Determine which version of a gem is installed?
gem list
should give you a list of all your gems with version number in brackets behind it
StackOverflow has the answer and it might be a more useful place (for you) for Ruby architecture questions (they're still welcome here)
gem outdated
Not being a Ruby dev or having any gems installed, I'm not sure this is going to give you exactly what you're after but it should show you which ones need attention.
Otherwise I would have suggested gem query <package>
(searches local) and gem query --remote
to see available versions. If you only need local gem versions, the first aught to do.
You can do it like this:
bundle info { gem name }
Or look in Gemfile.lock
:
grep { gem name } Gemfile.lock