Create new file in path below

I am trying to make an installer script for my project but i need a little help.

how can i set a variable of the path below

so say i currently am in /var/www/auto/install/ but i want the installer file to create /var/www/auto/config.php

i dont want to hardcode the /var/www/ path so that any one else who installs my script does not have to alter it.

<?php

$fileToCreate = dirname( FILE ) . ‘/…/config.php’;
// or, better, for PHP 5.3+
$fileToCreate = DIR . ‘/…/config.php’;

?>

Brilliant Thank you very much!