Prevent shutdown when several users are logged in

[Spip]

Hi,
I hope this is the best section of this forum for posting my question. I was wondering if there is a simple way to prevent accidental shutdown when the following situation occurs:
Sometimes, I log in on my father's computer to run some administrations' tasks (updates...). For that, I use SSH since I'm frequently far from my parents and what I want is to prevent a shutdown run by my father. Of course, he should be able to turn off by himself if nobody else is connected.
Molly-Guard allows to prevent distant shutdown, my request is a kind of complementary software.
Does anyone know a project which could fit with this request? Do you have simple ideas to write a short code (I know bash, perl, python... I can do it by myself but tips are welcome)
Cheers,
Francois

[reed9]

Well, I don't have an exact solution for you, but maybe I can point you in the right direction. Or at least a direction, right or not.

You should be able to prevent shutdown or restart while multiple sessions are active using consolekit/policykit rules. Unfortunately, I can't find too much documentation on the issue and there have been many rapid changes. I don't know where Debian is at with them all.

For me on Arch for example, there is the file /usr/share/polkit-1/actions/org.freedesktop.consolekit.policy with entries like so

<action id="org.freedesktop.consolekit.system.stop-multiple-users">
    <description>Stop the system when multiple users are logged in</description>
    <message>System policy prevents stopping the system when other users are logged in</message>
    <defaults>
      <allow_inactive>no</allow_inactive>
      <allow_active>auth_admin_keep</allow_active>
    </defaults>
  </action>

In Ubuntu these days, it's the default that shutting down while multiple users are logged is requires admin privileges.

PolicyKit - Debian Wiki

[Spip]

Thank you for the clue. I'll look that deep inside.