How to create a bootable Ubuntu hard disk from an image of an Ubuntu partition?

Question

I had a dual boot SSD with Windows 7 (on primary) and Ubuntu 18.04 (on extended partition). I needed to delete the Windows partition so as to let Ubuntu use the entire HDD.

Since Ubuntu was on the extended partition, it was not possible to resize it. So, I created an image of the Ubuntu 18.04 partition using clonezilla. Then, I deleted all the existing partitions in the SSD and created a single new ext4 partition on the SSD (sda1).

Next I cloned the 18.04 partition image back to the new partition (sda1). However, I got an error message stating that it was unable to restore extended boot record into an extended partition (sda4) which existed in the SSD before creating the new partition table. I tried to use disk repair to fix the boot issue, but it failed to do so.

My question is how to create a bootable ubuntu disk (in a newly formatted/partitioned SSD/HDD) from an image of an ubuntu partition?

Answer 1

Since you write of extended partitions, I assume MBR with legacy BIOS boot style. There are several ways to recover from this situation.

"Jump-Start"

Use any tool to boot into the "dead" system. I recommend Super Grub2 Disk for ease of use.

From within the system, execute sudo grub-install /dev/yoursystemdisk and sudo update-grub and you are done.

External GRUB Install

Boot a live Linux. Mount the "dead" Linux file-system (I assume /mnt). From the live Linux, execute sudo grub-install --root-partition=/mnt /dev/yoursystemdisk and sudo grub-mkconfig /mnt/boot/grub/grub.cfg.

chroot

Boot a live Linux. Mount the "dead" Linux file-system. Bind /dev, /sys and /proc into the "dead" system. Chroot into the "dead" system, then execute the commands from the jump-start method.