ultrix man page for alarm

alarm(3)						     Library Functions Manual							  alarm(3)

Name
       alarm - schedule signal after specified time

Syntax
       #include <unistd.h>

       unsigned alarm(seconds)
       unsigned seconds;

Description
       The  subroutine	causes signal SIGALRM, see to be sent to the invoking process in a number of seconds given by the argument.  Unless caught
       or ignored, the signal terminates the process.

       The requests are not stacked.  Successive calls reset the alarm clock.  If the argument is 0, any request is canceled.  Because of schedul-
       ing delays, resumption of execution of when the signal is caught may be delayed an arbitrary amount.  The longest specifiable delay time is
       100000000 seconds. Values larger than 100000000 will be silently rounded down to 100000000.

       The return value is the amount of time previously remaining in the alarm clock.

Environment
       When your program is compiled using the System V environment, rounds up any positive fraction of a second to the next second.

       When your program is compiled using the POSIX environment, takes a parameter of type unsigned, and returns a value of type unsigned.

See Also
       getitimer(2), sigpause(2), sigvec(2), signal(3), sleep(3)

																	  alarm(3)