alarm - schedule signal after specified time

unsigned seconds;

This interface is made obsolete by setitimer(2).

Alarm causes signal SIGALRM, see sigvec(2), 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.

Alarm requests are not stacked; successive calls reset the alarm
clock. If the argument is 0, any alarm request is canceled.
Because of scheduling delays, resumption of execution of when the
signal is caught may be delayed an arbitrary amount. The longest
specifiable delay time is 2147483647 seconds.

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

sigpause(2), sigvec(2), signal(3), sleep(3), ualarm(3), usleep(3)