Determine the server and web directory of the current file.

set_app_path.php

<?php
/**
 * set the server directory that this application is stored in.
 * if applicaiton is in the root directory, set to "/"
 */

$_app_server_path = rtrim(str_replace('\\', '/', dirname(__FILE__)),"/")."/"; // eg: "/home/ubuntu/workspace/my-website/"

$web_app_path = str_replace(rtrim($_SERVER['DOCUMENT_ROOT'],"/"),'',$_app_server_path); // eg: "/my-website/" or just "/" if in root

define('_app_path',$web_app_path); 
define('_app_server_path',$_app_server_path);