macOS: zsh: command not found: brew

Hi, it's BlueByte. If brew says "command not found" right after installing, don't reinstall — Homebrew is there, your shell just doesn't know where to look. On Apple silicon it lives somewhere the default PATH doesn't include. Let's confirm that's the issue and add it once, for good.

What the error means

Right after installing Homebrew, running it fails:

zsh: command not found: brew

Homebrew is installed — the shell just does not know where to find it, because its location is not on your PATH. The installer even prints the two lines you need at the end of its output, and this happens when you miss them or open a new terminal that never ran them.

Why the shell can't find brew

On Apple silicon Macs, Homebrew installs to /opt/homebrew, which is not on the default PATH. On older Intel Macs it installs to /usr/local, which usually is — so the same install "just works" on Intel and appears broken on Apple silicon. The other reasons a working setup breaks: you added the PATH line to the wrong file (~/.zshrc in a non-interactive context, say), or to a shell you are no longer using after switching from bash to zsh.

Confirm it's PATH, and find where brew lives

Check Homebrew is actually installed and where, then which shell and architecture you run:

ls /opt/homebrew/bin/brew /usr/local/bin/brew 2>/dev/null
echo $SHELL
uname -m

arm64 from uname -m means Apple silicon (/opt/homebrew); x86_64 means Intel (/usr/local). $SHELL tells you which profile file to edit. If ls finds the binary but the shell cannot, it is purely a PATH problem.

Add Homebrew to PATH, permanently

1. Add Homebrew to the current shell right now:

eval "$(/opt/homebrew/bin/brew shellenv)"

brew works immediately in this terminal.

2. Make it permanent for every new shell by appending the same line to your zsh profile:

echo 'eval "$(/opt/homebrew/bin/brew shellenv)"' >> ~/.zprofile

3. On an Intel Mac, use /usr/local/bin/brew instead:

eval "$(/usr/local/bin/brew shellenv)"

A real case: a new M-series MacBook

You install Homebrew on a new M-series MacBook, close the installer's terminal, open a fresh one, and brew --version says "command not found". ls /opt/homebrew/bin/brew shows the binary exists and uname -m prints arm64, so it is only a PATH issue. You run echo 'eval "$(/opt/homebrew/bin/brew shellenv)"' >> ~/.zprofile, open a new terminal, and which brew now returns /opt/homebrew/bin/brew. Every future shell finds it because the line lives in your login profile.

Confirm a fresh terminal finds it

Open a new terminal and confirm brew is found and on PATH:

which brew        # /opt/homebrew/bin/brew
brew --version

If a fresh terminal finds it, the profile change took effect for all future sessions — not just the one you edited in.

Keep it from recurring

Add the shellenv line to your profile once, right after installing, and keep it in ~/.zprofile (modern macOS uses zsh). If you sync dotfiles across machines, guard the path so an Intel and an Apple-silicon Mac each load the right one.

How this differs from a real brew error

"command not found: brew" is a PATH problem — the program exists but the shell cannot find it. That is different from a Homebrew error like "Permission denied" or a failed formula install, where brew is found and runs but the operation fails. When the shell can't find brew at all, it is PATH — add the shellenv line.