How to nuke all Ruby Gems from the system and start over

What's the easiest way to start over with Ruby Gems? I have Ruby 1.8.7 (OSX, ports) installed and I have also installed rails and some other random stuff a while back. Now the gems system seems to be total开发者_运维问答ly dysfunctional and I can't upgrade rails. So is there a way to just nuke the gems so I can reinstall all this stuff with current versions?

Wipe your current gems from GEM PATH directory (you can check it via $ gem env). Then run $ which -a gem to nuke the bin files. After that - reinstall rubygems from the source and enjoy your new rubygems life.