Quick and dirty way is to add a random query to the URL.
I.e., if you're doing something like
include("./whatever.txt");
Then make it
code:
<?php
t = time();
include("./whatever.txt?abc=".t);
?>
Because t is different every time, the URL will always be treated as unique.
I think that PHP is correct, it's been ages since I've written any
:D
That said, are you sure it's not the browser cache client side?
EDITED: 17 Jul 2012 20:29 by PILOTDAN