From Han Wiki
Installation issue on OS X
- Last tested on OS X El Capitan 10.11.5
When following the instruction for the installation of Compass website you get an error message.
$ sudo gem install compass ERROR: While executing gem ... (Errno::EPERM) Operation not permitted - /usr/bin/sass $
OS X El Capitan does not allow write access to /usr/bin in spite of the sudo command. The recommended installation target folder is /usr/local/bin. We specify this path in the installation command.
$ sudo gem install -n /usr/local/bin compass