RVM
Ruby enVironment Manager (RVM)
RVM is a command-line tool that allows you to easily install, manage, and work with multiple ruby environments from interpreters to sets of gems. RVM is the acronym of Ruby enVironment Manager. It manages Ruby application environments and enables switching between them. RVM lets you deploy each project with its own completely self-contained and dedicated environment, from the specific version of ruby, all the way down to the precise set of required gems to run your application. Having a precise set of gems also avoids the issue of version conflicts between projects, which can cause difficult-to-trace errors and hours of hair loss. With RVM, no other gems than those required are installed. This makes working with multiple complex applications, where each has a long list of gem dependencies, much more efficient. RVM lets you easily test gem upgrades, by switching to a new clean set of gems to test with, while leaving your original set intact.