ALARM(2) Linux Programmer s Manual ALARM(2)
NAME alarm - set an alarm clock for delivery of a signal
SYNOPSIS #include <unistd.h>
unsigned int alarm(unsigned int seconds);
DESCRIPTION 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.
RETURN VALUE 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.
NOTES alarm() and setitimer() share the same timer; calls to one will inter- fere 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.
CONFORMING TO SVr4, POSIX.1-2001, 4.3BSD
SEE ALSO gettimeofday(2), pause(2), select(2), setitimer(2), sigaction(2), sig- nal(2), sleep(3)
Linux 1993-07-21 ALARM(2)