Award-Winning Fjords Thomas Reynolds

Using RVM to Manage Multiple Ruby Interpreters

I've been hearing a bit of buzz about the Ruby Version Manager project on Twitter and from other Rubyists I know. Basically, the project provides a command-line tool which can download and compile a large number of Ruby implementations and swap between the active implementation on a per-terminal basis.

This is especially useful for me as I have Ruby tools, like Middleman, which I need to maintain on multiple VMs. In the past, you'd have to install each VM to it's own namespace and be very careful when running them to make sure you were in the right VM. For example:

ruby: The default OSX ruby 1.8.7
ruby19: My custom-compiled ruby 1.9.1
jruby: My custom-compiled jRuby
macruby: My custom-compiled MacRuby

RVM makes managing these interpreters a snap. So here's how you get started.

Install the gem

gem install rvm

Run the installer


Follow instructions and append the output of the install to your terminal profile

In ~/.profile
Add to the bottom:

if [[ -s /Users/tdreyno/.rvm/scripts/rvm ]] ; then source /Users/tdreyno/.rvm/scripts/rvm ; fi

Then, save and close ~/.profile and run:

source ~/.profile

Now, you are ready to go.


First, lets see which Ruby VMs the tool detected.

rvm list

My output includes the built-in OSX VM.

System Ruby

   system [ x86_64 i386 ppc ]

Now, I want to install some more Rubies.

rvm install 1.9.1,rbx,jruby,macruby

A couple of minutes later, you'll have 5 different Ruby VMs installed. RBX is Rubinius and the others should be self-explanatory.

Swapping VMs

To change between the active VM, simply run:

rvm use 1.9.1

And now ruby -v returns "ruby 1.9.1p378 (2010-01-10 revision 26273) [i386-darwin10.2.0]"

In my case, I can now run my Cucumber tests against my library and verify that it's working with Ruby 1.9.1.

To return to your original VM, run:

rvm use system

Be aware that each VM probably has it's own gems. So you'll need to be aware of that and try to keep each VM's gems in sync.