gem-nuke

Plugin for gem that will allow you to uninstall all gems except for those that are 'vaulted'.

$ gem install gem-nuke

$ gem nuke

This will uninstall all gems including gem-nuke itself.

$ gem nuke --vault bundler,gem-nuke,...

This will uninstall all gems except for bundler, gem-nuke and others specified as comma separated gem names.

If you don't want to supply --vault option every time you run gem nuke or just to avoid accidental nuke of important gems, you can set default value for this option by editing your ~/.gemrc and adding

nuke: --vault gem-nuke,bundler,and_or_other_gems