ALARM(3) BSD Library Functions Manual ALARM(3)
NAME
alarm -- set signal timer alarm
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <unistd.h>
unsigned int
alarm(unsigned int seconds);
DESCRIPTION
This interface is made obsolete by setitimer(2).
The alarm() function sets a timer to deliver the signal SIGALRM to the calling process seconds after the call to alarm(). If an alarm has
already been set with alarm() but has not been delivered, another call to alarm() will supersede the prior call. The request alarm(0) voids
the current alarm and the signal SIGALRM will not be delivered. The maximum number of seconds allowed is 2147483647.
The return value of alarm() is the amount of time left on the timer from a previous call to alarm(). If no alarm is currently set, the
return value is 0. If there is an error setting the timer, alarm() returns ((unsigned int) -1).
SEE ALSO
setitimer(2), sigaction(2), sigsuspend(2), signal(3), sigvec(3), sleep(3), ualarm(3), usleep(3)
STANDARDS
The alarm() function conforms to ISO/IEC 9945-1:1990 (``POSIX.1'').
HISTORY
An alarm() function appeared in Version 7 AT&T UNIX.
BSD
April 19, 1994 BSD
