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Update To Grub2 Failed


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I had some problems with grub detecting kernels, so I updated grub to grub2. Iv done it meny times successfully, so I decided to install it straight, with out that chaiload option to see if grub2 works.

However now it wount go to grub, shows a bunch of errors, that on each line is a error...

It puts me to terminal. How could I use it to boot to bt4.

That broken grub is installed on external hdd, where is only bt4 installed. I could easily just reinstall bt4, but I would like to learn how to start bt4 from grubs terminal.

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http://blog.chmouel.com/2010/03/08/howto-use-backtrack4-from-hard-disk-with-grub2/ <--google (backtrack 4 from hard disk w/grub2).

More google for lots of grub and grub2 info. http://ubuntuforums.org/showthread.php?t=1195275


I will reinstall grub. next week.

Im using Ubuntu 10.10 as my main OS, so could I just follow those instructions with out that liveCD/DVD part. Or would it affect my laptops GRUB installation.

Reinstalling GRUB 2 from LiveCD

If you cannot boot from GRUB 2 and need to reinstall it, here is the simple method. For more details or for advanced options, refer to the Ubuntu community documentation here: Grub2 - Reinstalling GRUB 2:

* Boot the Ubuntu Live CD (Try without installing).

* From the Desktop, open a terminal - Applications, Accessories, Terminal.

* Determine your normal system partition - `sudo fdisk -l` (That is a lowercase L)

* If you aren't sure, run `df -Th`. Look for the correct disk size and ext3 or ext4 format.

* Mount your normal system partition:


sudo mount /dev/sdXY /mnt

o If you aren't sure if you mounted the correct partition, once it's mounted run "nautilus /mnt" to inspect the partition. If it is the correct partition, you should see the normal Ubuntu folders such as /bin, /boot, /etc, /home, etc

o Example: sudo mount /dev/sda1 /mnt

o Note: The partition to mount is normally the partition on which Ubuntu was installed: sda1, sdb5, etc. If you have a separate /boot partition, use the device on which the /boot partition is located. Grub 2 works best when installed in the MBR of the drive to which BIOS boots. Also remember that you mount the partition (including the number) in this step, but you do not include the partition number when you run the "sudo grub-install" command later.

o Note: GRUB 2 counts the first drive (X) as "0", but the first partition (Y) as "1"

* Only if you have a separate boot partition:



sudo mount /dev/sdXY /mnt/boot

with sdXY being your /boot partition designation.

* Reinstall GRUB 2:


sudo grub-install --root-directory=/mnt /dev/sdX

Do NOT include the partition number.


o Example: sudo grub-install --root-directory=/mnt /dev/sda

o Note: Substitute the device on which Ubuntu was installed - sda, sdb, etc. Do not specify a partition number.

* Unmount the partition *:


sudo umount /mnt

o * Note: If you mounted a separate /boot partition, unmount it first:


sudo umount /mnt/boot

* Reboot.

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