> > >
brew install ruby
brew install libxml2
gem install nokogiri -- --with-xml2-include=/usr/local/Cellar/libxml2/2.9.4/include/libxml2 --use-system-libraries
gem uninstall -aIx
gem sources --add https://gems.ruby-china.org/ --remove https://rubygems.org/
bundle config mirror.https://rubygems.org https://gems.ruby-china.com
brew install libexif
CPATH=$(brew --prefix libexif)/include gem install exif