Linux man pages : alarm (2)
ALARM(2) Linux Programmer's Manual ALARM(2)
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
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 previ-
ously 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),
Linux 1993-07-21 ALARM(2)