alarm(2)                                                       alarm(2)

  alarm()

  NAME

    alarm() - set signal timer alarm

  SYNOPSIS

    #include 

    unsigned int alarm (unsigned int seconds)

  DESCRIPTION

    The alarm(2) function sets a countdown timer that waits seconds before
    asserting the terminating signal SIGALRM; alarm(2) returns immediately
    after setting the timer.

    If there is a pending alarm(2) request, the call to alarm(2) replaces the
    prior call. In this case, the alarm(2) function returns the number of
    seconds left on the prior call's timer.

    To cancel an alarm without setting a new one, pass 0 as the seconds
    argument.

    The maximum number of seconds allowed is the maximum value of an unsigned
    int.

  RETURN VALUE

    If there is no other alarm(2) request pending, alarm(2) returns 0 after
    setting the timer.

    If there is another alarm(2) request pending, alarm(2) returns the number
    of seconds remaining until the previous request would have generated a
    SIGALRM signal.

  SEE ALSO

    sigaction(2)

    signal(2)

    sleep(2)

  USAGE NOTES

    The alarm function is thread safe.

    The alarm function is async-signal safe.