How can I see the exact version of my osCommerce?

In order to check the version of your osCommerce, you should open the includes/application_top.php file located in your osCommerce installation folder.

Look for these two lines:

// define the project version
define(‘PROJECT_VERSION’, ‘osCommerce Online Merchant v2.2 RC2a‘);

The value after PROJECT_VERSION defines your current osCommerce version.