- note that the target must be a device (e.g. /dev/sdd), not a partition or filesystem (e.g. /dev/sdd1).
- grub-mkconfig creates a new grub.cfg based on what disks and boot options it finds. Run as root and redirect output to the desired file.
- update-grub updates the grub menu
- bootable drives do not need to be mounted in order to be included