How to set GEM_HOME for system Ruby but not for other versions?

[reitermarkus]

On macOS, the default system Ruby needs sudo to install Gems, but now, when I set GEM_HOME, rbenv will install Gems for any version inside GEM_HOME, instead of keeping separate directories for each Ruby version.

How can I set a custom GEM_HOME for only the system Ruby?

[jeremy]

If you're setting GEM_HOME so you can install gems without needing to sudo, I'd recommend using gem install --user-install instead.

[Nakilon]

@jeremy does rbenv install gems to different folders per ruby version with that --user-install flag?

[jeremy]

RubyGems installs to Gem.user_dir when --user-install is passed. I did a web search for docs and took at look at the code on GitHub, and user_dir does include the Ruby version. Check out http://guides.rubygems.org/faqs/#user-install, for example.

Note that you have --install-path and --bin-path at your disposal, too. I'd recommend looking at RubyGems source code to dig much further, since these are poorly documented and undocumented.