Interesting recovery frustrations

[Rashkae]

On 10-12-15 03:07 PM, MR ZenWiz wrote:
>
> Questions that arise from this for me are:
>
> 1. First and foremost, why do we have such an unbelievably arcane
> method of influencing or controlling the boot process?  There isn't a
> single facility to display what grub will do or what its settings are
> other than to read the fairly complex set of files used to generate
> the grub.cfg file.  Even something as simple as a
> grub-show-me-what-the-heck-yo're-going-to-do-on-the-next-boot is not
> available.
>
>    
less /boot/grub/grub.cfg

You can even ignore the warnings and go ahead and make changes directly 
to that file, keeping in mind only that changes you make this way are 
not permanent.

Conversely, pressing the Shift key during the Grub boot process to show 
the Grub menu will let you examine each possible boot item, and even 
edit them on the fly.

> 2. Is there a better way to recover form a situation like this (OS
> overwritten intentionally after being backed up, restoring the backup
> and not having it work)?  Obviously, not using the same root and boot
> partition would have been a better choice, but frankly I wasn't
> expecting this much of a headache getting back.
>
>    

I would do much as you have, however, to properly re-intall grub, I 
suspect you need to re-create your root filesystem from the live CD 
boot.  That is, mount your /, then mount your boot at the relative 
location.  ex: mkdir /mnt/root ; mount -t ext4 /dev/disk-by/id....  
/mnt/root  ; mount -t ext4 /dev/dis-by-id/.... /mnt/root/boot

Then you can run grub-install --root-directory=/mnt/root /dev/sda,

This is further explained here:
https://help.ubuntu.com/community/Grub2 (search for Reinstalling Grub2 
section.)

(Note:  according to those instructions, the home partition must also be 
mounted.  I have no idea why, but it's probably a good idea to follow 
the instructions )