Homebrew Caskでインストール済みのパッケージを全てアップデートするシェルスクリプト

$ brew cask update && brew cask list | xargs brew cask install
Already up-to-date.
Warning: A Cask for adobe-reader-ja is already installed. Add the "--force" option to force re-install.
Warning: A Cask for alfred is already installed. Add the "--force" option to force re-install.
Warning: A Cask for atom is already installed. Add the "--force" option to force re-install.
Warning: A Cask for bartender is already installed. Add the "--force" option to force re-install.
Warning: A Cask for bettertouchtool is already installed. Add the "--force" option to force re-install.
Warning: A Cask for betterzipql is already installed. Add the "--force" option to force re-install.
Warning: A Cask for dropbox is already installed. Add the "--force" option to force re-install.
Warning: A Cask for evernote is already installed. Add the "--force" option to force re-install.
Warning: A Cask for google-japanese-ime is already installed. Add the "--force" option to force re-install.
Warning: A Cask for intellij-idea is already installed. Add the "--force" option to force re-install.
Warning: A Cask for iterm2 is already installed. Add the "--force" option to force re-install.
Warning: A Cask for java is already installed. Add the "--force" option to force re-install.
Warning: A Cask for java7 is already installed. Add the "--force" option to force re-install.
Warning: A Cask for karabiner is already installed. Add the "--force" option to force re-install.
Warning: A Cask for mysqlworkbench is already installed. Add the "--force" option to force re-install.

Warningが嫌なら

$ brew cask update 2> /dev/null && brew cask list | xargs brew cask install 2> /dev/null

こんな感じでaliasに登録しています。

$ alias bcu='brew cask update 2> /dev/null && brew cask list | xargs brew cask install 2> /dev/null '
$ bcu

古いバージョンの削除はしないので手動で削除する必要があります。