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I asked a question in ubuntu forum which has not been solved yet: http://ubuntuforums.org/showthread.php?t=2200335&page=2

To recap briefly, I have an external drive that I boot from different systems. When I have downloaded some newer kernels, I have not been able to get grub2 to give me a menu option to boot the newest kernel.

sudo update-grub

seems to do what it is supposed to. I see a reference to every install on both the internal drive (sda) and the external drive (sdb).

When I run

$ sudo grub-install /dev/sdb

The output I get is:

source_dir doesn't exist. Please specify --target or --directory

I don't want to simply grub-install on /dev/sda, I want to update the grub on the external drive so that I can boot from other systems -- into the newest kernel.

Surely this is easy to do when one knows how. I don't know why it will not work with the two commands shown above though.

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Your answer is here: howtoubuntu.org/… –  Elder Geek Jun 15 '14 at 18:28

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