BackTrack 5 comes with 2 versions of ruby shipped - 1.9.2 and 1.8.7. The default is 1.9.2.
Depending on your needs, the default version of ruby can be switched using the "update-alternatives" command.
Remember that few tools in BackTrack depend on a certain ruby version in order to run, such as whatweb, cewl, warvox, etc. These tools will require that you switch your ruby version before use.Code:update-alternatives --config ruby