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?

Answer 1

try this one for local gem :

gem list gemname | grep -P '(^|\s)\Kgemname(?=\s|$)'

If you use bundle:

bundle exec gem list gemname | grep -P '(^|\s)\Kgemname(?=\s|$)'

Answer 2

There's also a list in Gemfile.lock, located in the root directory of your app.

For this reason I leave Gemfile.lock out of my .gitignore. This has saved me more than once when I forgot to specify the gem version in GemFile, and a gem got updated with breaking changes.

Answer 3

If you use bundler, then you can get the version from

bundle show [gemname]

Answer 4

bundle exec gem which gem_name

Is probably what you can use:

$› bundle exec gem which rails
/Users/xxxx/.rvm/gems/ruby-2.1.2@gemset/gems/railties-4.1.7/lib/rails.rb

Answer 5

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

bundle show devise

and it will printout the current gem version.

Answer 6

It took me longer than expected to find and sort through this information so I wanted to post it here in one place for others to view. I also wanted to clarify this a bit for Rails 3:

• script/about has been replaced with rake about The details are here. If you are interested a list of all the command line changes for Rails 3 they can be found here.

• rake gems does not work in Rails 3. Instead you should use bundle show

As an example, you can save all versions of your gems to a file for viewing with:

gem list > all_gems.txt

and you can see what versions your Rails app is using with:

bundle show > project_gems.txt

Using an editor like Vim you can easily use vimdiff to see the changes