daryl.mu

1. Enable the universe repository
sudo vi /etc/apt/sources.list
Find and uncomment the following lines
deb http://us.archive.ubuntu.com/ubuntu dapper universe main restricted universe
deb http://security.ubuntu.com/ubuntu dapper-security universe

2. Install ruby
sudo apt-get install ruby ri rdoc

3. Install rubygems
sudo apt-get install rubygems

4. Install Rails
sudo gem install rails
NOTE: If you get, as I did, an error at this point:

uninitialized constant Gem::GemRunner

then the fix is:
sudo vi /usr/bin/gem
After the line require ‘rubygems’ add the line:
require 'rubygems/gem_runner'

5. Test installation
cd
rails testapp
cd testapp
./server start
Open a browser to http://localhost:3000 and you should see the rails welcome page.

You can remove the testapp with:
cd
rm -fr testapp