CompTIA Linux+ (XK0-006)System ManagementHard
A server fails to boot and drops to a 'grub rescue>' prompt with the error 'file not found' due to a corrupted /boot/grub2 directory. Which sequence of commands at the grub rescue prompt correctly loads the necessary modules and boots into a normal GRUB environment for further troubleshooting?
- Aset root=(hd0,1); insmod normal; normal
- Bgrub-install /dev/sda; update-grub; reboot
- Cls; ls (hd0,1)/; boot
- Dlinux /vmlinuz root=/dev/sda1; initrd /initrd.img; boot
Show answer & explanationAnswer & explanation
Correct answer: A. set root=(hd0,1); insmod normal; normal
At the minimal grub rescue> prompt, one sets the root device to the partition holding the GRUB files, then loads and invokes the 'normal' module to restore full GRUB menu functionality. The 'linux'/'initrd' commands require the full grub> environment, and grub-install/update-grub require a working shell that isn't available at rescue prompt.
Why the other options are wrong
- B. Requires a working OS shell, which is unavailable at the rescue prompt.
- C. Only lists devices and files; the plain 'boot' command has nothing loaded to boot.
- D. These commands require the full grub> shell, not available at rescue>.
GRUB Rescue Prompt Recovery
The minimal grub rescue> environment only supports basic commands like ls, set, and insmod; loading the 'normal' module restores full GRUB menu functionality.
- grub rescue> is a minimal fallback shell
- set root= points to the partition holding grub files
- insmod normal loads full GRUB functionality
- 'normal' command then invokes the full menu
Memory trick: Set the root, then go Normal to escape rescue mode