Php/docs/function.pcntl-signal
pcntl_signal
(PHP 4 >= 4.1.0, PHP 5, PHP 7)
pcntl_signal — Installs a signal handler
Description
pcntl_signal
( int $signo
, callable|int $handler
[, bool $restart_syscalls
= TRUE
] ) : bool
The pcntl_signal() function installs a new
signal handler or replaces the current signal handler for the signal indicated by signo
.
Parameters
signo
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
orSIG_DFL
, which will ignore the signal or restore the default signal handler respectively.If a callable is given, it must implement the following signature:
handler ( int
$signo
, mixed$signinfo
) : voidsigno
- 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.
Changelog
Version | Description |
---|---|
7.1.0 | As of PHP 7.1.0 the handler callback is given a second argument
containing the signinfo of the specific signal. This data is only supplied if the operating system has the signinfo_t structure. If the OS does not implement siginfo_t NULL is supplied. |
Examples
Example #1 pcntl_signal() example
<?php// tick use requireddeclare(ticks = 1);// signal handler functionfunction 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 handlerspcntl_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 extensionposix_kill(posix_getpid(), SIGUSR1);echo "Done\n";?>
Notes
pcntl_signal() doesn't stack the signal handlers, but replaces them.
See Also
- pcntl_fork() - Forks the currently running process
- pcntl_waitpid() - Waits on or returns the status of a forked child