I have a desktop machine that keeps going into suspend. I want this machine to never go into suspend.

First execute this

systemctl status sleep.target suspend.target hibernate.target hybrid-sleep.target

You will get four answers – look for the entries “Loaded: loaded”

Now execute

sudo systemctl mask sleep.target suspend.target hibernate.target hybrid-sleep.target

and check it again

systemctl status sleep.target suspend.target hibernate.target hybrid-sleep.target

This time you should get “Loaded: masked” in the replies

Tested on Fedora 40