pcntl_signal
Installs a signal handler
Description
bool pcntl_signal(int $signal
, callableint $handler
, bool $restart_syscalls
= true
)
Parameters
-
signal
-
The 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:
void handler(int $signo
, mixed $siginfo
)
-
signal
-
The signal being handled.
-
siginfo
-
If operating systems supports siginfo_t structures, this will be an array of signal information dependent on the signal.
Note:
Note that when you set a handler to an object method, that object's
reference count is increased which makes it persist until you either
change the handler to something else, or your script ends.
-
restart_syscalls
-
Specifies whether system call restarting should be used when this
signal arrives.
Return Values
Returns true
on success or false
on failure.
Examples
Example #1 pcntl_signal example
<?php
// tick use required
declare(ticks = 1);
// signal handler function
function sig_handler($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";
?>
Notes
pcntl_signal doesn't stack the signal handlers, but replaces them.