alarm(2) - Linux man page

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 calling process in seconds seconds.

If seconds is zero, no new alarm() is scheduled.

In any event any previously set alarm() is canceled.

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 previously scheduled alarm.

Conforming to

SVr4, POSIX.1-2001, 4.3BSD.

Notes

alarm() and setitimer(2) share the same timer; calls to one will interfere with use of the other.

sleep(3) may be implemented using SIGALRM; mixing calls to alarm() and sleep(3) is a bad idea.

Scheduling delays can, as ever, cause the execution of the process to be delayed by an arbitrary amount of time.

See Also

gettimeofday(2), pause(2), select(2), setitimer(2), sigaction(2), signal(2), sleep(3), time(7)

Referenced By

fork(2), getitimer(2), objcmdwrite(3), snmp_alarm(3), tload(1), ualarm(3), usleep(3)