What tools are available to auto-format Ruby/Rails Code

Question

I'm currently using GEdit with several plugins to do Ruby on Rails development. One thing I would like to have is a way to automatically format my source files (.rb, .*.erb, etc.) Ideally it would be something that I could call from the command line and/or GEdit.

Command line tool would be nice, because I can set up a Git hook to auto-format on commit.

What are my options? What are the pros and cons of each?

Answer 1

What about rubocop ?

rubocop -a will automatically fix your code syntax

Answer 2

It's not new but it works: http://www.arachnoid.com/ruby/rubyBeautifier.html