One way is to render sitemap.xml using PHP
(.htaccess)
Code:
AddType application/x-httpd-php .xml
Then inside your XML file:
Code:
<?php
$lastmod = date('Y-m-d');
$header .= "<?xml version=\"1.0\" encoding=\"UTF-8\"?>";
$header .= "<urlset xmlns=\"http://www.google.com/schemas/sitemap/0.84\"
xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"
xsi:schemaLocation=\"http://www.google.com/schemas/sitemap/0.84
http://www.google.com/schemas/sitemap/0.84/sitemap.xsd\">";
echo $header;
?>
then include $lastmod in XML:
Code:
<url><loc>http://www.example.com</loc>
<lastmod><? echo $lastmod; ?></lastmod></url>
Problem with this approach is all your XML files in the root directory will not show correctly in many browsers.