling delays can, as ever, cause the execution of the
process to be delayed by an arbitrary amount of time.
SVr4, SVID, POSIX, X/OPEN, BSD 4.3
setitimer(2), signal(2), sigaction(2), gettimeofday(2),
select(2), pause(2), sleep(3)