Rails: List of Gems being used by a particular application

There are many gems installed our development machines, and we not sure which gems are a开发者_StackOverflow社区ctually being used by the application. This list is not maintained in environment.rb either. Is there a way to figure our which gems are being used by a particular application?

[EDIT]: Is it a safe way to find require in all .rb files and check in search result which gems are used in application?

Thanks, Imran

You could try the standard rake tasks rake gems (should list the gems that this rails application depends on) or rake gems:unpack (should unpack all required gems into vendor/gems).

Not that I'm aware of, this is a motivator for folks to use bundler and rvm as this can be very painful if you've adopted a project that someone else wrote.