What is the difference between the cask installation suggested in the link and the cask installation procedure suggested on the cask home page?

  $ brew tap phinze/homebrew-cask ; brew install brew-cask  

  $ brew install caskroom/cask/brew-cask

FYI: The grep in homebrew/dupes is not a newer version of the grep provided by OSX. OSX grep is the BSD variant, hb/dupes provides GNU grep. I am always shocked by how poorly BSD grep performs compared to GNU grep. I think you need to provide the `--default-names` option in order to use GNU grep in place of BSD grep.