I read several instructions on upgrading RubyGems in Linux and didn’t have much success until discovering the Rubygems-Update Gem. With Rubygems-Update keeping my RubyGems version current is no longer an issue.
Using one recommended upgrade approach
$ gem update —system
displayed the Debian “set the REALLY_GEM_UPDATE_SYSTEM environment variable” error message.
Fortunately it was then I discovered the Rubygems-Update Gem.
$ sudo gem install rubygems-update
$ sudo update_rubygems
Rubygems-update installed and RubyGems updated!
$ gem env
confirms we’re up to speed with the latest RubyGems.
Big thanks to Sameera Gyan and his post Upgrading Ruby Gems on Ubuntu Linux. And of course, thank you to the authors of the RubyGems-Update Gem!