Booting from Grub CLI

booting_from_grub_cli.md

GRUB CLI usage for boot

Boot into recovery mode using Grub cli

Entering Grub cli

After the initial BIOS splash screen, press Shift to open GRUB menu. Then press c to enter CLI mode.

You will see a terminal like following

grub> 

List disks and partitions

grub> ls

(hd0) (hd0,msdos2) (hd0,msdos1)

hd0 is the disk name. And (hd0, msdos1), (hd0,msdos2) are the partitions at /dev/sda1, /dev/sda2 respectively.

What’s all this msdos stuff? That means this system has the old-style MS-DOS partition table(MBR), rather than the shiny new Globally Unique Identifiers partition table (GPT)

List files

To list files in dev/sda2 run the following

grub> ls (hd0,msdos2)/

lost+found/ bin/ boot/ cdrom/ dev/ etc/ home/  lib/
lib64/ media/ mnt/ opt/ proc/ root/ run/ sbin/ 
srv/ sys/ tmp/ usr/ var/

Booting from GRUB

To boot into the linux image present in dev/sda2 do the following

1. grub> set root=(hd0,msdos2)
2. grub> linux /boot/vmlinuz-5.4.0-58-generic root=/dev/sda2
3. grub> initrd /boot/vmlinuz-5.4.0-58-generic
4. grub> boot

For Recovery mode

For booting into recovery mode replace Step 2 of the above process with

grub> linux /boot/vmlinuz-5.4.0-58-generic root=/dev/sda2 recovery