Billy-

$a = ( in_array('mod_rewrite', apache_get_modules()) || strpos(shell_exec('/usr/local/apache/bin/apachectl -l'), 'mod_rewrite') !== false );
echo 'Mod rewrite is ' . ($a ? 'enabled' : 'disabled');

Billy-

function in_array_r($needle, $haystack, $strict = false) {
    foreach ($haystack as $item) {
        if (($strict ? $item === $needle : $item == $needle) || (is_array($item) && in_array_r($needle, $item, $strict))) {
            return true;
        }
    }
    return false;
}