How to protect a process with a watchdog

Im on ubuntu, and im running a foo.sh script in the background. How to protect it from being killed by the user with sudo? How to protect this process from myself?

I want the pc to shut down after watchdog notices the script process is killed.
And cant I just kill the watchdog instead to trick this protection?

I installed watchdog, but i dont know how to use it. Please help, give me an example command.

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In case you wonder, foo.sh is a script that shuts down my pc X minutes after running, like a scheduled shutdown. I want to schedule a shutdown, but I end up canceling it later. I must stop myself from canceling it.