Booting into Rescue Mode
After a bad change, a service hangs the boot. You have console access and the root password. How do you boot once into single-user rescue mode without changing the default?
Choose one answer
Edit /etc/default/grub at the GRUB menu and add single, then press Enter.
/etc/default/grub
single
At the GRUB menu press e, append systemd.unit=rescue.target to the line starting with linux, then press Ctrl+X.
e
systemd.unit=rescue.target
linux
Choose the rescue kernel entry; it always boots with networking and all services disabled and asks for no password.
Run systemctl set-default rescue.target from the GRUB menu.
systemctl set-default rescue.target