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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | CONFORMING TO | NOTES | SEE ALSO | COLOPHON |
ALARM(2) Linux Programmer's Manual ALARM(2)
alarm - set an alarm clock for delivery of a signal
#include <unistd.h>
unsigned int alarm(unsigned int seconds);
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.
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.
POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.
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.
gettimeofday(2), pause(2), select(2), setitimer(2), sigaction(2),
signal(2), timer_create(2), timerfd_create(2), sleep(3), time(7)
This page is part of release 4.12 of the Linux man-pages project. A
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latest version of this page, can be found at
https://www.kernel.org/doc/man-pages/.
Linux 2017-05-03 ALARM(2)
Pages that refer to this page: tload(1), fork(2), getitimer(2), seccomp(2), signal(2), syscalls(2), sleep(3), ualarm(3), usleep(3), signal(7), signal-safety(7), time(7)