"It's installed Gem but not as we know it"
– Bones, if he was a Ruby Developer –
Unfortunately, a careless keystroke can leave gems in lots of unusual places. About five minutes ago, that fate befell me as I ended up with gems under my home directory at ~/.gems. Not what I was expecting. To make matters worse when I tried to remove them I had no success - possibly there were PATH or GEM_PATH issues
Fortunately, Google was to the rescue before you could say ‘gem is no apt-get’, with the command…
gem uninstall ruby-debug-ide --install-dir $HOME/.gem/ruby/1.8
… where in this case ruby-debug-ide is the misplaced gem in question.
Thanks to this thread for the solution.