echo ini_get("post_max_size");

This is the way you get the values of a PHP directive. It is a very handy function.
It can be used to:
* check if register globals is active on server or not: ini_get(“register_globals”)
* check what is the max upload and post size at upload: ini_get(“post_max_size”), ini_get(“upload_max_filesize”)
* check what is the max execution time for a script: ini_get(“max_execution_time”)
* get the include path: ini_get(“include_path”)
and plenty more. I just listed a few of the most common use of this function.

To change a directive use ini_set(). ini_set() is not enabled on every host, for security reasons, or it’s usage is limited to a few directives, so pay attention!!!

ini_get() documentation:
http://php.net/manual/en/function.ini-get.php

ini_set() documentation:
http://www.php.net/manual/en/function.ini-set.php