RailsOnUbuntu

This is a new guide for installing Rails on Ubuntu. You can find the old instructions under RailsOnUbuntuDebianTestingAndUnstable.

A French guide for Edgy can be found here (an Edgy guide in English is linked below) : Ubuntu Edgy Eft – Installer RubyOnRails & Eclipse – RadRails
The quickest way

(Not recommended, see the Community Ubuntu Documentation for more info. These instructions need to be updated.)

Simply copy and paste the following into a terminal:

$ sudo apt-get install ruby rubygems irb ri rdoc ruby1.8-dev build-essential
$ sudo gem install rails --include-dependencies
$ export PATH=$PATH:/var/lib/gems/1.8/bin


A brief word about Rubygems

Since Rubygems has the potential to disrupt package management it has only recently been packaged for Debian and, by extension, Ubuntu.

For more information please read Debian’s position on Rubygems
Versions and Availability

Rails has been packaged for Ubuntu since release 5.10 (Breezy Badger) – the following table lists the versions of Rails and Ruby available in each release of Ubuntu:
5.04 (Hoary) 5.10(Breezy) 6.06 LTS (Dapper) 6.10 (Edgy) 7.04 (Fiesty)
rails 0.13.11 0.13.1 1.1.2 1.1.6 1.2.1
ruby 1.8.12 1.8.2 1.8.23 1.8.23 1.8.23
ruby1.8 1.8.12 1.8.2 1.8.4 1.8.4 1.8.5
rubygems n/a n/a n/a n/a 0.9.0

1. Only available through backports
2. 1.8.2 was available through backports
3. This is version reported by http://packages.ubuntu.com but as the package depends on ruby1.8 you actually get the version below

Since Rails is available as a package, Rubygems is no longer required to install it. However as the current version of Rails in Feisty is a couple of versions behind, and Rubygems provides far more than just Rails, two ways of installing Rails are demonstrated.

For the time being all instructions are tested on Ubuntu 7.04 (Feisty Fawn), although they may work for previous releases.
Out of Scope

This guide currently only covers installing Rails on Ubuntu. Installation of database servers, web servers, gems (besides Rails and it’s dependencies) are not covered.
The ‘proper’ way

This method of installing Rails uses only the official packages. Simply run:

$ sudo apt-get install rails

This will install the stable (from the distributions point-of-view) versions (see table above for specifics) of Rails and Ruby. you can confirm the version with:

$ ruby -v

The only package not installed using this method is irb which simply provides a softlink to irb1.8 in /usr/bin. You could create this link yourself, or just install the irb package via apt-get.
The recommended way

(Not really recommended, see the Community Ubuntu Documentation for more info. These instructions need to be updated.)

This method installs Ruby and Rubygems via packages, and Rails via Rubygems. This is much more flexible arrangement than the ‘proper’ method above. It does however mean that you can confuse apt by installing a Ruby library through gem instead of apt.
Ruby

Install Ruby and RubyGems with the following:

$ sudo apt-get install ruby rubygems irb ri rdoc ruby1.8-dev build-essential

Note: ruby1.8-dev and build-essential are not required to install either Rubygems, Rails or it’s dependencies, but they do make life much easier if you’re going to be using other gems. So we’ll just get them out of the way now.
Rails

Now you can install Rails via Rubygems:

$ sudo gem install rails --include-dependencies

Now add /var/lib/gems/1.8/bin/ to your path, and you’re done!
Database server and driver

Now you just need a database server (or SQLite) as well as a Ruby-driver for it. For the vast majority MySQL should do:

$ sudo apt-get install libmysql-ruby mysql-server


(You can leave out the “mysql-server” if you’ve already got the MySQL server installed and only need the driver.)

If you’re not satisfied with MySQL, and you can’t figure out which apt packages to install for your preferred database, then see DatabaseDrivers for details on how to install the correct drivers for your environment via gem (not available if you installed Rails “The ‘proper’ way”).

TO-DO: Provide details on installing native database drivers other than MySQL via apt.
SSL Support

If you’re looking to use net/https then you’ll need to install the lib for openssl:

$ sudo apt-get install libopenssl-ruby

ImageMagick Support

If you need RMagick support for your web app, you are going to need to install ImageMagick and RMagick.

sudo apt-get install imagemagick
dpkg -l | grep magick

This will install the most current imagemagick and then list the ‘magick’ packages installed. Look for what version of libmagick got installed and make sure you specify THAT version number when you install libmagick-dev.

sudo apt-get install libmagick9-dev
sudo gem install rmagick

After a lengthy build process, you’re ready to edit images in ruby!