How to disable suspend on Ubuntu 20.04 (systemd) via CLI

After some more searching, I found the correct answer:

In /etc/systemd/logind.conf add the following lines at the bottom:

HandleSuspendKey=ignore
HandleHibernateKey=ignore
HandleLidSwitch=ignore
HandleLidSwitchExternalPower=ignore
HandleLidSwitchDocked=ignore

and run

systemctl restart systemd-logind

to activate the new settings.

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