[Bug 1871186] Re: grub-mkconfig prefers /etc/default/grub.d settings

Benjamin Gemmill 1871186 at bugs.launchpad.net
Wed Feb 18 21:13:07 UTC 2026


I ran into this issue when trying to manipulate
GRUB_CMDLINE_LINUX_DEFAULT on an EC2 instance in /etc/default/grub, and
finding that update-grub did nothing.

For my particular case, if 50-cloudimg-settings.cfg handled GRUB_CMDLINE_LINUX_DEFAULT the same way that /etc/grub.d/10_linux did, by passing existing arguments along:
GRUB_CMDLINE_LINUX_DEFAULT="$GRUB_CMDLINE_LINUX_DEFAULT ...more things go here..."

Then update-grub would work as expected.

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https://bugs.launchpad.net/bugs/1871186

Title:
  grub-mkconfig prefers /etc/default/grub.d settings

Status in grub2 package in Ubuntu:
  Confirmed

Bug description:
  Since the fix for bug 901600 was commited, setting in
  /etc/default/grub now can be overiden by /etc/default/grub.d. It helps
  developers to make customized images, but it can really blows up the
  brain to the rest users.

  I've lost an hour trying to understand why grub ignores my
  GRUB_TIMEOUT settings, until I found hostile file 50-cloudimg-
  settings.cfg, that silently overrides my setting. I think such
  behaviour violates simple principle — user settings must have the
  higest precedence.

  I understand that changing this behaviour, may break a lot of code. So
  please at least add BIG RED BANNER to /etc/default/grub with warning:
  before changing something in the file, check all the files in
  /etc/default/grub.d for conflicting settings, because they have higher
  precedence.

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