If you do

  apt-get install ruby-rvm

On any Ubuntu distro, you are going to have a really bad time.

Proper directions are on Stack overflow, where the RVM repository owner mentions that he wishes the Ubuntu ruby-rvm package would be dropped.

SO link http://stackoverflow.com/questions/9056008/installed-ruby-1-9-3-with-rvm-but-command-line-doesnt-show-ruby-v/9056395#9056395