Unable to run gem install XYZ on OS X El Capitan
If you’ve upgraded your computer to El Capitan and you’re getting errors while trying to install some gems, this is due to El Capitan’s introduction of SIP (System Integrity Protection).
Read more about SIP here: https://support.apple.com/en-us/HT204899
The other day I was trying to run gem install bundler and got a permissions error. Not cool.
gem install bundler
Fetching: bundler-1.13.6.gem (100%)
ERROR: While executing gem ... (Gem::FilePermissionError)
You don't have write permissions for the /usr/bin directory.
Try installing to your directory:
gem install bundler -n /usr/local/bin