As of PHP5, this function seems to return an array with the first index being the script all subsequent scripts are included to.If index.php includes b.php and c.php and calls get_included_files(), the returned array looks as follows:index.phpa.phpb.phpwhile in PHP<5 the array would be:a.phpb.phpIf you want to know which is the script that is including current script you can use $_SERVER['SCRIPT_FILENAME'] or any other similar server global.If you also want to ensure current script is being included and not run independently you should evaluate following expression:__FILE__ != $_SERVER['SCRIPT_FILENAME']If this expression returns TRUE, current script is being included or required.