The pcntl_signal() function installs a new
signal handler for the signal indicated by
signo. The signal handler is set to
handler which may be the name of a user
created function, or either of the two global constants SIG_IGN
or SIG_DFL. The optional restart_syscalls
specifies whether system call restarting should be used when this
signal arrives and defaults to TRUE.
Returns TRUE on success or FALSE on failure.
Note:
The optional restart_syscalls parameter became
available in PHP 4.3.0.
Note:
The ability to use an object method as a callback became available in
PHP 4.3.0. 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.
Example 1. pcntl_signal() 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...\n"; break; default: // handle all other signals }
}
echo "Installing signal handler...\n";
// 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 SIGTERM to self...\n";
// send SIGUSR1 to current process id posix_kill(posix_getpid(), SIGUSR1);
echo "Done\n"
?>
Note:
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 function properly (as used in
the above example).
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