PHP 4 >= 4.1.0, PHP 5, PHP 7, PHP 8
pcntl_signal - Installs a signal handler
Code Examples

pcntl_signal( int$signal, callable|int$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 signal.



The signal number.


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:

handler( int$signo, mixed$siginfo ): void

The signal being handled.


If operating systems supports siginfo_t structures, this will be an array of signal information dependent on the signal.


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.


Specifies whether system call restarting should be used when this signal arrives.

Return Values

Returns true on success or false on failure.


pcntl_signal doesn't stack the signal handlers, but replaces them.


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.

Related Functions

Example of pcntl_signal

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