kain-osx:careme kain$ script/generate controller api/documents index show
      create  app/controllers/api
      create  app/helpers/api
      create  app/views/api/documents
      create  test/functional/api
      create  app/controllers/api/documents_controller.rb
      create  test/functional/api/documents_controller_test.rb
      create  app/helpers/api/documents_helper.rb
      create  app/views/api/documents/index.html.erb
      create  app/views/api/documents/show.html.erb
kain-osx:careme kain$ script/generate controller api/diagnoses index show
  The name 'api' is either already used in your application or reserved by Ruby on Rails.
  Please choose an alternative and run this generator again.

  Suggestions:  

Apus
genus Apus