brew/docs/Shell-Completion.md

brew 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.

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

Shell completions for external Homebrew commands are not automatically installed. To opt-in to using completions for external commands (if provided), they need to be linked to HOMEBREW_PREFIX by running brew completions link.

Configuring Completions in bash

To make Homebrew's completions available in bash, you must source the definitions as part of your shell's startup. Add the following to your ~/.bash_profile (or, if it doesn't exist, ~/.profile):

if type brew &>/dev/null
then
  HOMEBREW_PREFIX="$(brew --prefix)"
  if [[ -r "${HOMEBREW_PREFIX}/etc/profile.d/bash_completion.sh" ]]
  then
    source "${HOMEBREW_PREFIX}/etc/profile.d/bash_completion.sh"
  else
    for COMPLETION in "${HOMEBREW_PREFIX}/etc/bash_completion.d/"*
    do
      [[ -r "${COMPLETION}" ]] && source "${COMPLETION}"
    done
  fi
fi

If you install the bash-completion formula, this will automatically source the completions' initialisation script (so you do not need to follow the instructions in the formula's caveats).

If you are using Homebrew's bash as your shell (i.e. bash >= v4) you should use the bash-completion@2 formula instead.

Configuring Completions in zsh

To make Homebrew's completions available in zsh, the Homebrew-managed zsh/site-functions path needs to be inserted into FPATH before initialising zsh's completion facility. This is done by brew shellenv, so if you followed the post-Homebrew installation steps, eval "$(brew shellenv)" should be in your ~/.zprofile (on macOS) or ~/.zshrc (on Linux). All you need is add the following to your ~/.zshrc if it's not already there, and, if you're on Linux, make sure it's placed after eval "$(brew shellenv)":

autoload -Uz compinit
compinit

Note that if you are using Oh My Zsh, it will call compinit for you when you source oh-my-zsh.sh. In this case, make sure eval "$(brew shellenv)" is called before sourcing oh-my-zsh.sh if you're on Linux, and you should be all set without any additional configuration.

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

Configuring Completions in fish

No configuration is needed if you're using Homebrew's fish. Friendly!

If your fish is from somewhere else, add the following to your ~/.config/fish/config.fish:

if test -d (brew --prefix)"/share/fish/completions"
    set -p fish_complete_path (brew --prefix)/share/fish/completions
end

if test -d (brew --prefix)"/share/fish/vendor_completions.d"
    set -p fish_complete_path (brew --prefix)/share/fish/vendor_completions.d
end