链接到include_path中的文件

Question

I am trying to understand how to have a require_once directive point to a php file located in a folder belonging to a path specified in a php.ini include_path. This folder is located before public_html. Here is, roughly, the web structure as it stands:

   .cpanel
   .cpanel-datastore
   access-logs
   etc
   include_path
        /folder1
             //session.php
             //db_connection.php
             //functions.php
   public_html
        /folder
             //File_with_require_once.php
   ssl

Now, of course, the php.ini file is located in public_html

And the question again is, in File_with_require_once.php, when I make the call for :

<?php require_once("????????/session.php"); ?>
<?php require_once("????????/db_connection.php"); ?>
<?php require_once("????????/functions.php"); ?>

What do I write instead of the question marks?

I hope I am being clear... Can somehow help? Thank you.