# `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`):

```sh
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)"`:

```sh
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`:

```sh
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:

```sh
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`:

```sh
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
```
