Homebrew explained

What is Homebrew

Homebrew is the missing package manager for macOS. What does that mean? In layman terms, it is like the Appstore, but for opensource softwares, which are usually used for development, like node, java, mysql, etc. But you can also install normal software like chrome, firefox, acrobat, etc.

But Homebrew is not meant for regular computer users, as it is a text-based terminal application. Meaning to use it, you need to open a terminal on your Mac, and type commands to run and use it. So it is usually meant for more tech-savvy users like developers. Though there is a user-interface software - Cakebrew to run homebrew, you’ll need to have homebrew installed first, and it still looks quite technical and not ready for non-technical users to understand.

Installation

To install homebrew, simply open a terminal in Mac and run /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

Finding Software to Install

To list the softwares available to install, run brew formulae, or go to https://formulae.brew.sh/. Formulae are the more technical or text-based softwares like java, node, etc. Casks are the softwares with user interfaces like chrome, firefox. Use brew casks to list all the software with user interfaces. For simplicity sake, we’ll address both of them as software in this article.

If you have a particular software in mind, you can run brew search <software>. If it is available, it will be listed, whether it is a formulae or cask. For example, below is the result if you run brew search java.

==> Formulae
app-engine-java            java11                     libreadline-java
google-java-format         javacc                     pdftk-java
java ✔                     javarepl
java-service-wrapper       jslint4java

==> Casks
charles-applejava          java6                      eclipse-javascript
java-beta                  eclipse-java               oracle-jdk-javadoc

If you want to get a one-liner description of the software, run brew desc <software>. E.g. brew desc java11.

openjdk@11: Development kit for the Java programming language

To get more information about it, run brew info <software>, e.g. brew info node, and it will show you the official website, the repository where this is installed from, the dependencies, whether you have already installed it, where is it installed, how many people has installed it for how many days, etc.

node: stable 17.8.0 (bottled), HEAD
Platform built on V8 to build network applications
https://nodejs.org/
/usr/local/Cellar/node/17.6.0_1 (2,016 files, 46.0MB) *
  Poured from bottle on 2022-03-07 at 11:22:54
From: https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/node.rb
License: MIT
==> Dependencies
Build: pkg-config ✔, python@3.9 ✘
Required: brotli ✔, c-ares ✔, icu4c ✔, libnghttp2 ✔, libuv ✘, openssl@1.1 ✘
==> Options
--HEAD
  Install HEAD version
==> Analytics
install: 531,246 (30 days), 1,290,818 (90 days), 4,970,569 (365 days)
install-on-request: 462,867 (30 days), 1,122,737 (90 days), 4,052,433 (365 days)
build-error: 535 (30 days)

Installing Software with Homebrew

To install it, run brew install <software>, e.g. brew install java. If it is a cask, you will need to run brew install --cask <software>, e.g. brew install --cask cakebrew.

To uninstall it, run brew uninstall <software>, e.g brew uninstall java.

By default, the formulae will be installed in the directory /usr/local/Cellar/<software>/<version>, whereas casks will be installed in the directory /usr/local/Caskroom. There will be a symlink created in /usr/local/bin/<software> so that the software is in your $PATH and can be accessible from any directory. In homebrew terms, /usr/local/Cellar is known as the Cellar. /usr/local/Cellar/<software> is known as the rack, and /usr/local/Cellar/<software>/<version> is known as the keg. So Cellar is the place where you keep everything, and each software is a rack in the cellar, and each version of the software is a keg.

Listing Software Installed with Homebrew

To list all the installed software, run brew list.

Upgrade Software Installed with Homebrew

To upgrade any of the software installed, run brew upgrade <software>, and it will upgrade the software to its latest version. Run brew upgrade to upgrade all available softwares installed by homebrew. However, if you have a specific software which you don’t want it to be upgraded, run brew pin <software>, and it will not be upgraded. To allow it to be upgraded again, run brew unpin <software>.

Updating Homebrew

To update Homebrew itself, run brew update.

Periodic Cleanup

Periodically, run brew cleanup to remove outdated files. Sometimes, when you install a software, it will install other software as dependencies. And if you uninstall the main software, the dependent software might not get uninstalled, so run brew autoremove to do that. You can run brew autoremove --dry-run to list what will be autoremoved without actually removing the unused software.

Installing Multiple Versions of the Same Software

Sometimes you want to install multiple versions of the same software, take for example NodeJs. To get the latest version of node, simply run brew install node. After installation, a symlink /usr/local/bin/node will be created, pointing to the latest node version (e.g. version 17) installed by homebrew, for example node -> ../Cellar/node/17.6.0_1/bin/node. So that when you run node on your terminal, it will be running the latest version of node. It will be updated to the latest node version when you run brew upgrade node or brew upgrade. But there might be times when you need to work on a legacy application that is running on node version 12. You can install the version 12 by running brew install node@12, and it will be installed into /usr/local/bin/node@12. But node@12 is keg-only, meaning a symlink will not be created at /usr/local/bin/node to point at it, as this symlink is reserved solely for the latest version of node. So when you run node --version, it will still point to the latest version, example version 17.

To use node12, you have to unlink the existing node by running brew unlink node, then run brew link --overwrite node@12. After that when you run node --version, you can see that it will be version 12 instead, and npm -v will also show you it is version 6.

However, if you try to unlink node@12 and link node, npm is not automatically installed, and the only way to go around it is to reinstall node by running brew reinstall node. This is due to how homebrew works and it is intentional. Source: https://github.com/Homebrew/homebrew-core/issues/34475.

Other Sources

By default, all the software available for installation are from the Homebrew repository, so it is maintained by Homebrew. There are also third-party lists you can tap from, example mongodb/brew, aws/tap. To add a third-party list, simply run brew tap <third-party-tap>, for example brew tap mongodb/brew.

To list the taps you have added, run brew tap. To find out more about the tap, like which repository is it from, and where is it installed in your system, run brew tap-info <tap-name>.

To remove a tap, run brew untap <tap-name>.

Usually, you will encounter the tap when you have a software in mind which you want to install, and the information will be available in the website of the software. For example, when you want to install the cli for AWS SAM, you can find the information to install it via homebrew at https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/serverless-sam-cli-install-mac.html.