Como remover barris desatualizados do Homebrew?

Estou usando o homebrew-cask para manter meu ecossistema de aplicativos atualizado. É ótimo ao manter vários computadores em casa, em viagens ou em trânsito.

No entanto, quando alguns pacotes estão sendo atualizados (como o Google Chrome), acabo tendo diferentes versões simultâneas instaladas (e que são vistas pelo sistema operacional):

$ ls / opt / homebrew-cask / Caskroom / google-chrome / canal estável mais recente

Isso acontece ao atualizar um barril:

$ ls -l /opt/homebrew-cask/Caskroom/tunnelblick
total 0
drwxr-xr-x 5 foo staff 238 Mar 11 07:42 3.3.0
drwxr-xr-x 5 foo staff 238 May 13 13:53 3.3.2
[13:00:40] foo at bar in ~
$ brew cask install --force tunnelblick
==> Caveats
For security reasons, Tunnelblick must be installed to /Applications and will request to be moved at launch.

==> Downloading https://downloads.sourceforge.net/project/tunnelblick/All%20files/Tunnelblick_3.3.4.dmg
######################################################################## 100.0%
==> It seems there is already an App at '/Applications/Tunnelblick.app'; not linking.
🍺  tunnelblick installed to '/opt/homebrew-cask/Caskroom/tunnelblick/3.3.4' (236 files, 20M)

$ ls -l /opt/homebrew-cask/Caskroom/tunnelblick
total 0
drwxr-xr-x 5 foo staff 238 Mar 11 07:42 3.3.0
drwxr-xr-x 5 foo staff 238 May 13 13:53 3.3.2
drwxr-xr-x 5 foo staff 238 Jun 26 13:01 3.3.4
[13:01:26] foo at bar in ~

Como mantenho apenas as mais recentes?

No Terminal, digite:

for app in $(brew cask list); do cver="$(brew cask info "${app}" | head -n 1 | cut -d " " -f 2)"; ivers=$(ls -1 "/opt/homebrew-cask/Caskroom/${app}/.metadata/" | tr '\n' ' ' | sed -e 's/ $//'); aivers=(${ivers}); nvers=$(echo ${#aivers[@]}); echo "[*] Found ${app} in cask list. Latest available version is ${cver}. You have installed version(s): ${overs}"; if [[ ${nvers} -eq 1 ]]; then echo "${ivers}" | grep -q "^${cver}$" && { echo "[*] Latest version already installed :) Skipping changes ..."; continue; }; fi; echo "[+] Fixing from ${ivers} to ${cver} ..."; brew cask uninstall "${app}" --force; brew cask install "${app}"; done

Dica: copie e cole a linha de comando acima no Terminal.