rbenv
Groom your app’s Ruby environment
...Specify your app's Ruby version once, in a single file. Keep all your teammates on the same page. No headaches running apps on different versions of Ruby. Just Works™ from the command line and with app servers like Pow. Override the Ruby version anytime: just set an environment variable. Rock-solid in production. Your application's executables are its interface with ops. With rbenv and Bundler binstubs you'll never again need to cd in a cron job or Chef recipe to ensure you've selected the right runtime. The Ruby version dependency lives in one place—your app—so upgrades and rollbacks are atomic, even when you switch versions. ...