Followed the instructions in that post.
I think I’m using grub.
UPDATE
Amazing, it seems I’m using systemd
> [[ -d /run/systemd/system ]] && echo "using systemd"
using systemd
> ps 1
PID TTY STAT TIME COMMAND
1 ? Ss 0:02 /usr/lib/systemd/systemd --switched-root --system --deserialize=47
I’ll try to change to grub.