sudo gem install sass
Fetching: sass-3.4.21.gem (100%)
ERROR: While executing gem ... (Errno::EPERM)
Operation not permitted - /usr/bin/sass
gem install sass
Fetching: sass-3.4.21.gem (100%)
ERROR: While executing gem ... (Gem::FilePermissionError)
You don't have write permissions for the /Library/Ruby/Gems/2.0.0 directory.