From RVM to rbenv

• Introduction
• Installation
• Moar Rubies!
• Activating a Ruby

Introduction

Over the last day or so I’ve been slowly moving my ruby projects over to using rbenv instead of RVM. There’s nothing inherently wrong with RVM, but I do lots of interesting things with my shell that, when combined with my tmux setup, seems to always be giving me flak.

So at the recommendation of a friend, I sat down with rbenv for a couple of hours, and these are my notes from that experience.

Installation

Typically, I would not make a change so drastically, but I found the process of converting to be fairly painless and simple enough for me to go back to if need be without much fanfare. The process for me was to …

1. Remove any source references to RVM scripts in my .bashrc and .bash_profile files
2. Remove any path modifications that include the RVM bin dir
3. Use homebrew to install rbenv (alternatively, you could clone the repository¹ into ~/.rbenv
4. Add the following into my .bashrc

if which rbenv > /dev/null; then eval "$(rbenv init -)"; fi

Moar Rubies!

If all went well above, we should have a working rbenv installation. Now let’s take a look at the rubies currently available –

$ rbenv versions
* system (set by /Users/arusso/.rbenv/version)

I only have a single ruby version install initially, but with the help of the ruby-build² plugin (available via hombere), I get access to the rbenv install command where I can install new versions of ruby.

In this case, my system ruby is version 2.0.0-p481 (ruby -v). This is too new for all my work, since I do a good deal with Puppet on RHEL6 which ships with 1.8.7-p374. Let’s start by installing that version –

$ rbenv install 1.8.7-p374
Downloading ruby-1.8.7-p374.tar.gz...
-> http://dqw8nmjcqpjn7.cloudfront.net/876eeeaaeeab10cbf4767833547d66d86d6717ef48fd3d89e27db8926a65276c
Installing ruby-1.8.7-p374...
Installed ruby-1.8.7-p374 to /Users/arusso/.rbenv/versions/1.8.7-p374

Downloading rubygems-1.6.2.tgz...
-> http://dqw8nmjcqpjn7.cloudfront.net/cb5261818b931b5ea2cb54bc1d583c47823543fcf9682f0d6298849091c1cea7
Installing rubygems-1.6.2...
Installed rubygems-1.6.2 to /Users/arusso/.rbenv/versions/1.8.7-p374

Now looking at the versions available to us, we see –

$ rbenv versions
* system (set by /Users/arusso/.rbenv/version)
  1.8.7-p374

Activating a Ruby

I typically activate rubies in two ways. First and foremost, when I’m switching between rubies for testing I used to use rvm use $version to get the ruby I want. With rbenv, this becomes rbenv shell $version.

The second way I choose rubies is by setting my ruby version in the .ruby-version file in my project directory. Fortunately, this does not really change and I can mostly leave it alone³.

For more information on how rbenv chooses a ruby version, see the project’s README section⁴ on the subject