Detect when Install macOS Big Sur.app installer application has launched, terminate the process and display an alert.
This project is heavily inspired by Erik Berglund's AppBlocker. It uses the same underlying idea of registering and listening for NSWorkspace notifications when app has started up and then checking the CFBundleIdentifier of the launched app to identify a Big Sur installer launch.
The binary requires at least macOS 10.9, however I've only tested this on macOS 10.13 and 10.14.
All configuration is optional. If needed, the alert title and text can be set through a configuration profile. Use com.hjuutilainen.bigsurblocker as the domain and AlertTitle and AlertText as the keys.
Download the prebuilt package and deploy with your favorite method. The package is signed and notarized.
To fully uninstall bigsurblocker, run the following (as root or with sudo):
current_user_uid=$( echo "show State:/Users/ConsoleUser" | scutil | awk '/UID :/ && ! /loginwindow/ { print $3 }' )
launchd_item_path="/Library/LaunchAgents/com.hjuutilainen.bigsurblocker.plist"
launchctl bootout gui/${current_user_uid} "${launchd_item_path}"
rm -f /Library/LaunchAgents/com.hjuutilainen.bigsurblocker.plist
rm -f /usr/local/bin/bigsurblocker
pkgutil --forget com.hjuutilainen.bigsurblocker