why don’t you do it like this:
in the pages:
<html>
<head></head>
<body>
<?php $page="one"; include('navigation.php'); ?>
</body>
</html>
in the navigation.php
<div id="nav">
<ul>
<li>
<a <?php echo ($page == 'one') ? "class="active"" : ""; ?>
href="https://stackoverflow.com/questions/2913415/index1.php">Tab1</a>/</li>
<li>
<a <?php echo ($page == 'two') ? "class="active"" : ""; ?>
href="index2.php">Tab2</a>/</li>
<li>
<a <?php echo ($page == 'three') ? "class="active"" : ""; ?>
href="index3.php">Tab3</a>/</li>
</ul>
</div>
You will actually be able to control where in the page you are putting the navigation and what parameters you are passing to it.
Later edit: fixed syntax error.