php man page for pcntl_signal

PCNTL_SIGNAL(3) 							 1							   PCNTL_SIGNAL(3)

pcntl_signal - Installs a signal handler

SYNOPSIS
       bool pcntl_signal (int  $signo, callable|int  $handler, [bool  $restart_syscalls = true])

DESCRIPTION
	The pcntl_signal(3) function installs a new signal handler or replaces the current signal handler for the signal indicated by $signo.

PARAMETERS
	      o $signo
		- The signal number.

	      o $handler
		-  The signal handler. This may be either a callable, which will be invoked to handle the signal, or either of the two global con-
		stants SIG_IGN or SIG_DFL, which will ignore the signal or restore the default signal handler  respectively.   If  a  callable	is
		given, it must implement the following signature:
		void handler (int  $signo)

		     o $signo
		       - The signal being handled.

	      Note

		      Note  that  when	you  set  a handler to an object method, that object's reference count is increased which makes it persist
		     until you either change the handler to something else, or your script ends.

	      o $restart_syscalls
		- Specifies whether system call restarting should be used when this signal arrives.

RETURN VALUES
	Returns TRUE on success or FALSE on failure.

CHANGELOG
       +--------+---------------------------------------------------+
       |Version |						    |
       |	|						    |
       |	|		     Description		    |
       |	|						    |
       +--------+---------------------------------------------------+
       | 4.3.0	|						    |
       |	|						    |
       |	|  As of PHP 4.3.0 PCNTL uses ticks as	the  signal |
       |	| handle  callback  mechanism, which is much faster |
       |	| than the previous mechanism. This change  follows |
       |	| the  same  semantics	as  using "user ticks". You |
       |	| must use the declare() statement to  specify	the |
       |	| locations  in  your  program	where callbacks are |
       |	| allowed to occur for the signal handler to  func- |
       |	| tion properly (as used in the example below).     |
       |	|						    |
       +--------+---------------------------------------------------+
EXAMPLES
       Example #1

	      pcntl_signal(3) example

	      <?php
	      // tick use required as of PHP 4.3.0
	      declare(ticks = 1);

	      // signal handler function
	      function sig_handler($signo)
	      {

		   switch ($signo) {
		       case SIGTERM:
			   // handle shutdown tasks
			   exit;
			   break;
		       case SIGHUP:
			   // handle restart tasks
			   break;
		       case SIGUSR1:
			   echo "Caught SIGUSR1...
";
			   break;
		       default:
			   // handle all other signals
		   }

	      }

	      echo "Installing signal handler...
";

	      // setup signal handlers
	      pcntl_signal(SIGTERM, "sig_handler");
	      pcntl_signal(SIGHUP,  "sig_handler");
	      pcntl_signal(SIGUSR1, "sig_handler");

	      // or use an object, available as of PHP 4.3.0
	      // pcntl_signal(SIGUSR1, array($obj, "do_something"));

	      echo"Generating signal SIGUSR1 to self...
";

	      // send SIGUSR1 to current process id
	      // posix_* functions require the posix extension
	      posix_kill(posix_getpid(), SIGUSR1);

	      echo "Done
";

	      ?>

NOTES
       pcntl_signal(3) doesn't stack the signal handlers, but replaces them.

SEE ALSO
       pcntl_fork(3), pcntl_waitpid(3).

PHP Documentation Group 													   PCNTL_SIGNAL(3)