include page with domain

I'm not entirely clear on what you're asking.

If you want domain1.com to include the file domain1.com/footer.php, but domain2.com to include the file domain2.com/footer.php using the same code, then could you use this:

include('/footer.php');

That uses an absolute path that looks for footer.php in the root directory. So if the current script is in the space for domain1.com, then PHP should ask for domain1.com/footer.php and so on. I think that would work even if the domains were on the same server. (So long as the domains didn't point to the same directory.)

<? include("DOMAIN WHERE YOU CAME FROM/footer.php"); ?>

instead of  this
<? include($_SERVER["DOCUMENT_ROOT"]."/galleries/main/header.php"); ?>
/home/etc/site/galleries/main/header.php

i want something like this
<? include($_SERVER["DOMAIN"]."/galleries/main/header.php"); ?>
http://domain.com/galleries/main/header.php

<? include($_SERVER["HTTP_HOST"]."/galleries/main/header.php"); ?>
only shows this
domain.com/galleries/main/header.php

I need the http://