brew/docs/Shell-Completion.md

Homebrew Shell Completion

Homebrew comes with completion definitions for the brew command. Some packages also provide completion definitions for their own programs.

zsh, bash and fish are currently supported. (Homebrew provides brew completions for zsh and bash; fish provides its own brew completions.)

You must configure your shell to enable the completion support. This is because the Homebrew-managed completions are stored under HOMEBREW_PREFIX, which your system shell may not be aware of, and because it is difficult to automatically configure bash and zsh completions in a robust manner, so the Homebrew installer cannot do it for you.

Configuring Completions in bash

To make Homebrew's completions available in bash, you must source the definitions as part of your shell startup. Add the following to your ~/.bashrc file:

if type brew 2&>/dev/null; then
  for completion_file in $(brew --prefix)/etc/bash_completion.d/*; do
    source "$completion_file"
  done
fi

Configuring Completions in zsh

To make Homebrew's completions available in zsh, you must get the Homebrew-managed zsh site-functions on your $FPATH before initialising zsh's completion facility. Add the following to your ~/.zshrc file:

if type brew &>/dev/null; then
  FPATH=$(brew --prefix)/share/zsh/site-functions:$FPATH
fi

This must be done before compinit is called. (Note: if you are using Oh My Zsh, it will call compinit for you, so this must be done before you call oh-my-zsh.sh.)

You may also need to forcibly rebuild zcompdump:

  rm -f ~/.zcompdump; compinit

Additionally, if you receive "zsh compinit: insecure directories" warnings when attempting to load these completions, you may need to run this:

  chmod go-w "$(brew --prefix)/share"

Configuring Completions in fish

No configuration is needed in fish. Friendly!