Ubuntu
RVM have dedicated Ubuntu package, so please follow instructions posted here: https://github.com/rvm/ubuntu_rvm

For other Unix systems ( including OSx )

Install RVM (development version):
\curl -sSL https://get.rvm.io | bash

Install RVM stable with ruby:

\curl -sSL https://get.rvm.io | bash -s stable --ruby

Additionally with rails (poor man’s railsinstaller):

\curl -sSL https://get.rvm.io | bash -s stable --rails