Homebrew Command Not Found

This project reproduces Ubuntu’s command-not-found for Homebrew users on macOS.

On Ubuntu, when you try to use a command that doesn’t exist locally but is available through a package, Bash will suggest you a command to install it. Using this script, you can replicate this feature on macOS:

# on Ubuntu
$ when
The program 'when' is currently not installed.  You can install it by typing:
sudo apt-get install when

# on macOS with Homebrew
$ when
The program 'when' is currently not installed. You can install it by typing:
  brew install when

Over 5000 formulae are supported, representing more than 17000 different commands (100% of the main Homebrew repo).

Install

First, tap this repository:

brew tap homebrew/command-not-found

• Bash and Zsh: Add the following line to your ~/.bash_profile (bash) or ~/.zshrc (zsh):

  HB_CNF_HANDLER="$(brew --prefix)/Homebrew/Library/Taps/homebrew/homebrew-command-not-found/handler.sh"
  if [ -f "$HB_CNF_HANDLER" ]; then
  source "$HB_CNF_HANDLER";
  fi

• Fish: Add the following line to your ~/.config/fish/config.fish:

  set HB_CNF_HANDLER (brew --prefix)"/Homebrew/Library/Taps/homebrew/homebrew-command-not-found/handler.fish"
  if test -f $HB_CNF_HANDLER
     source $HB_CNF_HANDLER
  end

Requirements

This tool requires one of the following:

• Bash (version 4 and higher)
• Fish
• Zsh

macOS ships Bash 3.x so you must upgrade to v4.x and configure it to be used with:

brew update && brew install bash
# Add the new shell to the list of allowed shells
sudo bash -c 'echo /usr/local/bin/bash >> /etc/shells'
# Change to the new shell
chsh -s /usr/local/bin/bash

How it works

When you tap the repo you’ll get two more brew commands: brew which-formula and brew which-update. The first one uses a database file which gives you the formula you have to install in order to get a specific command. The file is generated by the second command by crawling all installed formulae and collecting their binaries. Having this as a tap means you get an up-to-date binaries database each time you run brew update.

The handler.sh script defines a command_not_found_handle function which is used by Bash when you try a command that doesn’t exist. The function calls brew which-formula on your command, and if it finds a match it’ll print it to you. If not, you’ll get an error as expected.