Subject: Dual boot. Ubuntu update removes Debian GRUB.

From: "Stefan.schultz19.5.1991" <[email-masked]>
Date: Thu, 01 Sep 2016 14:30:58 -0400

Dual boot. Ubuntu update removes Debian GRUB.

Hello Debian support,

Last week I installed a few updates to Ubuntu 14.04. It installed the updates and then froze whilst installing Ununtu's grub. After the re-boot, Ubuntu was the only choice of O/S. No sign of Debian.

After a few hours I finally got Debian recovery to reinstall the Grub on the MBR of the SSD.

Some notes.

128GB SSD /dev/sda (GRUB finally reinstalled here)

Partions

60GB Ubuntu /dev/sda1
4GB Ubuntu swap /dev/sda8
54GB Debian 'Jessie' /dev/sda7 (unlocked)
6GB Debian swap /dev/sda6 (unlocked)

GRUB

4GB Debian GRUB /dev/sda5 (will not boot from this)
Ubuntu boot loader is installed here too.

Encrypted partitions

54GB Debian 'Jessie' /dev/mapper/sda7_crypt
6GB Debian swap /dev/mapper/sda6_crypt

TWO QUESTIONS.

1/ Can anybody explain why the Ubuntu update deleted/removed the Debian GRUB?

2/ Is there a Debian approved GRUB boot customizer? I can't find one mentioned anywhere.

Is it possible to resolve this? This would be a pain in the butt, if I had to do this at every Ubuntu update!

Thanks for your help.

Stefan

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From: Felix Miata <[email-masked]>
Date: Thu, 1 Sep 2016 15:45:27 -0400

> 1/ Can anybody explain why the Ubuntu update deleted/removed the Debian GRUB?

Last installed wins always. This gets repeated at update time of a previous 
installation, which is what just happened to you.

This has been explained countless times countless places. Whenever any 
subsequent installation is performed, Windows or Linux, the subsequent 
installer will overwrite the MBR with native code - *unless* you take 
affirmative steps to prevent it from doing so. The how and why is somewhat 
complicated, so in simplest terms, the best thing to do is disallow 
installing anything to the MBR. In practical terms you can't do this with 
Windows, so if Windows will be subsequent, then all you can to is take steps 
in advance to minimize the disruption and ease recovery, something easily 
done in about a minute if familiar with the process and planned for.

> 2/ Is there a Debian approved GRUB boot customizer? I can't find one

Booted to Ubuntu, running os-prober ought to find Debian and put it in its 
Grub2 menu. If you want Debian to be the default, first either reconfigure 
the default selection in Ubuntu, or boot Debian to have it reinstall the 
bootloader. On very next boot to Ubuntu, reconfigure Ubuntu to boot from its 
/ partition.

> to do this at every Ubuntu update!

At least one of the of the two installations needs to have its bootloader 
reconfigured to its / partition instead of MBR.
-- 
"The wise are known for their understanding, and pleasant
words are persuasive." Proverbs 16:21 (New Living Translation)

  Team OS/2 ** Reg. Linux User #211409 ** a11y rocks!

Felix Miata  ***  http://fm.no-ip.com/

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From: Brian <[email-masked]>
Date: Thu, 1 Sep 2016 20:39:52 +0100

> Dual boot. Ubuntu update removes Debian GRUB.

Hello Stefan. There is only me in the office at the moment but the Night
Shift should be along later.

> Last week I installed a few updates to Ubuntu 14.04. It installed the
> updates and then froze whilst installing Ununtu's grub. After the
> re-boot, Ubuntu was the only choice of O/S. No sign of Debian.

"No sign of Debian" is not our responsibility; contact Ubuntu about it.

> After a few hours I finally got Debian recovery to reinstall the Grub

Good thinking,
 
> Some notes.

[Snip]
> 1/ Can anybody explain why the Ubuntu update deleted/removed the

Ubuntu installs its own GRUB to the MBR. However, the menu it produces
should show all the other OSs.

You would experience the same if you installed another Debian to another
partition. It installs its own GRUB to the MBR and produces a new menu.
If that menu did not have all the other OSs it would be a bug. We would
then spring into action.

> 2/ Is there a Debian approved GRUB boot customizer? I can't find one

Please say what you mean by "boot customizer".