I created a new staging environment for my Rails application called
"staging". I would like to use the production database while in the
staging mode. I'm pretty sure I need to modify environments/staging.rb
(which I cloned from environments/production.rb), but I don't know
which variable to set to the production database and how.
If you've already set up the configured environment can't just add a
staging section to your database.yml that points to the production db?
Have you checked out #72 Adding an Environment - RailsCasts