It is impossible not to learn ruby these days. It is used everywhere: ruby powers octopress, chef and many other popular software.

Here is some basic rvm command:

$ rvm list

rvm rubies

   ruby-1.9.3-p484 [ x86_64 ]
   ruby-1.9.3-p551 [ x86_64 ]
=* ruby-2.2.0 [ x86_64 ]

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


$ rvm use 2.2.0
Using /Users/antkong/.rvm/gems/ruby-2.2.0

$ bundle install
bash: bundle: command not found

$ gem install bundle
Fetching: bundler-1.7.12.gem (100%)
Successfully installed bundler-1.7.12
Fetching: bundle-0.0.1.gem (100%)
Successfully installed bundle-0.0.1
Parsing documentation for bundler-1.7.12
Installing ri documentation for bundler-1.7.12
Parsing documentation for bundle-0.0.1
Installing ri documentation for bundle-0.0.1
Done installing documentation for bundler, bundle after 1 seconds
2 gems installed