Using multiple versions of Ruby on the same host

I've recently come across a tool called RVM or Ruby Version Manager. It enables you to run different versions of Ruby on the same host.

RVM uses git so my first step was to install git with the Homebrew package manager. Homebrew is an increasingly popular alternative to MacPorts and Fink.

Note that you'll need to install Xcode first.

/usr/bin/ruby -e "$(curl -fsSL https://raw.github.com/gist/323731)"
brew install git

Then I just followed the instructions available here.

bash < <( curl http://rvm.beginrescueend.com/releases/rvm-install-head )
source ~/.rvm/scripts/rvm
rvm install jruby,1.9.2-head

Here is what the output looks like:

info: Downloading jruby-bin-1.5.1, this may take a while depending on your connection...
info: Extracting jruby-bin-1.5.1 ...
info: Building Nailgun
info: Installing JRuby to /Users/rpark/.rvm/rubies/jruby-1.5.1
info: Importing initial gems...
info: Installing rake
info: Installing Ruby from source to: /Users/rpark/.rvm/rubies/ruby-1.9.2-head
info: Downloading source from http://svn.ruby-lang.org/repos/ruby/branches/ruby_1_9_2.
info: Copying from repo to src path...
info: Running autoconf
info: Configuring ruby-1.9.2-head, this may take a while depending on your cpu(s)...
info: Compiling ruby-1.9.2-head, this may take a while depending on your cpu(s)...
info: Installing ruby-1.9.2-head
info: Installation of ruby-1.9.2-head is complete.
info: Updating rubygems for /Users/rpark/.rvm/gems/ruby-1.9.2-head@global
info: Updating rubygems for /Users/rpark/.rvm/gems/ruby-1.9.2-head
info: adjusting shebangs for ruby-1.9.2-head (gem irb erb ri rdoc testrb rake).
info: Importing initial gems...

The install is done. When you want to switch between different versions of ruby, just use the "rvm use" command:

rvm use 1.9.2-head
11:10:23[~:15]$ which ruby
/Users/rpark/.rvm/rubies/ruby-1.9.2-head/bin/ruby
11:11:06[~:16]$ which gem
/Users/rpark/.rvm/rubies/ruby-1.9.2-head/bin/gem
rvm use jruby
11:10:01[~:11]$ which ruby
/Users/rpark/.rvm/rubies/jruby-1.5.1/bin/ruby
11:10:06[~:12]$ which gem
/Users/rpark/.rvm/rubies/jruby-1.5.1/bin/gem

Then add this to the end of ~/.profile:

[[ -s "$HOME/.rvm/scripts/rvm" ]] && . "$HOME/.rvm/scripts/rvm"

RVM allows you to use different gemsets with each ruby version. One use case is working with Rails 2.3.3 and Rails 3.0. I didn't need this feature but it's nice to know it's there.

One final step is TextMate integration. This is described here.

rvm wrapper 1.9.2-head

Then run this script:

#!/usr/bin/env bash

mkdir -p /Library/Application\ Support/TextMate/

sudo chown -R $(whoami) /Library/Application\ Support/TextMate

cd /Library/Application\ Support/TextMate/

if [[ -d Bundles/.svn ]] ; then
  cd Bundles && svn up
else
  if [[ -d Bundles ]] ; then
    mv Bundles Bundles.old
  fi
  svn co http://svn.textmate.org/trunk/Bundles
fi

exit 0

Open up Shell Variables in TextMate's Preferences -> Advanced

Set TM_RUBY to /Users/rpark/.rvm/bin/textmate_ruby

Final step:

cd /Applications/TextMate.app/Contents/SharedSupport/Support/lib/ ; mv Builder.rb Builder.rb.backup