ALARM(3) | Library Functions Manual | ALARM(3) |
alarm
— schedule
SIGALRM delivery
#include
<unistd.h>
unsigned int
alarm
(unsigned
int seconds);
The
alarm
()
function schedules the SIGALRM
signal for delivery
to the calling process after the given number of
seconds have elapsed.
If an alarm is already pending, another call to
alarm
()
will supersede the prior call.
If seconds is zero, any pending alarm is cancelled.
alarm
() returns the number of seconds
remaining until the pending alarm would have expired. If the alarm has
already expired, the alarm was cancelled, or no alarm was ever scheduled,
alarm
() returns zero.
setitimer(2), sigaction(2), sigsuspend(2), signal(3), sleep(3), ualarm(3)
The alarm
() function conforms to
IEEE Std 1003.1-2008 (“POSIX.1”).
An alarm
() system call appeared in the
Programmer's Workbench (PWB/UNIX) and was ported to
Version 7 AT&T UNIX. For
4.1cBSD, it was reimplemented as a wrapper around
the setitimer(2) system call.
The alarm
() function is implemented with
the per-process ITIMER_REAL
timer described in
setitimer(2). Use of both
alarm
() and
setitimer(2) in the same program may
yield confusing behavior.
June 18, 2021 | OpenBSD-current |