1. Computing

Ruby Version Manager (RVM)

Ruby Version Manager (RVM) is a tool that allows you to install multiple versions of Ruby. It allows you to have multiple versions of the same interpreter, as well as multiple interpreters such as jRuby, MacRuby, Ruby Enterprise Edition, etc. And, for many, RVM has become the preferred way to install and keep a single version of Ruby up to date.

What is RVM?
RVM is the Ruby Version Manager. It allows you to install and manage several different versions and implementations of Ruby on one computer, including the ability to manage different sets of RubyGems one each.

What's your favorite way to use RVM?
RVM has a lot of uses. Ultimately, it will be useful to all Rubyists, but what is your favorite use of RVM?

Installing Rubies
Finally, you've installed RVM and gotten a list of Rubies, it's time to install a Ruby version. Once everything is set up, this is really quite easy. The only command you need to know is rvm install.

Listing Known Rubies
In RVM-speak, a "Ruby" is a version of Ruby either installed or it knows has to install. Before you can instally and Rubies, you first have to know which Rubies RVM knows about.

Using Rubies
Now that you've installed a Ruby or two, it's time to start using them. First, list which Rubies you have installed using the rvm list command. This will list the Rubies installed, if you have many installed you should run it often to remind yourself of their shortened names.

Step by Step Instructions
Installing the Ruby Version Manager (RVM) on Linux

Upgrading RVM
How to upgrade RVM (Ruby Version Manager)

Using RVM Gemsets
One of the most powerful, useful and often overlooked features of RVM is the gemset. A gemset is a separate gem directory, so the gems in one gemset don't conflict with the gems in another gemset.

Upgrading to 1.9.2 Using RVM
If you already have a Ruby like 1.9.2-rc2 installed with a number of gems and want to upgrade to 1.9.2-p0, the following steps will get you there. As expected,RVM makes this quite easy.

Upgrading to RVM Head
RVM is a moving target. It's still under regular development and in order to get the most current versions of Ruby, you'll need to upgrade to the head version of RVM. This is the version checked out directly from its GitHub repository.

Installing Ruby on Snow Leopard with RVM
So, you've gotten your shiny new Mac and you want to get right into Ruby programming, where how do you install it? The first thing you should know is that it's already installed. OS X 10.6 "Snow Leopard" comes with both Ruby 1.8.7 and Ruby on Rails 2.3.5 installed. But there are a lot of reasons why you'd want to install your own with RVM,...

RVM and 'sudo'
RVM is great. However, there may be times where you must run Ruby scripts with RVM as root (or another user) via sudo.

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