====== Arranque ======


BIOS - EFI
HD
Boot Sector
Boot Loader(GRUB2)
  Kernel
  Initramfs (add driver kernel)
    Systemd
====== Apagado ======

//**systemd**//
systemctl poweroff
systemctl reboot
systemctl hibernate

//**legacy**//

poweroff
shutdown
reboot

echo b > /proc/sysrq-trigger

  * https://matoski.com/article/emergency-reboot-shutdown-linux-sysrq/


====== GRUB ======

ls /etc/default/grub

grub2-mkconfig -o /boot/grub/grub.cfg
grub2-mkconfig -o /boot/efi/EFI/xxx/grub/grub.cfg

cat /boot/grub/grub.cfg 

systemd.unit=rescue.target
systemd.unit=emergency.target