Upgrading from Yosemite to El Capitan

Run: brew update

Fix permissions when you get this:

cjsMBP15:~ cj$ brew update
Error: The /usr/local directory is not writable.
Even if this directory was writable when you installed Homebrew, other
software may change permissions on this directory. Some versions of the
"InstantOn" component of Airfoil or running Cocktail cleanup/optimizations
are known to do this.

You should probably change the ownership and permissions of /usr/local
back to your user account.
  sudo chown -R $(whoami):admin /usr/local
cjsMBP15:~ cj$ 

Run: sudo chown -R $(whoami):admin /usr/local

- Xcode Install 
 Open xcode - accept terms and conditions
 close xcode

-Install xcode commandline tools	
Run: xcode-select --install 
Run: brew update
Run: brew upgrade rbenv ruby-build
Run: brew prune
Run: brew doctor
Run: bundle install  -- (on a project)
 --  No issues with my main laptop, but my older one required to force-link some brew libaries like QT and OpenSSL