Standard File Naming Conventions in Ruby

With just Ruby (i.e. not Rails), naming is only a convention. In Rails the convention of using underscores is necessary (almost).

I think convention #2 lowercase_and_underscore.rb is more common and looks pretty good, though an article Here says lowercasenounderscore.rb is the Ruby convention.

Pick either which ever convention is more common or which ever one you like more. The most important thing is to be consistent within a project.