Get available versions from command line

Hi there!

I want to deploy updates only for the last X versions of my application. (The creation of the updates is part of our automated deployment process.)

So I have to know which previous versions of the application are available. (Till now we are using a horrible solution containing creating a file list and parsing the file names from the updates-directory). Which is the correct way to determine the available versions from a wyp-file?

Best regards from Germany Sebastian