It's a very useful function
I've been using it a lot to do a lot of things. Like creating navigation and displaying links only on certain pages. Like it doesn't make sense on index.php to have the logo linking to index.php so:
PHP Code:
<?php
if (eregi("index.php",$_SERVER['PHP_SELF'])) {
echo "<img src=\"logo.jpg\" alt=\"logo\" />";
} else {
echo "<a href=\"index.php\"><img src=\"logo.jpg\" alt=\"logo\" border=\"0\" /></a>";
}
?>
Of course it can be used to keep people off of included pages