Instead of hard coding the name of a script use a superglobal reference.
<form action="<?php echo $_SERVER['PHP_SELF']; ?>" method="post">
<?php if (isset($_POST['submit'])) { $text = $_POST['text']; $output_form = false; if ( empty($text) { echo 'Text is empty'<br />; } else { $output_form = true; } if ($output_form) { ?> <form method="post" action="<?php echo $_SERVER['PHP_SELF']' ?>"> <label for="text">Text:</label><br /> <input id="text" name="text" type="text" size="10" /> <br /> <input type="submit" name="submit" value="Submit" /> </form> <?php } ?>