Can an included PHP file know where it was included from?

Question

For example,

This is index.php

Can header.php know it was included by index.php?

Answer 1

$_SERVER['PHP_SELF'] should still point to file originally accessed, or you could set a variable before the require, eg:

$section = 'home';
require_once('header.php');

...

if ($section == 'home') {
    ...
}