- 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
these commands are still available in rescue mode; examples are from a system with one hard drive on /dev/hda, 2nd partition is ext4
- Returns: (hd0,2): Filesystem is ext2.
- Returns: (horizontal list of files)
- https://askubuntu.com/questions/41930/kernel-panic-not-syncing-vfs-unable-to-mount-root-fs-on-unknown-block0-0/48516#48516 - this actually worked when the Repair Disk did not
- https://ubuntuforums.org/showthread.php?t=1706090 "Grub error unknown filesystem"
Overall, though, this seems to be the magic tool for fixing broken grub booting: https://help.ubuntu.com/community/Boot-Repair
- https://help.ubuntu.com/community/RecoveringUbuntuAfterInstallingWindows - looks like it might discuss the manual steps Boot Repair does
Other links that may be useful: