Get filename of file which ran PHP include

An easy way is to assign a variable in the parent file (before the inclue), then reference that variable in the included file.

Parent File:

$myvar_not_replicated = __FILE__; // Make sure nothing else is going to overwrite
include 'other_file.php';

Included File:

if (isset($myvar_not_replicated)) echo "{$myvar_not_replicated} included me";
else echo "Unknown file included me";

You could also mess around with get_included_files() or debug_backtrace() and find the event when and where the file got included, but that can get a little messy and complicated.

Make sure you always include with an absolute path, like:

require_once(dirname(__FILE__) . "/otherfile.php");
require_once(dirname(__FILE__) . "/../uponefolder.php");
require_once(dirname(__FILE__) . "/sub/folder/file.php");

Or use autoloading.

You can't include php files relatively to your webroot that way, cause if you use the slash as first character, the reference will go much deeper than just your document root. So, instead of using your basepath, you could do something like this :

<?php 
   $path = $_SERVER['DOCUMENT_ROOT'];
   $path .= "/yourpath/yourfile.php";
   include_once($path);
?>