Whenever I need to install different versions of Ruby and Rails, I use
rbenv to manage my Ruby packages and this post will show you how to use it too.
To install multiple versions of Ruby on your computer, you'll need a Ruby package manager. The two most popular products are Ruby Version Manager (RVM) and Rbenv. This article assumes you have
rbenv installed. If you have not installed
rbenv yet, read this tutorial.
Step 1 - Install Ruby
You first need to install the right version of Ruby for your app. If you are working with an existing rails project, the easiest thing to do is look at the
For example, here is the
Gemfile of a sample Rails 4 app for Heroku. It requires Rails
4.2.3 and Ruby
rbenv install 2.2.1
After rbenv installs ruby, run this.
You can double-check your work by asking rbenv to list which versions of Ruby you have installed.
Step 2 - Install Rails
Now let's tell rbenv which version of Ruby to use when installing rails.
RBENV_VERSION=2.2.1 rbenv exec gem install rails --version 4.2.1 --no-ri --no-rdoc
We are skipping the documentation
--no-rdoc so that we can speed up the installation process.
Step 3 - Create a Rails app
Create a new version of rails using a specific version of Ruby.
RBENV_VERSION=2.2.1 rbenv exec rails _4.2.1_ new [my_rails_4_app]
Step 4 - Set your local Ruby version
Change directory into your project.
Set the local Ruby version.
rbenv local 2.2.1
Local enables you to keep your global version of Ruby yet use
4.2.1 on this local app.
Step 5 - Start Rails web sever