Getting started with RVM using RiversideRuby website as an example.

2011-03-03 · 3 min read

The major benefit of using rvm is for organization. When you start to have multiple projects that span different versions of Ruby, Rails, gems, etc.; you’ll need a way to separate your gems in a clear way. You also get the benefit of organizing the gems you use for your projects, say you are working with Rails in one project and Sinatra in another.

You can find setup guides here for OSX and here for Ubuntu.

First lets install the latest Ruby [Ruby 1.9.2-p180] for rvm.

rvm list
# will show you all Rubies installed in your current system, we have nothing because nothing has been installed
 
rvm list known
# will show you all Rubies that are known to rvm
 
rvm install ruby-1.9.2-p180
# this will install Ruby 1.9.2 p180
 
rvm list
# see we installed Ruby 1.9.2 correctly

Now the fun part. Lets see what Ruby we are using.

which ruby && ruby -v
# returns your system ruby
# /usr/local/bin/ruby
# ruby 1.9.2p180 (....) [x86_64-darwin10.6.0]

Lets use rvm Rubies.

rvm use ruby-1.9.2
# returns
# Using /User/[username]/.rvm/gems/ruby-1.9.2-p180
 
which ruby && ruby -v
# returns rvm’s ruby
# /Users/[username]/.rvm/rubies/ruby-1.9.2-p180/bin/ruby
# ruby 1.9.2p180 (....) [x86_64-darwin10.6.0]

Lets say we need to work on a legacy Ruby 1.8.7 app.

rvm install ruby-1.8.7 
 
rvm list
# returns a list of rubies rvm has installed

Now I don’t like typing periods, dashes, and such so I give my Rubies aliases.

rvm alias create r187 ruby-1.8.7
rvm alias create r192 ruby-1.9.2
 
rvm alias list
# returns your list of aliases
 
# now some fun stuff lets switch rubies
 
rvm use r187
 
which ruby && ruby -v
# returns
# .../.rvm/rubies/ruby-1.8.7-p344/bin/ruby
# ruby 1.8.7 ...
 
rvm use r192
 
which ruby && ruby -v
# returns
# .../.rvm/rubies/ruby-1.9.2-p180/bin/ruby
# ruby 1.9.2 ...
 
# Cool! Right. This will be better when I show you gemsets.

If you ever want to know what ruby you are using with rvm.

rvm current

If you want to use the system ruby.

rvm use system
# returns
# Now using system ruby.
 
# to see if that’s true
 
which ruby && ruby -v
# sweet!

Another useful rvm command for you to see more information is.

rvm info
# this gives in detail the information on the ruby you are using. useful when we use gemsets

Now RiversideRuby. Lets use Ruby1.9.2. Create a gemset for RiversideRuby, a fake new Rails 3.0.3 app, and a fake old legacy Rails 2.2.2 app.

rvm use r192
 
rvm gemset create riversideruby 
rvm gemset create rails303project
rvm gemset create rails222project

RiversideRuby (RR) is a Sinatra app, lets go get the required gems.

rvm r192@riversideruby
gem install sinatra --no-ri --no-rdoc
gem install haml --no-ri --no-rdoc
 
rvm info

For our fake Rails 3.0.3 Project

rvm r192@rails303project
gem install rails -v 3.0.3 --no-ri --no-rdoc
 
gem list

For our fake legacy Rails 2.2.2 Project

rvm r192@rails222project
gem install rails -v 2.2.2 --no-ri --no-rdoc
 
gem list

See what we got.

rvm r192@riversideruby && rails -v
# oh it blew up, why because rails is not installed and it’s not suppose to be
 
rvm r192@rails303project && rails -v
# returns
# Rails 3.0.3
 
rvm r192@rails222project && rails -v
# returns
# Rails 2.2.2

Now we have multiple versions of Ruby installed, multiple versions of Rails, and multiple projects with under 1.9.2 with different gems all organized.

Now what if there was a way to make this all seamless and you didn’t have to switch back and forth. rvm r192@riversideruby, rvm r192@rails303project, etc.

Lets make these projects.

Make a Code Directory. Just a personal preference I place all my work under ~/Code

mkdir ~/Code && cd ~/Code

These are just place holders rather than running rails rails222project or rails rails303project

mkdir rails222project rails303project

Git the RR site.

git clone https://[username]@github.com/[username]/riversideruby.git

If I ls in my Code directory I should get.

ls
# returns
# rails222project rails303project riversideruby

Auto rvm with .rvmrc

echo “rvm r192@rails222project” > ~/Code/rails222project/.rvmrc
echo “rvm r192@rails303project” > ~/Code/rails303project/.rvmrc
echo “rvm r192@riversideruby” > ~/Code/riversideruby/.rvmrc

Now I should be able to do this.

cd ~/Code/rails222project && ruby -v ; rails -v
cd ~/Code/rails303project && ruby -v ; rails -v
cd ~/Code/riversideruby && ruby -v
 
# note allow the trusting of the .rvmrc files you just created

Now everytime you cd into a project path you are using the correct version of ruby and gemsets.
Read up on all things RVM here.

Now back to RiversideRuby.

cd ~/Code/riversideruby
 
ruby app.rb

Fin.