deploy.rb

set :rails_env, ( ENV['RAILS_ENV'] = 'staging' )
set :ssh_name, "stage.#{application}"

desc "Use with deploy to push live"
task :live do
  set :rails_env, ( ENV['RAILS_ENV'] = 'production' )
  set :ssh_name, "live.#{application}"
end

before 'deploy:setup', :set_server

task :set_server do
  server ssh_name, :app, :web, :db, :primary => true
end

# then make sure to add `RAILS_ENV=#{rails_env}` in front of any command line things you're running on the server