oh-my-zsh/plugins/cask/README.md

Cask plugin

Cask is a project management tool for Emacs that helps automate the package development cycle; development, dependencies, testing, building, packaging and more.

This plugin loads cask completion from non-standard locations, such as if installed via Homebrew or others. To enable it, add cask to your plugins array:

plugins=(... cask)

Make sure you have the cask directory in your $PATH before loading Oh My Zsh, otherwise you'll get a "command not found" error.