Mine

<?php

define('PAGES_PATH', 'pages'); //this is set from config file
define('PLUGINS_PATH', 'plugins'); 

//Include here footer 
//include navigation

if (is_dir(PAGES_PATH)) {
	//echo 'Olemas';
	$file_php = PAGES_PATH .'/page_'. $_GET['action'] .'.php';
	$file_plugin = PLUGINS_PATH .'/plugin_'. $_GET['action'] .'.php';
	
	if (file_exists($file_php)) {
		include($file_php);
	} else if (file_exists($file_plugin)) {	
		include($file_plugin);
	} else {
		echo 'There is no such page !';
	}
}


//include here header
?>