Do you want bundle update
You can add a gem name if you want to update a specific one using bundle update will_paginate
Here is a more detailed tutorial: http://gembundler.com/rationale.html
You need a subsection called "Updating the Gem Without Changing the Gemfile".
If you included a gem in the Gemfile with a git outline (and you did not specify any directive that would prevent updating, such as version number), it will update the gem based on the provided source. You will need to do this everywhere. Updates do not sync with your version control applications.
Here is a guide specific to git: http://gembundler.com/git.html
If you only need a specific commit, you need to add an argument :ref with a hash.
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