This document is a Mac OS X manual page. Manual pages are a command-line technology for providing documentation. You can view these manual pages locally using the man(1) command. These manual pages come from many different sources, and thus, have a variety of writing styles.

For more information about the manual page format, see the manual page for manpages(5).

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
     alarm(unsigned 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 after the speci-fied specified
     fied number of seconds.  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.

     Due to setitimer(2) restriction the maximum number of seconds allowed is 100000000.

RETURN VALUES
     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.

SEE ALSO
     setitimer(2), sigaction(2), sigpause(2), sigvec(2), signal(3), sleep(3), ualarm(3), usleep(3)

HISTORY
     An alarm() function appeared in Version 7 AT&T UNIX.

BSD                             April 19, 1994                             BSD