Remove version of Ruby/RubyGems and gems on MacOS properly

Question

I recently installed a version of Ruby (and RubyGems) via homebrew on my Mac because the RubyGems that comes installed on Mac doesn't let you install gems due to permissions issues. I followed the instructions in the top answer in this thread: You don't have write permissions for the /Library/Ruby/Gems/2.3.0 directory. (mac user)

After installing some gems, I realized that I don't need this version of Ruby and RubyGems anymore, so I ran brew uninstall ruby to get rid of them (I assume RubyGems gets deleted along with Ruby). However, I checked and it appears the gems I had installed are still in /usr/local/lib/ruby/gems/2.7.0. Can I just delete the usr/local/lib/ruby folder, and is this the correct way of going about it? I don't know if the default RubyGems that comes with MacOS uses this folder.

Answer 1

Basically when you run rbenv versions it will display all your ruby versions including the one installed by default (system).

• system ruby usually located in /usr/local/lib/ruby/gems/2.5.1
• rbenv ruby default location is inside user path ~/.rbenv/versions/2.5.1/gems

to uninstall ruby using rbenv you need to remove the specific version e.g rbenv uninstall 2.5.1

I suggest that you leave your ruby system installation, but you can remove all the gems inside the ruby system path manually /usr/local/lib/ruby/gems/2.5.1.

Answer 2

I'm the author of that top post in the link you mentioned. You are correct that Homebrew installs gems in /usr/local/lib/ruby/gems/2.7.0. You can confirm that in two ways:

• You can run brew info ruby, and then visit the Formula page that's displayed: https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/ruby.rb This is the line of code where the Rubygems directory is defined: https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/ruby.rb#L48

• You can install Ruby again with Homebrew, and you should see this section in the terminal output:

By default, binaries installed by gem will be placed into:
  /usr/local/lib/ruby/gems/2.7.0/bin

You may want to add this to your PATH.

I wrote about this in the Homebrew section of my definitive guide to installing Ruby gems on a Mac.

The system Ruby is NOT installed in /usr/local/lib/ruby. It is in /Library/Ruby/Gems/2.6.0. You can safely remove the /usr/local/lib/ruby directory. On a fresh macOS installation, the /usr/local directory is empty.

You can then check if Homebrew is still healthy by running brew doctor.

Answer 3

/usr/local/lib/ruby/gems/2.7.0 used to be brew default install path. Now they have changed it to /opt/homebrew/lib/ruby/gems/2.7.0. So you can delete the previous folder under /usr without a problem.