freebsd man page for alarm

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 after the specified 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), sigsuspend(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