Installing Grub from LiveCD after some MBR problems.. help

[tsondie21]

Hello.

I decided to install ubuntu on an external hard drive because I do not have much room on my internal laptop hard drive. After installing it to its own partition on the external, I found that I installed grub onto the internal hard drive. I was able to boot into both ubuntu and vista when the external HD was plugged in, but I was unable to boot into vista when the external was not plugged in. I repaired the vista MBR and so now I can boot into vista no problem. The only thing, is that I cannot boot into ubuntu now because I erased grub. Is there any way I can install grub onto the external partition with a LiveCD or is reinstalling my only option.

If reinstalling is my only option, at what point do I choose which HD or partition to install grub into??

Thank you all so much in advance!

[Herman]

There's no need to re-install, all you need to do is boot your Live CD and open a GRUB shell and re-install GRUB to the MBR in the USB drive.
Probably something like:

sudo grub

find /boot/grub/stage1
(you use the answer you get from the above command for the input in the next command)

root (hd1,0)
Where: the results of the second command indicate that (hd1,0) is the correct disk and partition where /boot/grub/stage1 was found.

setup (hd1,0)

setup (hd1)

quit
Then, next time you boot you should be able to press a key such as your F12 key or some other key during boot-up for a list of bootable devices, and choose your USB disk.
If you can't do that, you'll need either a GRUB floppy disk or a GRUB CD to boot your USB with.
You can use Super Grub Disk (http://www.supergrubdisk.org/), or you can make your own, How to make your own personalized GRUB Floppy Disk (http://users.bigpond.net.au/hermanzone/p15.htm#grub_floppy_howto_make). - How to make your own personalized GRUB CD-RW (http://users.bigpond.net.au/hermanzone/p15.htm#HOW_TO_MAKE_A_GRUB_CD).
Or, you can make a How to make a dedicated GRUB partition (http://users.bigpond.net.au/hermanzone/p15.htm#How_to_make_a_separate_Grub_Partition_). in your hard disk, if you do that then you won't need to mess around with other media every time you want to boot Ubuntu.

[tsondie21]

Thank you so much!

[Herman]

Happy Ubuntuing :D