(PHP 4 >= 4.1.0, PHP 5, PHP 7, PHP 8)
pcntl_signal — Installs a signal handler
The pcntl_signal() function installs a new
signal handler or replaces the current signal handler for the signal indicated by signal.
signalThe signal number.
handler
The signal handler. This may be either a callable, which
will be invoked to handle the signal, or either of the two global
constants 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:
signalsiginfoNote:
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.
restart_syscallsSpecifies whether system call restarting should be used when this signal arrives.
| Version | Description |
|---|---|
| 7.1.0 | As of PHP 7.1.0 the handler callback is given a second argument containing the siginfo of the specific signal. This data is only supplied if the operating system has the siginfo_t structure. If the OS does not implement siginfo_t NULL is supplied. |
Example #1 pcntl_signal() example
<?php
// tick use required
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
// pcntl_signal(SIGUSR1, array($obj, "do_something"));
echo"Generating signal SIGUSR1 to self...\n";
// send SIGUSR1 to current process id
// posix_* functions require the posix extension
posix_kill(posix_getpid(), SIGUSR1);
echo "Done\n";
?>pcntl_signal() doesn't stack the signal handlers, but replaces them.