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gem outdated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.

If your gem's name is compass, then you could run:

gem list | grep compass

It will give you a list of gems, containing the phrase compass, and corresponding versions.

You can do it like this:

bundle info { gem name }

Or look in Gemfile.lock:

grep { gem name } Gemfile.lock

To add to @Belogron’s answer you can use

gem list MyGem

To list the installed versions of MyGem

You can then type

gem which MyGem

To display the specific version that is being used.

You can do it as follow:

bundle info <gem name>

gem -v

It works for me. Checked in deepin 15.9.1(debian distro)