Command Not Found

This feature 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 a command to install it. Using this script, you can replicate this feature on macOS:

$ when
The program 'when' is currently not installed. You can install it by typing:
  brew install when

Install

Installation instructions for your shell can be viewed by running:

brew command-not-found-init

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

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

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

    set HOMEBREW_COMMAND_NOT_FOUND_HANDLER (brew --repository)/Library/Homebrew/command-not-found/handler.fish
    if test -f $HOMEBREW_COMMAND_NOT_FOUND_HANDLER
      source $HOMEBREW_COMMAND_NOT_FOUND_HANDLER
    end
  

Requirements

This tool requires one of the following:

• Zsh (the default on macOS Catalina and above)
• Bash (version 4 and higher)
• Fish

How it works

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 --explain on your command. If it finds a match it will print installation instructions. If not, you’ll get an error as expected.