mirror of
https://pagure.io/fedora-docs/quick-docs.git
synced 2024-11-24 21:35:17 +00:00
Updated merged GRUB articles for style guidelines
This commit is contained in:
Anthony McGlone
parent
b7fcdc170b
commit
30cb9fa5db
2 changed files with 104 additions and 105 deletions
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@ -22,69 +22,72 @@ bootable by *GRUB2*.
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. Open the terminal.
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. Examine the partition layout and identify the `boot` and the `root` partition.
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. Examine the partition layout and identify the `/boot` and the `/root` partition.
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+
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----
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sudo fdisk -l
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# fdisk -l
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----
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== BTRFS filesystem
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. Follow the <<btrfs-steps, BTRFS steps>> (Fedora 33 or newer) or <<lvm-steps, LVM steps>> (older than Fedora 33) to recover your system.
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If your `root` partition is encrypted by LUKS, it must be decrypted:
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[[btrfs-steps]]
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== BTRFS steps
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If your `/root` partition is encrypted by LUKS, it must be decrypted:
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. Make sure the crypt module is in use:
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+
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----
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sudo modprobe dm-crypt
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# modprobe dm-crypt
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----
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. Decrypt the `root` partition:
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. Decrypt the `/root` partition (e.g. `/dev/sda3`):
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+
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----
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sudo cryptsetup luksOpen <root_partition> myvolume
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# cryptsetup luksOpen /dev/sda3 myvolume
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----
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+
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The decrypted device (i.e. `myvolume`) will be accessible under `/dev/mapper/`.
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Mount the `root` partition:
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Mount the `/root` partition:
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* For LUKS:
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+
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----
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mount <decrypted_device> /mnt -o subvol=root
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# mount /dev/mapper/myvolume /mnt -o subvol=root
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----
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* For non-LUKS:
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+
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----
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mount <root_partition> /mnt -o subvol=root
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# mount /dev/sda3 /mnt -o subvol=root
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----
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Mount the `boot` partition:
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Mount the `/boot` partition (e.g. `/dev/sda2)`:
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----
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mount <boot_partition> /mnt/boot
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# mount /dev/sda2 /mnt/boot
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----
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Mount system processes and devices into the `root` filesystem:
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Mount system processes and devices into the `/root` filesystem:
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----
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mount -o bind /dev /mnt/dev
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mount -o bind /proc /mnt/proc
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mount -o bind /sys /mnt/sys
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mount -o bind /run /mnt/run
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# mount -o bind /dev /mnt/dev
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# mount -o bind /proc /mnt/proc
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# mount -o bind /sys /mnt/sys
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# mount -o bind /run /mnt/run
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----
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On UEFI systems, bind the efivars directory and mount the EFI system partition:
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On UEFI systems, bind the `efivars` directory and mount the EFI system partition (e.g. `/dev/sda1`):
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----
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mount -o bind /sys/firmware/efi/efivars /mnt/sys/firmware/efi/efivars
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mount <efi_system_partition> /mnt/boot/efi
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# mount -o bind /sys/firmware/efi/efivars /mnt/sys/firmware/efi/efivars
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# mount /dev/sda1 /mnt/boot/efi
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----
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Change your filesystem to the one mounted under `/mnt/`:
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----
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chroot /mnt/
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# chroot /mnt/
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----
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Re-install GRUB:
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@ -92,109 +95,103 @@ Re-install GRUB:
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* On UEFI systems, several packages are required:
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+
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----
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dnf reinstall shim-* grub2-efi-* grub2-common
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/]# dnf reinstall shim-* grub2-efi-* grub2-common
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----
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* On BIOS systems, specify the disk where GRUB should be installed:
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* On BIOS systems, specify the disk (e.g. `/dev/sda`) where GRUB should be installed:
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+
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----
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grub2-install <disk>
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/]# grub2-install /dev/sda
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----
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Re-generate the GRUB configuration file:
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----
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grub2-mkconfig -o /boot/grub2/grub.cfg
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/]# grub2-mkconfig -o /boot/grub2/grub.cfg
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----
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Sync and exit the chroot:
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----
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sync && exit
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/]# sync && exit
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----
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Reboot the system.
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== LVM filesystem
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[[lvm-steps]]
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== LVM steps
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If your `root` partition is encrypted by LUKS, it must be decrypted:
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If your `/root` partition is encrypted by LUKS, it must be decrypted:
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. Make sure the crypt module is in use:
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+
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----
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sudo modprobe dm-crypt
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# modprobe dm-crypt
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----
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. Decrypt the `root` partition:
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. Decrypt the `/root` partition (e.g. `/dev/sda3`):
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+
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----
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sudo cryptsetup luksOpen <root_partition> myvolume
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# cryptsetup luksOpen /dev/sda3 myvolume
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----
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. Scan the LVM volumes for the volume group corresponding to the `root` partition:
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. Scan the LVM volumes for the volume group corresponding to the `/root` partition:
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+
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----
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sudo vgscan
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# vgscan
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----
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. Activate the volume group:
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. Activate the volume group (e.g. `fedora_localhost-live`):
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+
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----
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sudo vgchange -ay <volume_group>
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# vgchange -ay fedora_localhost-live
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----
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. Find the root volume:
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. Find the logical volume corresponding to `/root`:
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+
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----
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sudo lvs
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# lvs
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----
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+
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The root volume will be accessible under `/dev/`.
