Can I disable shutdown if pacman is running?

Question

During my last arch linux update using pacman -Syu I shut down my laptop, as I had forgotten that the update was running in the background and installing the packages.

Afterwards I could not start arch linux anymore and had to go through the time consuming (for me) process of creating a bootable usb with another laptop and using chroot to run re-run pacman -Syu in order to fix my arch linux install.

I've had similar problems before after accidentally shutting down my laptop while running a system update, so I was wondering if there is a way to display a warning that pacman is running if the shutdown process is about to be initiated.

I shut down my computer using the regular KDE Plasma "switch off" mechanism.

EDIT

As an idea; I think I might be able to write a script which first checks if pacman is running, as explained here, and then, if pacman is not running, calls the kde shutdown command that is shown here.

I can't try it out since I cannot access my Linux machine at the moment, but I'll try it out this evening.

Answer 1

I found a system-wide solution for this problem, preventing any kind of power-management: I created two pacman hooks, which prevent systemd from turning of the power (see https://askubuntu.com/a/858617).

The first one is masking the targets:

/etc/pacman.d/hooks/00-prevent-interruption-pre.hook

[Trigger]
Operation = Install
Operation = Upgrade
Operation = Remove
Type = Package
Target = *

[Action]
Description = Masking systemd targets to prevent interruption...
When = PreTransaction
Exec = /usr/bin/systemctl --runtime mask halt.target poweroff.target reboot.target kexec.target suspend.target hibernate.target hybrid-sleep.target suspend-then-hibernate.target sleep.target
Depends = systemd

And the second one is unmasking them again after all other hooks have been run:

/etc/pacman.d/hooks/99-prevent-interruption-post.hook

[Trigger]
Operation = Install
Operation = Upgrade
Operation = Remove
Type = Package
Target = *

[Action]
Description = Unmasking systemd targets to reenable power management...
When = PostTransaction
Exec = /usr/bin/systemctl --runtime unmask halt.target poweroff.target reboot.target kexec.target suspend.target hibernate.target hybrid-sleep.target suspend-then-hibernate.target sleep.target
Depends = systemd

This won't prevent you from logging out but will disable any shutdown functionality until pacman completed it's run sucessfully. So to keep pacman running I recommend you put it in a terminal multiplexer (like tmux) to prevent it from being interrupted when your terminal application is closed.