Last time we complete the Ruby 1.9.2 installation on Ubuntu Lucid.
Ruby – Installation on Ubuntu Lucid

Similar to the above post, run the following commands in your own account but not root account. Let’s proceed to the Rails 3.0 installation now.

1. Install Rails 3.0

• gem install i18n tzinfo builder memcache-client rack rack-test rack-mount erubis mail text-format thor bundler
• gem install rails

 

2. Check the version of the installed Rails.

• rails -v

 

3. Install SQLite

• sudo apt-get install sqlite3 libsqlite3-dev
• gem install sqlite3-ruby

 

Done =)

Reference: Install Ruby 1.9.2 and Rails 3 on Ubuntu 10.04 for Ruby on Rails Workshop