Before we dive in all the steps needed on how to create a formula, that you will use locally (ergo, not uploading it to homebrew public list), let’s briefly explain what is tap and formula in Homebrew.

Formula:

A formula is a package definition written in Ruby. A formula provides instructions and metadata for Homebrew to install a piece of software.

So basically a formula is a Ruby file, needed to install and run whatever you want in your machine. It links to a repo path, (yours). Doing a brew create xxxx.tar.gz creates the formula (Ruby file), the tar.gz is the zipped link of the project with the code you want to install in your machine (your repo); this gets clear in the steps bellow.

Tap:

A Git repository of Formulae and/or commands

This is how homebrew makes the reference or connection of your github repo referred in your formula (the ruby file) and saves it in a retrievable path:

/usr/local/Homebrew/Library/Taps/homebrew/homebrew-core/Formula/YOUR-RUBY-FORMULA-HERE

Ok, so let’s begin!

Steps to reproduce:

1.- create a github repo where you are going to place the script or file you will like to run in brew for example: unsign-xcode

2.- add the file where your script is to the repo (don’t add file extension) and also grantpermission to it: chmod +x and push the commit. I’ve created a file called unsign-xcode for this example.

3.- add a tag version to the file: v1.0.0 (for example) and push the tag

4.- go to releases in your repo page in GitHub, select tags and in the section tar.gz right click and select “Copy link address”

5.- now, create the formula (repeat this step everytime you update the version from the files in this repo), this step will create the Ruby file mentioned before:

  brew create (paste the link copied before) 

For example:

  brew create https://github.com/phynet/unsign-xcode/archive/v1.0.0.tar.gz

6.- next, it’s turn to create a new repo, this time for the homebrew formula created in step 5. In this case will be called: homebrew-unsign-xcode

7.- clone it empty and try to move the ruby file created in step 5 to this new repo. The formula file is located in:

/usr/local/Homebrew/Library/Taps/homebrew/homebrew-core/Formula/unsign-xcode.rb

8.- open the file and edit it removing the line where test text is placed and leave only the code with install, there’s where you’re going to add bin.install with the name of the file:

   def install
     bin.install "unsign_xcode"
   end

9.- add the file to git, commit and push

Note: from here, this steps are going to be similar to any homebrew process to install code

10.- once pushed go to terminal and tap it using a reference to the repo from step 1

    brew tap phynet/unsign-xcode

11.- now try to install using brew command

    brew install unsign-xcode

11.1.- if a message like this one appears:

    Error: unsign-xcode 1.0.3 is already installed
    To upgrade to 1.0.4, run `brew upgrade unsign-xcode`

run the command brew update and it will automatically update to the tag version for the repo updated before.

12.- To use it type the command:

 unsign-xcode

And there you have it 😀

BTW: this is the repo for my unsign-xcode command. https://github.com/phynet/unsign-xcode.