How do you use multiple rails versions with rbenv?

not sure if you got an answer to this, but I thought I'd offer what I did and it seemed to work.

So once you get rbenv installed, and you use it to install a specific ruby version, you can install multiple versions of rails to for that ruby.

STEP 1. Install whatever version(s) of rails you want per ruby version

% RBENV_VERSION=1.9.2-p290 rbenv exec gem install rails --version 3.0.11

By using the "RBENV_VERSION=1.9.2-p290" prefix in your command line, you're specifying which ruby rbenv should be concerned with.

Then following that with the "rbenv exec" command, you can install rails. Just use the version flag as in the example to specify which version you want. Not sure if you can install multiple versions in one shot, but I just run this command as many times as needed to install each version I want.

Note: This will all be managed within your rbenv directory, so it's perfectly safe and contained.

STEP 2. Build a new rails project by specifying the rails version you want.

% RBENV_VERSION=1.9.2-p290 rbenv exec rails _3.0.11_ new my_project

STEP 3. Don't forget to go into that project and set the local rbenv ruby version.

% cd my_project% rbenv local 1.9.2-p290

Now if you want to delete this project, just delete it as normal.

If you want to delete / manage a rails version from rbenv gems, you can use regular gem commands, just prefix your command line with:

% RBENV_VERSION=1.9.2-p290 rbenv exec gem {some command}

And of course, you can delete a complete ruby version and all its shims, etc that are managed within rbenv pretty easily. I like how self contained everything is.

Hope this helps.

For reference, this is a pretty good walk through of at least some of this stuff:

http://ascarter.net/2011/09/25/modern-ruby-development.html

There is a rbenv plugin called rbenv-gemset which should behave similar to the rvm gemset-command but since rbenv was never intended to work this way, I haven't tried it.

I usually manage Rails versions with Bundler as Nathan suggested in the comments of one of the other answers. I create a Gemfile with my desired Rails version, run bundle install, create the Rails application, let it replace the Gemfile and let Bundler take over:

mkdir my-rails-appcd my-rails-appecho "source 'https://rubygems.org'" > Gemfileecho "gem 'rails', '3.2.17'" >> Gemfilebundle installbundle exec rails new . --force --skip-bundlebundle update

If you want more detail, I wrote an article on my blog about it.

Hope it helps!