near disaster averted - "can not find /dev/by-id/xxxx"

[O. Sinclair]

Goh Lip wrote:
> On Wed, 19 May 2010 14:40:13 +0200
> "O. Sinclair" <o.sinclair at gmail.com> wrote:
> 
>> Have no idea what happened but if this helps someone landing in the
>> same trouble then it is worth the effort of documenting it.
>>
>> I am still on Karmic with all updates. Last night I was online and
>> left the computer on over the night. No problems, all worked this
>> morning. Shut it down to take it to where I am currently working (it
>> is a laptop and I am currently travelling).
>>
>> On next boot I get to the splash and then I get "BSOD" - Black Screen
>> of Death. A black monitor, no activity or message or anything.
>>
>> Reboot and go to "recovery option" that after a while ends up with
>> the line: ...can not find /dev/by-id/xxxx long string of UUID here
>>
>> I am dropped into Busybox shell and can do nothing worthwhile. I
>> reboot with a usb flash I have and can see that all works and the
>> disks are there (one disk, 3 partitions including swap). I check
>> grub.cfg, I check /etc/fstab and all LOOKS perfect. But no boot.
>>
>> I tried the 3-4 kernels and none worked. Scouted around internet for a
>> solution and there were a few suggestion ranging from rebuilding the
>> kernel to what eventually worked and was simple:
>>
>> on bootup get into the Grub menu by hitting ESC, Shift or both
>> choose a "recovery kernel",  I chose an earlier than the latest just
>> to be on safe side
>> press "e" to get to edit mode
>> replace all UUID-strings with /dev/sda(your root number), in my case
>> /dev/sda2
>> press ctrl+x to boot with those settings
>> drop to a root shell
>> run update-grub
>> reboot
>> all worked as before.... except now grub.cfg points to /dev/sda2
>> instead of /dev/uuid-string
>>
>> Phew,
>> Sinclair
> 
> You've 'sudo update-grub' and grub.cfg shows /dev/sda2?
> Strange.  You may want to double check that.
> But glad you've got this sorted out.
> 
> Regards - Goh Lip
> 
after manually editing the grub as described I dropped to a root-shell. 
So no need for "sudo" but update-grub. And yes, following that /dev/sda2 
has replaced /dev/uuid-endless-string