Homebrew on the lab machines

The PLSE-managed machines (whale and pipsqueak) keep their system packages minimal on purpose: patching, endpoint protection, a compiler, and a handful of basics. Nobody gets sudo for a research project, and nobody should need it. Instead, each user can run their own Homebrew in their home directory. It gives you current versions of git, python, node, rust, tmux, vim, and a few thousand other packages, and nobody else’s setup can break yours.

This page is the recipe. It takes a few minutes, and it works without sudo.

Install

Run these four commands, exactly as written:

git clone https://github.com/Homebrew/brew ~/.brew/Homebrew
mkdir -p ~/.brew/bin ~/.brew/etc/homebrew
ln -s ../Homebrew/bin/brew ~/.brew/bin/brew
echo "HOMEBREW_MAKE_JOBS=$(( ($(nproc) + 1) / 2 ))" \
  > ~/.brew/etc/homebrew/brew.env

That’s it. The first line is Homebrew itself. The symlink is the trick: brew decides where its packages live from the path it was run by, so ~/.brew/bin/brew makes ~/.brew the prefix. The last line caps how many parallel jobs a source build may use (more on that below).

Then put it on your PATH. Add this line to the end of ~/.bashrc (or ~/.zshrc if you use zsh):

eval "$(~/.brew/bin/brew shellenv)"

Log out and back in, then check:

brew --prefix      # prints /home/<you>/.brew
brew update
brew analytics off
brew install ripgrep
rg --version

The first brew command you run downloads Homebrew’s own portable Ruby, so it takes a little while. After that, most installs are “bottles”: prebuilt binaries that unpack in seconds.

Why exactly `~/.brew`

Homebrew’s Linux bottles are built for /home/linuxbrew/.linuxbrew, and that path is baked into their binaries. Homebrew can relocate a bottle to a different prefix, but only one that is no longer than the original, 26 characters. /home/<you>/.brew fits for any username up to fourteen characters. Pick a longer path and every bottle that needs relocating builds from source instead, turning a ten-second install into one that takes minutes or hours.

So: do not rename it, and do not run brew through the repository path (~/.brew/Homebrew/bin/brew), which would make the repository the prefix and hit the same problem. Always ~/.brew/bin/brew, or just brew once it is on your PATH.

Be a good neighbor

These are shared machines with no scheduler and no quotas. A few packages have no bottle and must build from source, and a big build at full parallelism can eat a 128-thread box. Two things keep that in check:

The brew.env line from the install caps a build at half the machine’s threads, for the build systems that honor Homebrew’s job count (make and friends; not every formula’s does). Homebrew reads that file on every run, so it applies in scripts and over ssh too, not just in your shell.
Run long builds under nice, as with any big job here, which covers the builds the cap does not:
```
nice brew install some-big-formula
```

What to expect

Disk. A prefix with a few dozen packages runs to about a gigabyte. A compiler toolchain or TeX runs to several. Homes on these machines have plenty of room, but brew cleanup now and then keeps old versions from piling up.
Wipes. These machines are disposable. When one is reinstalled, home directories go with it, and so does your ~/.brew. That is by design: your setup is yours to rebuild in a few minutes with the recipe above, and nobody has to reconstruct a shared toolchain.
Doctor. brew doctor should report “Your system is ready to brew.” If installs keep building from source, check that brew --prefix prints exactly /home/<you>/.brew.
Starting over. Everything lives under ~/.brew, plus a download cache in ~/.cache/Homebrew. Remove both and the eval line from your shell startup, and it is gone.

Other machines