Recently I was persuaded by a message from my Homebrew update process to (unthinkingly) run
softwareupdate --all --install --force
forgetting that among the pending updates I had was the problematic 10.15.4 update. I literally (used correctly) cannot afford to have a bricked or compromised Mac, and so far I've had no problems, but I'd rather be sure.
Is there a way to undo
softwareupdate (I haven't yet rebooted)?