pcntl_signal
(PHP 4 >= 4.1.0)
pcntl_signal -- Installs a signal handler
Description
bool pcntl_signal ( int signo, callback handle [, bool restart_syscalls])
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).
See also pcntl_fork() and pcntl_waitpid().
