(PHP 4 >= 4.3.0, PHP 5)
pcntl_alarm — Set an alarm clock for delivery of a signal
$seconds
   )
   Creates a timer that will send a SIGALRM signal to
   the process after the given number of seconds.
   Any call to pcntl_alarm() will cancel any previously
   set alarm.
  
seconds
       The number of seconds to wait. If seconds is
       zero, no new alarm is created.
      
Returns the time in seconds that any previously scheduled alarm had remaining before it was to be delivered, or 0 if there was no previously scheduled alarm.