Fixing a Mac Onboarding Script Frozen by the Homebrew 6.0 Update
makedream29. Juli 2026
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Computing/Software
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When I arrived at work this morning, I was greeted by dozens of Slack messages reporting that our new hire onboarding script was frozen. Opening up the terminal revealed the culprit: the script was hanging indefinitely during the brew install process, waiting for user input.
With the release of Homebrew 6.0, interactive user prompt policies (Ask mode) and standard input (stdin) blocking have been tightened. While this isn't an issue when a human runs commands manually in an interactive session, running it in the background via a shell script causes the terminal to fall into an I/O deadlock.
If your own workflow is getting derailed by team members constantly asking for help with their environment setup, it's time to hardcode a few environment variables and error handlers directly into your script.
Homebrew 6.0 causes unexpected I/O stalls when installing packages without a TTY (interactive terminal) connection. To block terminal hangs and ensure a completely unattended execution environment, you need to explicitly declare dedicated environment variables at the very top of your script.
Adding the following variables to the top of your script will disable all interactive prompts and hint outputs, except for administrator privilege requests.
`bash
#!/usr/bin/env zsh
export NONINTERACTIVE=1
export HOMEBREW_NO_ENV_HINTS=1
export HOMEBREW_ACCEPT_OUTDATED_CAVEATS=1
export HOMEBREW_NO_AUTO_UPDATE=1
export HOMEBREW_NO_INSTALL_CLEANUP=1
if [[ -f "/opt/homebrew/bin/brew" ]]; then
eval "(/usr/local/bin/brew shellenv)"
else
/bin/bash -c "(/opt/homebrew/bin/brew shellenv)"
fi
safe_brew_install() {
local formula="{formula}" &>/dev/null; then
echo "Already installed: {formula}"; then
echo "Error occurred: Failed to install ${formula}" >&2
return 1
fi
fi
}
safe_brew_install "git"
safe_brew_install "jq"
`
If you prefer using Homebrew's built-in configuration file brew.env instead of .zshrc, make sure to omit the export keyword and write key-value pairs like HOMEBREW_NO_ENV_HINTS=1 to avoid syntax errors.
Starting with version 6.0, the 'Tap Trust Model' is applied by default for supply chain security reasons. Unverified external custom taps or outdated packages using MD5 or SHA-1 hashes are blocked from loading altogether.
Formulae used for internal tool distribution must specify a SHA-256 digest, and they need to pass the brew audit --strict check to prevent breaking your CI/CD pipelines.
`ruby
class InternalApiCli < Formula
desc "사내 인프라 API 제어 및 배포 자동화 CLI 도구"
homepage "https://internal.company.net/docs/cli"
url "https://internal.company.net/downloads/cli/v2.4.0/internal-api-cli-2.4.0.tar.gz"
sha256 "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
license "Proprietary"
depends_on "jq"
def install
bin.install "internal-api-cli"
end
test do
assert_match "version 2.4.0", shell_output("#{bin}/internal-api-cli --version")
end
end
`
Hardcode an SPDX-compliant license identifier (license "Proprietary") alongside exact url and desc fields inside your internal distribution Formula file (internal-api-cli.rb). It helps to set up your CI/CD pipeline to automatically extract the hash with shasum -a 256 after downloading the file and update it using sed.
On developers' local Macs, running brew trust company/tools once will register the internal tap as a trusted source, allowing installations without security warnings.
If a VS Code terminal or an older terminal emulator is running as an Intel (x86_64) binary, uname -m will return x86_64 even if you're on an M-series Mac. Installing Homebrew packages under this state will place x86 binaries under /usr/local, throwing errors like mach-o file, but is an incompatible architecture.
You need conditional logic to check if the terminal environment is running under Rosetta 2 and immediately re-launch the process natively as arm64.
`bash
#!/usr/bin/env zsh
SYSTEM_ARCH="(sysctl -n sysctl.proc_translated 2>/dev/null || echo "0")"
if [[ "{SYSTEM_ARCH}" == "x86_64" && "0" "{SYSTEM_ARCH}" == "x86_64" && "${IS_TRANSLATED}" == "0" ]]; then
HOMEBREW_PREFIX="/usr/local"
else
echo "Unsupported architecture: ${SYSTEM_ARCH}" >&2
exit 1
fi
eval "{HOMEBREW_PREFIX}/bin/brew shellenv)"
`
If querying the kernel parameter sysctl -n sysctl.proc_translated returns 1, you are in a Rosetta 2 environment. Executing exec arch -arm64 /bin/zsh "$0" "$@" in this case switches the entire script to an arm64 shell, ensuring that the correct binaries are installed under /opt/homebrew.
When developers have different Homebrew versions and varying installed packages, the classic "it works on my machine" scenario inevitably repeats itself. Combining a declarative Brewfile with brew bundle check inside your script allows new hires to complete their entire setup with a single command.
`bash
#!/usr/bin/env zsh
set -euo pipefail
export NONINTERACTIVE=1
export HOMEBREW_NO_ENV_HINTS=1
export HOMEBREW_BUNDLE_NO_UPGRADE=1
DOTFILES_REPO="https://github.com/company/dotfiles.git"
TARGET_DIR="$HOME/.dotfiles"
if ! command -v brew &>/dev/null; then
/bin/bash -c "(/opt/homebrew/bin/brew shellenv)"
fi
if [[ ! -d "{DOTFILES_REPO}" "{TARGET_DIR}" pull origin main
fi
BREWFILE_PATH="{BREWFILE_PATH}" &>/dev/null; then
echo "All dependencies in Brewfile are up to date."
else
brew bundle install --file="${BREWFILE_PATH}"
fi
`
After syncing the internal Dotfiles repository to $HOME/.dotfiles, first run brew bundle check to verify if there are any uninstalled packages. By configuring brew bundle install to execute only when missing packages are detected, running the script multiple times will consistently maintain the exact same environment.