kindly help me on this whenever i go for upgrading to a new version of ruby this message comes up.   saddaafs-iMac:~ postgres$ bundle install Could not locate Gemfile saddaafs-iMac:~ postgres$ gem install bundler ERROR:  While executing gem ... (Gem::FilePermissionError)     You don't have write permissions for the /Library/Ruby/Gems/2.0.0 directory.