How to tell which version of a gem a rails app is using

Question

I'm investigating a rails app - the prod server has two version of a specific gem installed, how can I tell which version the prod app is using?

user_8732875 · Answer

bundle show gemname I.e for devise you have to write like

bundle show devise

and it will printout the current gem version.

user_2534479 · Answer

In newer version, used bundle show gem_name

[DEPRECATED] use `bundle info gem_name` instead of `bundle show gem_name`

user_51387 · Answer

If you use bundler, then you can get the version using:

bundle info [gemname]