Linux
2017-05-03
manpages-dev
Manual pages about using GNU/Linux for development
man-pages
Linux kernel and C library user-space interface documentation
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).
Scheduling delays can, as ever, cause the execution of the process to be delayed by an arbitrary amount of time.
SEE ALSO
COLOPHON
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