How to include the Yii class from anywhere inside the project directory?

I have this in the root directory projectAStar

<?php

/* Do not version control this file */

Yii::import('site.frontend.commands.*');

$command = new MyCommand("UpdateDB");

$command->run(null);

and I am getting the following error:

PHP Fatal error:  Class 'Yii' not found in /vagrant/bogus.php on line 3

PHP Stack trace:

PHP   1. {main}() /vagrant/bogus.php:0

[color="#006400"]/* Moved from "2.0" to "1.1" */[/color]