How to: Environment Management
* [chruby](https://github.com/postmodern/chruby) - Change your current Ruby. No shims, no crazy options or features, ~90 LOC.
* [fry](https://github.com/terlar/fry) - Simple ruby version manager for fish.
* [gem_home](https://github.com/postmodern/gem_home) - A tool for changing your $GEM_HOME.
* [rbenv](https://github.com/sstephenson/rbenv) - Use rbenv to pick a Ruby version for your application and guarantee that your development environment matches production.
* [ruby-build](https://github.com/sstephenson/ruby-build) - Compile and install Ruby.
* [ruby-install](https://github.com/postmodern/ruby-install) - Installs Ruby, JRuby, Rubinius, MagLev or MRuby.
* [RVM](https://rvm.io) - RVM is a command-line tool which allows you to easily install, manage, and work with multiple ruby environments from interpreters to sets of gems.
* [Tokaido](https://github.com/tokaido/tokaidoapp/releases) - Ruby, Rails, SQLite and Redis encapsulated in a single drag-and-drop OS X app, designed to make installing a working RoR environment easy for beginners.
* [Uru](https://bitbucket.org/jonforums/uru) - Uru is a lightweight, multi-platform command line tool that helps you use the multiple rubies on your 32/64-bit Linux, OS X, or Windows systems.