Hi! This is what I think but please correct me if I am wrong. 1. systemd runs systemd units for systemd shutdown.target 2. /lib/systemd/system-shutdown (shutdown.c) runs 3. /lib/systemd/system-shutdown executes /run/initramfs/shutdown (which is dracut) 4. dracut shutdown.sh performs various cleanup tasks (such as kill all remaining processes and unmount root disk) 5. /lib/systemd/system-shutdown runs scripts in the /usr/lib/systemd/system-shutdown/ folder 6. /lib/systemd/system-shutdown performs further cleanup (similar to dracut, probably some functionality duplicated with dracut, includes kill all remaining processes, unmount the root risk) and eventually halt/reboot/poweroff/kexec. Cheers, Patrick