Create a rails app in a specific version

You have installed various versions of rails (ie 3.0, 2.3.8, 2.3.5 etc). You want to create a new rails application for a specific version, and if you run rails app_name, it will create an application in the latest version you have installed.

Use the following if you want to create a specific rails (ie 2.3.8) application:

rails _2.3.8_ app_name