

          alarm seconds
               Instructs the system to send a SIGALRM signal in the
               specified number of seconds.  This is a floating point
               number, so fractions of a section may be specified.  If
               seconds is 0.0, any previous alarm request is canceled.
               Only one alarm at a time may be active; the command
               returns the number of seconds left in the previous
               alarm.  On systems without the setitimer system call,
               seconds is rounded up to an even number of seconds.
