alarm - schedule signal after specified time
unsigned int alarm(unsigned int seconds)
Alarm causes signal SIGALRM, see sigaction(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 return value is the amount of time previously remaining in the alarm
pause(2), sigsuspend(2), sigaction(2), sleep(3).