If you are using bundler:
$ bundle exec exceptional install YOUR-API-KEY
If you are not using bundler:
$ exceptional install YOUR-API-KEY
You will find the API_KEY in the apps settings screen within Exceptional.
$ exceptional test
You will see a test exception in your exceptional app screen
By default Exceptional will not collect errors and exceptions for the development(default) or test rails environments (as specified by RAILS_ENV). If you want exceptional collecting errors for those environments then you must enable that environment by adding the following lines to the config/exceptional.yml file.
e.g for the development environment
development: enabled: true