TestOut Linux Pro Practice Test 2025 – Complete Exam Prep Guide

To change the GRUB default timeout value, the appropriate file to edit is /etc/default/grub. This file contains the configuration settings that determine how GRUB behaves during boot, including the timeout setting that specifies how long the boot menu is displayed before the default operating system is automatically selected.

When you modify the timeout value in /etc/default/grub, you typically look for the line that starts with `GRUB_TIMEOUT` and set it to the desired number of seconds. After making changes to this file, it is necessary to run the `update-grub` command to apply these changes to the grub configuration, which regenerates /boot/grub/grub.cfg with your updates.

The other options do not serve the purpose of changing the GRUB default timeout value. /boot/grub/grub.cfg is a generated file that is not meant to be edited directly; changes to the GRUB configuration should be made in /etc/default/grub, and then propagated to grub.cfg. /etc/grub.d/default does not exist as a default file in a standard GRUB installation. Lastly, /var/log/grub.log is used for logging purposes and doesn’t control configurations. Thus, the most appropriate file for editing the GRUB default timeout is