so i have a plesk server and want to share a single function.php

I've put this in the httpdocs/includes directory (plesk) but want to include from a file in httpsdocs how do i achieve this... I've tried

PHP Code:

include('../httpdocs/includes/function.php'); 


also

PHP Code:

include('/var/www/vhosts/mydomain/httpdocs/includes/function.php'); 


the latter works on files in the httpdocs folder but not the httpsdocs...

any help?

No much luck here.
Https probably is shared between every users of the hosting facility, and have a different web path.
This means that you must address explicitely the path to your files.
Or have a check done first, and adapt a variable with the correct path prefix, like:
(in pseudo code)

PHP Code:

if protocol=='https' then
 $path="/var/www/vhosts/mydomain/httpdocs";
else
  $path=$_SERVER['DOCUMENT_ROOT']; 


and use this $path variable when you do includes.