pi@raspberrypi:~ $ rvm -v
rvm 1.26.11 (latest) by Wayne E. Seguin <wayneeseguin@gmail.com>, Michal Papis <mpapis@gmail.com> [https://rvm.io/]

pi@raspberrypi:~ $ rvm install ruby
Searching for binary rubies, this might take some time.
No binary rubies available for: debian/8/armhf/ruby-2.2.1.
Continuing with compilation. Please read 'rvm help mount' to get more information on binary rubies.
Not enough space (297MB) to install ruby (440MB).