ALARM
Section: Linux Programmer's Manual (2)
Updated: 2017-05-03
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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.
CONFORMING TO
POSIX.1-2001, POSIX.1-2008, SVr4, 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),
timer_create(2),
timerfd_create(2),
sleep(3),
time(7)
COLOPHON
This page is part of release 4.13 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
https://www.kernel.org/doc/man-pages/.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- CONFORMING TO
-
- NOTES
-
- SEE ALSO
-
- COLOPHON
-
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