Examples: Run `puts Rails.env` after loading the app: <%= executable %> 'puts Rails.env' Run the Ruby file located at `path/to/filename.rb` after loading the app: <%= executable %> path/to/filename.rb Run the Ruby script read from stdin after loading the app: <%= executable %> - <% unless Gem.win_platform? %> You can also use the runner command as a shebang line for your executables: #!/usr/bin/env <%= File.expand_path(executable) %> Product.all.each { |p| p.price *= 2 ; p.save! } <% end %>