gistfile1.php

	// If it hasn't been modified since the last time this attachement was retrieved, there's no need to display it again.
	if (!empty($_SERVER['HTTP_IF_MODIFIED_SINCE']))
	{
		list($modified_since) = explode(';', $_SERVER['HTTP_IF_MODIFIED_SINCE']);
		if (strtotime($modified_since) >= filemtime($filename))
		{
			ob_end_clean();

			// Answer the question - no, it hasn't been modified ;).
			header('HTTP/1.1 304 Not Modified');
			exit;
		}
	}