Uninstall all installed gems, in OSX?

There are instances where I would like to revert and uninstall all previous gem installations.

For instance, I needed to assist a friend migrate their rails development machine to use RVM. As they had been previously using the system-wide gem, he was experiencing many headaches when working with multiple projects. Essentially, he was the poster-child for an RVM convert.

How can I elegantly uninstall all of the gems on his OSX system?

Rubygems >= 2.1.0

gem uninstall -aIx

a removes all versions
I ignores dependencies
x includes executables

Rubgems < 2.1.0

for i in `gem list --no-versions`; do gem uninstall -aIx $i; done

You could also build out a new Gemfile and run bundle clean --force. This will remove all other gems that aren't included in the new Gemfile.

A slighest different version, skipping the cut step, taking advantage of the '--no-version' option:

gem list --no-version |xargs gem uninstall -ax

Since you are removing everything, I don't see the need for the 'I' option. Whenever the gem is removed, it's fine.

First make sure you have at least gem version 2.1.0

gem update --system
gem --version
# 2.6.4

To uninstall simply run:

gem uninstall --all

You may need to use the sudo command:

sudo gem uninstall --all