PHP register_shutdown_function() Function

The PHP register_shutdown_function() function is used to register a function for execution on shutdown. The registered shutdown function is 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 exit() is called within one registered shutdown function, processing will stop completely and no other registered shutdown functions will be called.

Syntax

register_shutdown_function(callback, args)

Parameters

Return Value

No value is returned.

Exceptions

Generates a E_WARNING level error if the passed callback is not callable.

Example: register_shutdown_function() example

The example below shows the usage of register_shutdown_function() function.

<?php
//defining a shutdown function
function shutdown() {
  echo 'Script is executed successfully!'.PHP_EOL;
}

//registering the shutdown function
register_shutdown_function('shutdown');

//displaying some message
echo "Hello World!\n";
?>

The output of the above code will be similar to:

Hello World!
Script is executed successfully!

Example: register_shutdown_function() example

In the example below the shutdown function is used to display message based on connection status.

<?php
//defining a shutdown function
function shutdown() {
  if(connection_status() == CONNECTION_TIMEOUT) {
     print 'Script timeout!'.PHP_EOL;
  } else {
     print 'Script is executed successfully!'.PHP_EOL;
  }
}

//registering the shutdown function
register_shutdown_function('shutdown');

//displaying some message
echo "Hello World!\n";
?>

The output of the above code will be similar to:

Hello World!
Script is executed successfully!

Example: using args parameter

Consider one more example, where this function is used to pass an additional parameter to the shutdown function.

<?php
//defining a shutdown function
function shutdown($user) {
  if(connection_status() == CONNECTION_TIMEOUT) {
     print "Script timeout!".PHP_EOL;
  } else {
     print "Goodbye $user!".PHP_EOL;
  }
}

$user = "John";

//registering the shutdown function
register_shutdown_function('shutdown', $user);

//displaying some message
echo "Hello $user!\n";
?>

The output of the above code will be similar to:

Hello John!
Goodbye John!