I run a headless Pi in a weather station using cellular data. Every night after midnight it does an 8MB download - I don't know what it is, but that's what vnstat tells me. Being as how the system runs on cellular I'd like to kill that.
Had a look in /etc/cron.daily and found a script called apt. It seems to call apt-get update which coincidentally downloads about 8MB... when I run it manually. I am not keen to hack the script because it has lots of variables and parameters and ifs and stuff. Life would get a bit ugly if I kill the system.
So I am leaning towards just getting rid of the script altogether. Perhaps someone knows something about this? I am using DietPi