Subj : Updating grub boot order w/out update-grub?
To   : Dumas Walker
From : Arelor
Date : Mon Sep 23 2019 05:28 am

  Re: Updating grub boot order w/out update-grub?
  By: Dumas Walker to All on Sun Sep 22 2019 02:22 pm

 >
 > So is there a way to get the grub on the sd card updated from another
 > machine so that the sbc will boot again?  I am thinking maybe I can rename
 > the vmlinuz and initrd images in the /boot directory (to back them up) for
 > the version that won't boot, and then create symlinks named after them that
 > point to the old versions instead.  That is the only think I have come up
 > with so far but have not tried it yet.  :(
 >

My suggestion:

insert the card or storage media of the sbc into
a running system with a matching architecture,
mount that card and chroot to it. ie:

# mount /dev/your_card /mnt/whatever
# mount -o bind,dev /dev /mnt/whatever/dev
# mount -o bind,proc /proc /mnt/whatever/proc
# mount -o bind,sys /sys /mnt/whatever/sys
# chroot /mnt/whatever sh

Now you are inside the operating system of the
card. Configure the bootloader to your leissure
.. You may also want to give other boot loaders
a try, such as Lilo or Syslinux, which imo are
way more sane for small simple setups.

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