Switch from RVM to RBENV

rvm2rbenv.txt

## Prepare ###################################################################

# Remove RVM
rvm implode

# Ensure your homebrew is working properly and up to date
brew doctor
brew update

## Install ###################################################################
brew install rbenv
brew install ruby-build

## Config ####################################################################

# Instantiate rbenv with your shell (choose preferred file - .profile, .bash_profile, .zshrc, etc)
printf 'eval "$(rbenv init -)"' >> ~/.profile

# Remove the RVM stuff from your .profile - It probably looks like...
[[ -s "$HOME/.rvm/scripts/rvm" ]] && . "$HOME/.rvm/scripts/rvm" # Load RVM function

# Reload your profile
. ~/.profile

# Add autocompletion to IRB
touch ~/.irbrc
printf "require 'irb/completion'" >> ~/.irbrc

## Usage #####################################################################
rbenv

# Choose a ruby flavor version to install
rbenv install 1.9.3-p0
rbenv install 1.9.2-p290

# Rehash rbenv shims (run this after installing binaries)
rbenv rehash

# Set the global Ruby version and install bundler globally
rbenv global 1.9.3-p0

#SET GLOBAL RUBY BEFORE INSTALLING GEMS

gem install bundler --pre
gem install OTHER_GLOBAL_GEMS # eg) Rails, Heroku, etc - NOTE: You need to do this for each ruby version.

rbenv rehash