http://hollandonrails.nl/articles/474-Editing-gems There are those days when you would like to edit the gem that you are using. Usually, the best way is just to checkout the gem at "github":http://github.com or "gemcutter":http://gemcutter.org, but if you want to edit a specific version, or just a quicklook this can become somewhat time consuming. Instead of searching the web for the source, you could always just look at your gem locally. Mine are installed at: <code> /Library/Ruby/Gems/1.8/gems/ </code> But, there is, off course, also a *gem* to edit gems! <code> gem install gemedit </code> And then you can just edit your executing a command like this: <code> gem edit gemname </code> Sinds a lot of developers use "textmate":http://macromates.com : <code> gem edit devise -e mate </code> Or you could just add *$GEMEDITOR* to your profile. If you have *$EDITOR* already set, it will pickup that, or fall back to "vi":http://en.wikipedia.org/wiki/Vi if no editor is specified.