How to use Homebrew on a Multi-user MacOS Sierra Setup

I have a Mac that is shared between two engineers. Both have separate user accounts. Both need to run brew update and brew install... occasionally.

How do I set this up without getting errors like: /usr/local must be writable!?

Yeah, I could have UserA take over the permissions of /usr/local every time he wants to use brew (and same with UserB), but that seems like a lot of unnecessary trouble.

You can also change the group permissions to admin or another group that both of your users are in:

chgrp -R admin /usr/local
chmod -R g+w /usr/local

Original source: https://gist.github.com/jaibeee/9a4ea6aa9d428bc77925

UPDATE:

In macOS High Sierra you can't change the owner, group or permissions of /usr/local. So you have to change the group and permissions of the subfolders:

chgrp -R admin /usr/local/*
chmod -R g+w /usr/local/*

UPDATE September 2018, High Sierra 10.13.6

1. Determine the path of the brew prefix, ie. the path that will be used to store files related to working with homebrew
2. Check that all users on the system who need access to brew are in the admin group
3. Optional Add a user to the admin group if a user needs access to brew

   Will require access / privileges to use the sudo command

4. Set the brew prefix path to be recursively owned by the admin group
5. Set the brew prefix path to be recursively writable by all users who are in the admin group
6. Verify the permissions of the brew prefix
7. brew 🍻

echo $(brew --prefix)
echo $(groups $(whoami))
sudo dseditgroup -o edit -a $(whoami) -t user admin
sudo chgrp -R admin $(brew --prefix) 
sudo chmod -R g+rwX $(brew --prefix)
ls -lah $(brew --prefix)

Every answer that tries to hack permissions, or use sudo is wrong.

Do not use sudo and do not share a single brew installation across user accounts.

The correct answer per the Homebrew docs is to use zero or one global brew installation on a machine, and for all other users install a local version of brew.

This is especially important on Mac, but works on Linux too.

This can be done by one of the following approaches

1. Git approach: doing a git checkout of the source repo
2. Untar-anywhere approach: expanding a tarball into some directory – owned by your user

Git approach

For the git approach you'll need to clone brew.

Arbitrarily choosing my user home directory for my checkout:

cd $HOME
git clone https://github.com/Homebrew/brew.git
./brew/bin/brew tap homebrew/core

Untar-Anywhere Approach

As documented at docs.brew.sh, run this command in your home directory, which will create ~/brew.

cd $HOME
mkdir brew && curl -L https://github.com/Homebrew/brew/tarball/master | tar xz --strip 1 -C brew

Finishing up

For either installation method, you'll need to change your PATH to prefer the new brew bin directory, adding something like this to your shell's dot file.

export PATH=$HOME/brew/bin:$PATH >> ~/.zshrc # or ~/.bashrc

Then running this to reload and test

exec $SHELL
which brew # see that brew is found in your path

Since this is a new installation, you have to install all your desired brew packages (again).