How to Repair a Linux System That Won't Boot from a Live USB
Using chroot, to run repair commands on your real installation.
A Live USB gives you a complete, working Linux system, without touching your hard drive, from which you can repair your damaged real installation.
Preparation
- Create a bootable USB drive with the same distribution you have installed (or any recent distribution, for rescue tools).
- Boot from it → "Try without installing" (not "Install").
Accessing your installed system from the Live environment
sudo fdisk -l
Identify your actual root partition (not the USB's) → mount it:
sudo mount /dev/sdXN /mnt
"Entering" your real system to repair it (chroot)
sudo mount --bind /dev /mnt/dev
sudo mount --bind /proc /mnt/proc
sudo mount --bind /sys /mnt/sys
sudo chroot /mnt
From here, the commands you run (reinstalling GRUB, repairing packages) affect your real system, not the Live one — it's like being "inside" your damaged installation but with working tools.
Tip: combine this with our GRUB guide if the specific problem is the boot manager — chroot is the necessary previous step to run repair commands on your real system.
Exiting when you finish
exit
sudo umount /mnt/dev /mnt/proc /mnt/sys /mnt
sudo reboot
Frequently asked questions
What exactly is chroot?
It's a technique that lets you temporarily 'enter' your real installed system (mounted from the Live environment) to run repair commands as if you were normally booted into it.
Is doing this risky?
It's a standard recovery technique, safe if you follow the steps in order — the main risk is mounting the wrong partition, so properly confirm which is your actual root partition before continuing.