This is the fastest way to get Ruby and Rails installed on a Slice, mainly from info at http://wiki.rubyonrails.org/rails/pages/RailsOnUbuntu. by Matt

Make sure the universe repository in /etc/apt/sources.list is uncommented:

deb http://us.archive.ubuntu.com/ubuntu dapper universe
deb-src http://us.archive.ubuntu.com/ubuntu dapper universe

# apt-get update
# apt-get install ruby irb ri rdoc ruby1.8-dev build-essential

That will take a minute. Next up ruby gems:

# wget http://rubyforge.org/frs/download.php/11289/rubygems-0.9.0.tgz <-- OLD VERSION
# wget http://rubyforge.org/frs/download.php/17190/rubygems-0.9.2.tgz
# tar -zxvf rubygems-0.9.2.tgz
# cd rubygems-0.9.2
# ruby setup.rb
# gem update

Now rails (2-3 minutes):

# gem install rails --include-dependencies

That’s it! To start a Rails project:

$ rails my_app
$ cd my_app
$ script/server

Now don’t forget, you DO need to install database support, such as MySQL or SQLite3.

# apt-get install libsqlite3-0 libsqlite3-dev sqlite3 swig libsqlite3-ruby
# gem install sqlite3-ruby

# apt-get install mysql-server libmysql-ruby

You should be good to go using an SQLite database for your Rails app. See here for more info.