The grub2-mkconfig command generates a new grub.cfg configuration file, and is used to update an existing grub.cfg file. The grub2-mkconfig command combines the configuration file templates in the /etc/grub.d/ directory with the settings in /etc/default/grub to generate the grub.cfg configuration file.
Syntax
The syntax of the grub2-mkconfig command is:
# grub2-mkconfig [-o {file name}]
If you encounter the below error while running the grub2-mkconfig:
grub2-mkconfig: command not found
You may install the below package:
# dnf install grub2-tools-1
Rebuilding Your GRUB Configuration File
Whenever you change your GRUB configuration, you need to rebuild it. Follow the steps outlined below:
1. The command to rebuild your GRUB configuration varies. On Fedora and openSUSE, use this command:
$ sudo grub2-mkconfig -o /boot/grub2/grub.cfg
Some distros, such as Ubuntu, use:
$ sudo grub-mkconfig -o /boot/grub/grub.cfg
2. Ubuntu Linux also has a script that runs grub-mkconfig, update-grub:
$ sudo update-grub