Linux/grub
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- grub-install
- 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
Commmands
rescue mode
these commands are still available in rescue mode; examples are from a system with one hard drive on /dev/hda, 2nd partition is ext4
ls (hd<drive>,<partition>)- Example:
ls (hd0,2)- Returns: (hd0,2): Filesystem is ext2.
- Example:
ls (hd0,2)/boot/grub- Returns: (horizontal list of files)
- Example:
Notes
- 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
- http://community.linuxmint.com/tutorial/view/245
- http://askubuntu.com/questions/420778/i-need-step-by-step-guidence-to-recover-grub
- https://askubuntu.com/questions/142300/how-to-fix-error-unknown-filesystem-grub-rescue
- https://ubuntuforums.org/showthread.php?t=1706090 "Grub error unknown filesystem"
- https://askubuntu.com/questions/5298/grub-help-and-reinstalling-ubuntu
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: