register_shutdown_function

(PHP 4, PHP 5, PHP 7, PHP 8)

register_shutdown_function — Register a function for execution on shutdown

Description

register_shutdown_function(callable $callback, mixed ...$args): ?bool

Registers a callback to be executed after script execution finishes or exit() is called.

Multiple calls to register_shutdown_function() can be made, and each will be called in the same order as they were registered. If you call exit() within one registered shutdown function, processing will stop completely and no other registered shutdown functions will be called.

Shutdown functions may also call register_shutdown_function() themselves to add a shutdown function to the end of the queue.

Parameters

callback

The shutdown callback to register.

The shutdown callbacks are executed as the part of the request, so it's possible to send output from them and access output buffers.

args

It is possible to pass parameters to the shutdown function by passing additional parameters.

Return Values

No value is returned.

Errors/Exceptions

If the passed callback is not callable a E_WARNING level error will be generated.

Examples

Example #1 register_shutdown_function() example


<?php
function shutdown()
{
    // This is our shutdown function, in 
    // here we can do any last operations
    // before the script is complete.

    echo 'Script executed with success', PHP_EOL;
}

register_shutdown_function('shutdown');
?>

Notes

Note:
The working directory of the script can change inside the shutdown function under some web servers, e.g. Apache.

Note:
Shutdown functions will not be executed if the process is killed with a SIGTERM or SIGKILL signal. While you cannot intercept a SIGKILL, you can use pcntl_signal() to install a handler for a SIGTERM which uses exit() to end cleanly.

Note:
Shutdown functions run separately from the time tracked by max_execution_time. That means even if a process is terminated for running too long, shutdown functions will still be called. Additionally, if the max_execution_time runs out while a shutdown function is running it will not be terminated.