rbenv

rbenv does… - Let you change the global Ruby version on a per-user basis. - Provide support for per-project Ruby versions. - Allow you to override the Ruby version with an environment variable. In contrast with rvm, rbenv does not… - Need to be loaded into your shell. Instead, rbenv's shim approach works by adding a directory to your $PATH. - Override shell commands like cd. That's dangerous and error-prone. - Have a configuration file. There's nothing to configure except which version of Ruby you want to use. - Install Ruby. You can build and install Ruby yourself, or use ruby-build to automate the process. - Manage gemsets. Bundler is a better way to manage application dependencies. If you have projects that are not yet using Bundler you can install the rbenv-gemset plugin. - Require changes to Ruby libraries for compatibility. The simplicity of rbenv means as long as it's in your $PATH, nothing else needs to know about it. - Prompt you with warnings when you switch to a project. Instead of executing arbitrary code, rbenv reads just the version name from each project. There's nothing to "trust."