[Tfug] Grub rescue

[John Hubbard]

You don't need to create a password for root to be able to run things as root. Just do a 
>sudo su
And you will become root without ever having to set up a password for the root account. Way more convenient when running off of a live disk and your settings are lost after every boot. 

-john (from a mobile device)

-----Original Message-----
From: Kramer Lee <krameremark1 at gmail.com>
Sender: tfug-bounces at tfug.org
Date: Mon, 1 Nov 2010 18:03:03 
To: Tucson Free Unix Group<tfug at tfug.org>
Reply-To: Tucson Free Unix Group <tfug at tfug.org>
Subject: Re: [Tfug] Grub rescue

When I get something like this it seems that what has usually happened
is that, for some reason, the first part of grub can't fine the next
part.

Anything I know to do about it requires a Linux CD or a SuperGrubDisk.

Mostly I have used the Knoppix Hack #83 (in my version), called Repair Grub.

I guess if you get the Knoppix Hack book, hopefully it will be a new
version (mine has Knoppix 3.4 in it) and you can boot from that.

Basically it has you boot from a Linux CD (Ubuntu works great too, for
newer versions I use 8.04 or even 10.04) and boot with that.  Then I
mount the partition that has the /boot/grub subdirectory (the main
Linux partition) for writing.  Then I have had the best luck with this
command ( and I usually just log in as root by using sudo passwd, and
putting in a password for root then su etc):

grub-install --root-directory=/mnt/sdax /dev/sda

If it is hda then change s to h and the x is for the partition.  As
soon as I sudo passwd and then log in a root, I run fdisk -l to see
what the partitions are numbered.  So after I find the partition I
think is the linux boot partition, I mount it for writing and g look
in it to make sure it is the right partition.  For example, I mount
sda5, and look in it and find the usual complement of /
subdirectories, and then examine /boot/grub (or whatever is the
subdirectory for the distro) and look at the grub.conf or menu.lst.
If everything is OK, and say this is sda5, and so dev/sda5 is mounted
on mnt/sda5 (mount it wherever you want), then the command would be:

grub-install --root-directory=/mnt/sda5 /dev/sda

If things go OK, it will make it so you can boot again.  Sometimes it
takes more than that.

Last problem I had like this was 2 days ago when I transferred from an
80 GB IDE to a 250 GB IDE, using PartedMagic4.8, and then before
booting the first time, I installed CentOS5.5, over the Ubuntu,
wanting to use this long term distro with the wireless if possible.

Anyway, after doing that I just got

GRUB>

I grabbed a supergrubdisk and put it in, and used the selection (they
are not very intuitive really) that automatically tries to fix grub,
and it said it would make the Linux the first selection but it
actually just fixed it to what I had it set at, which was windows as
the main boot.  I don't know what it did, but it fixed it.  I don't
know why CentOS didn't fix the MBR/grub situation so it would work in
the first place.

Anybody else have fun with these problems?  IIRC, a version or two ago
Ubuntu was breaking especially with grub 2, during updates.

I am OK with grub2 now, as I have installed StartUpManager, so I can
control the timeout, which system is the default boot, and other
things, again.





On 10/31/10, Charles R. Kiss <charles at kissbrothers.com> wrote:
> Thanks for the tips.  Just to give a little bit more info : I'm not getting
> to the boot menu, after the blinking cursor, the display is:
>
> error: file not found
> grub rescue>
>
> Is there anything I can do with this prompt (input) to get to the old boot
> menu, to start up the Windows boot loader (which is in there somewhere),  or
> even get to kubuntu?
>
> Sent from Samsung mobile
>
> tfug-request at tfug.org wrote:
>

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