列出ruby版本

console:~$ rvm list

rvm rubies

ruby-2.0.0-p481 [ i686 ]

# => - current
# =* - current && default
#  * - default

尝试使用特定版本的ruby

console:~$ rvm use 2.0.0

RVM is not a function, selecting rubies with 'rvm use ...' will not work.

You need to change your terminal emulator preferences to allow login shell.
Sometimes it is required to use `/bin/bash --login` as the command.
Please visit https://rvm.io/integration/gnome-terminal/ for a example.