Here's the console output:
sergio@sergio-VirtualBox:~$ rvm list
ruby-1.9.3 [ i386 ]
sergio@sergio-VirtualBox:~$ rvm use 1.9.3
sergio@sergio-VirtualBox:~$ ruby -v
The program 'ruby' can be found in the following packages:
Try: sudo apt-get install <selected package>
You have broken version of RVM. Ubuntu does something to RVM that produces lots of errors, the only safe way of fixing for now is to:
sudo apt-get --purge remove ruby-rvm sudo rm -rf /usr/share/ruby-rvm /etc/rvmrc /etc/profile.d/rvm.sh
open new terminal and validate environment is clean from old RVM settings (should be no output):
env | grep rvm
if there was output, try to open new terminal, if it does not help then restart your computer.
\curl -L https://get.rvm.io | bash -s stable --ruby --autolibs=enable --auto-dotfiles
If you find you need some hand-holding, take a look at Installing Ruby on Ubuntu 12.04, which gives a bit more explanation.