System boot and GRUB

Cheat sheet

• sudo update-grub after editing /etc/default/grub
• sudo grub-install /dev/sda reinstall the bootloader
• systemctl get-default current default target
• sudo systemctl set-default multi-user.target a server with no GUI
• systemctl isolate rescue.target emergency mode
• systemd-analyze blame boot timing
• journalctl -b -1 log of the previous boot