You have added GRUB_TIMEOUT=10 and a kernel argument to /etc/default/grub on a GRUB 2 system. The next boot ignores both. What was missed?
LPIC-1 Exam 101-500, objective 101. System architecture medium
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Treat it as a good draft rather than as settled fact, and read the source below before you rely on it. It is not used in mock exams here — only questions a person has signed for are.
How these questions are written — where each question comes from, what the verification ledger records, and what happens when one is found wrong.
The options
Correct The generated menu was never rebuilt; `grub-mkconfig -o /boot/grub/grub.cfg` (update-grub on Debian) has to run
Correct. /etc/default/grub and the scripts in /etc/grub.d/ are inputs to a generator. Nothing reads them at boot; the boot loader reads only the generated grub.cfg.
Not correct grub-install has to be re-run so the loader picks up the new settings
Wrong. grub-install installs the boot loader image itself, in the MBR gap or on the EFI System Partition. It does not regenerate the menu file, and re-running it changes nothing about GRUB_TIMEOUT.
Not correct grub-set-default has to be run to commit the values
Wrong. grub-set-default only writes the saved default entry into the GRUB environment block, /boot/grub/grubenv. It has no bearing on timeout or kernel arguments.
Not correct The settings belong in /boot/grub/grub.cfg, which should be edited directly
Wrong, and it is the habit the design is meant to break. grub.cfg carries a header saying it is generated, and the next kernel package upgrade regenerates it and discards the hand edits.
Why
GRUB 2 splits configuration into sources and a build product. /etc/default/grub holds the key=value settings and /etc/grub.d/ holds the numbered scripts that emit menu entries; grub-mkconfig combines them and writes /boot/grub/grub.cfg (or /boot/grub2/grub.cfg on Red Hat family systems). update-grub is a thin Debian wrapper for exactly that command. The rule to carry away is that anything durable is configured in the sources and then regenerated, while grub.cfg is disposable.
Where this comes from
- Cited
- manual page grub-mkconfig(8)
Practise this
Reading one question is not practice. The trainer will draw a short set from objective 101 and space the ones you get wrong.
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