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, any pending alarm is canceled.
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.
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.
Alarms created by
alarm() are preserved across
execve(2) and are
not inherited by children created via
fork(2).
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)
COLOPHON¶
This page is part of release 3.74 of the Linux
man-pages project. A
description of the project, information about reporting bugs, and the latest
version of this page, can be found at
http://www.kernel.org/doc/man-pages/.
