Difference between revisions of "Linux/grub"
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* {{l/same|grub-install}} | * {{l/same|grub-install}} | ||
** note that the target must be a ''device'' (e.g. /dev/sdd), not a ''partition'' or ''filesystem'' (e.g. /dev/sdd1). | ** note that the target must be a ''device'' (e.g. /dev/sdd), not a ''partition'' or ''filesystem'' (e.g. /dev/sdd1). | ||
| + | * {{l/same|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. | ||
* {{l/same|update-grub}} updates the grub menu | * {{l/same|update-grub}} updates the grub menu | ||
** bootable drives do not need to be mounted in order to be included | ** 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]]'' | ||
| + | * <code>ls (hd{{arg|drive}},{{arg|partition}})</code> | ||
| + | ** Example: <code>ls (hd0,2)</code> | ||
| + | *** Returns: (hd0,2): Filesystem is ext2. | ||
| + | ** Example: <code>ls (hd0,2)/boot/grub</code> | ||
| + | *** Returns: ''(horizontal list of files)'' | ||
==Notes== | ==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://community.linuxmint.com/tutorial/view/245 | ||
* http://askubuntu.com/questions/420778/i-need-step-by-step-guidence-to-recover-grub | * 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: | ||
| + | * https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/installation_guide/s2-grub-whatis-booting-uefi | ||
| + | * https://www.eightforums.com/threads/uefi-doesnt-recognise-my-bootable-usb-device.16780/ | ||
Latest revision as of 20:40, 11 August 2019
- 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: