How are the scripts in the /etc/grub.

The scripts in the /etc/grub.d directory are used to generate the /boot/grub2/grub.cfg file and are taken as input by the grub2-mkconfig command. The /boot/grub2/grub.cfg file contains the menu entries and settings for the GRUB2 boot loader. The grub2-mkconfig command is used to create or update this file based on the scripts in /etc/grub.d and other configuration files. The scripts in /etc/grub.d are executed in numerical order and can be customized by the user or administrator. References:https://documentation.suse.com/sles/15-SP3/html/SLES-all/sec-grub2-config.html#sec-grub2-config-files