How to fix homebrew error invalid active developer path after upgrade to OS X El Capitan
Run the following commands to fix the above error:
sudo xcode-select --install
sudo xcode-select -switch /
Answer on Homebrew/legacy-homebrew#23500
May also have to do this:
sudo chown -R $(whoami):admin /usr/local
cd $(brew --repo); git fetch; git reset --hard origin/master; brew update
Uses brew install terminal-notifier https://github.com/julienXX/terminal-notifier
https://gist.github.com/boneskull/c578346195eed967e4dd21e4f26e5f04