Reek is a code smell detection for Ruby.It can examine Ruby classes, modules and methods and reports any Code Smells it finds. 

It's similar to pep8. So I imitate the file named pep8.py when I writing this document.

This document tries to use the reek as a plugin to detect the file ending with ".rb".

gem install reek

reek [options] [dir_or_source_file]*