<?php session_start();output_add_rewrite_var('var', 'value'); echo '<a href="file.php">link</a>';ob_flush();output_reset_rewrite_vars(); echo '<a href="file.php">link</a>';?>
The above example will output:
<a href="file.php?PHPSESSID=xxx&var=value">link</a> <a href="file.php">link</a>