Where is the GRUB global command configuration located?

The location of the GRUB global command configuration file is indeed in /etc/default/grub. This file contains various settings that determine the default behavior of the GRUB bootloader. Key parameters that can be set in this file include the default boot entry, timeout duration, and various options related to the graphical appearance and behavior of the boot menu.

When modifications are made to this file, they typically require running the update-grub or grub-mkconfig command to apply the changes and regenerate the GRUB configuration file located at /boot/grub/grub.cfg. This process enables the bootloader to utilize the updated parameters defined in the /etc/default/grub file.

The other locations specified in the options either do not pertain to the general GRUB configuration or are not standard locations used for storing GRUB settings. For instance, /boot/grub/grub.cfg is the actual configuration file used by GRUB at boot, but it's generated from the settings found in /etc/default/grub, making the latter the correct choice for global configurations.