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The logical volume will be accessible under `/dev/mapper/`.
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Create a `root` directory under `/mnt`:
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----
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mkdir -p /mnt/root
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# mkdir -p /mnt/root
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----
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Mount the logical volume of the `root` partition:
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* For LUKS, substitute the root volume from above:
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+
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----
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mount <root_volume> /mnt/root
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----
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* For non-LUKS, use `lsblk` to find the `lvm` that corresponds to the `root` partition (the `lvm` should be under `/dev/mapper/`):
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+
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----
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mount <lvm> /mnt/root
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----
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Mount the `boot` partition:
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Mount the logical volume (e.g. `/dev/mapper/fedora_localhost--live-root`) corresponding to the `/root` partition:
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----
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mount <boot_partition> /mnt/root/boot
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# mount /dev/mapper/fedora_localhost--live-root /mnt/root
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----
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Mount system processes and devices into the `root` filesystem:
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Mount the `/boot` partition (e.g. `/dev/sda2`):
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----
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mount -o bind /dev /mnt/root/dev
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mount -o bind /proc /mnt/root/proc
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mount -o bind /sys /mnt/root/sys
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mount -o bind /run /mnt/root/run
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# mount /dev/sda2 /mnt/root/boot
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----
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On UEFI systems, bind the efivars directory and mount the EFI system partition:
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Mount system processes and devices into the `/root` filesystem:
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----
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mount -o bind /sys/firmware/efi/efivars /mnt/root/sys/firmware/efi/efivars
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mount <efi_system_partition> /mnt/root/boot/efi
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# mount -o bind /dev /mnt/root/dev
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# mount -o bind /proc /mnt/root/proc
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# mount -o bind /sys /mnt/root/sys
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# mount -o bind /run /mnt/root/run
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----
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On UEFI systems, bind the `efivars` directory and mount the EFI system partition (e.g. `/dev/sda1`):
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----
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# mount -o bind /sys/firmware/efi/efivars /mnt/root/sys/firmware/efi/efivars
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# mount /dev/sda1 /mnt/root/boot/efi
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----
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Change your filesystem to the one mounted under `/mnt/root`:
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----
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chroot /mnt/root/
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# chroot /mnt/root/
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----
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Re-install GRUB and re-generate the GRUB configuration file:
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@ -202,20 +199,20 @@ Re-install GRUB and re-generate the GRUB configuration file:
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* On UEFI systems, several packages are required:
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+
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----
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dnf reinstall shim-* grub2-efi-* grub2-common
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grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg
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/]# dnf reinstall shim-* grub2-efi-* grub2-common
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/]# grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg
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----
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* On BIOS systems, specify the disk where GRUB should be installed:
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* On BIOS systems, specify the disk (e.g. `/dev/sda`) where GRUB should be installed:
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+
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----
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grub2-install <disk>
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grub2-mkconfig -o /boot/grub2/grub.cfg
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/]# grub2-install /dev/sda
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/]# grub2-mkconfig -o /boot/grub2/grub.cfg
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----
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Sync and exit the chroot:
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----
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sync && exit
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/]# sync && exit
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----
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Reboot the system.
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@ -2,12 +2,14 @@
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[[using-the-grub-2-boot-prompt]]
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If improperly configured, *GRUB2* may fail to load and subsequently drop
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to a boot prompt. To boot into the system, proceed as follows:
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to a boot prompt. To boot into the system, follow the steps below.
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.Procedure
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. List the drives which *GRUB2* sees:
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+
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----
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grub2> ls
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grub> ls
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----
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. Examine the output to understand the partition table of the `/dev/sda` device. The following example shows a DOS partition table with three partitions:
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@ -25,85 +27,94 @@ A GPT partition table of the `/dev/sda` device with four partitions could look l
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. Probe each partition of the drive and locate your `vmlinuz` and `initramfs` files.
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+
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----
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ls (hd0,1)/
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grub> ls (hd0,1)/
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----
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+
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The outcome of the previous command will list the files on `/dev/sda1`. The partition that contains the `/boot` directory is the correct one. There you will search for the full names of the `vmlinuz` and `initramfs` files.
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. Pre-boot procedure for BTRFS filesystems.
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. Follow the <<btrfs-boot-setup, Pre-boot setup for BTRFS>> (Fedora 33 or newer) or the <<lvm-boot-setup, Pre-boot setup for LVM>> (older than Fedora 33) to recover your system.
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. After the pre-boot setup, boot the system.
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+
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----
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grub> boot
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----
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. To restore the bootloader's functionality, regenerate the *GRUB2* configuration file and reinstall the bootloader into the MBR, as described in xref:adding-other-operating-systems-grub2[Adding other operating systems to the *GRUB2* menu].
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[[btrfs-boot-setup]]
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== Pre-boot setup for BTRFS filesystems.
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* On BIOS systems:
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+
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Set *GRUB2* root to your boot partition. If your boot partition is `(hd0,msdos1)`, the command will be:
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Set *GRUB2* root to your `/boot` partition. If your `/boot` partition is `(hd0,msdos1)`, the command will be:
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+
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----
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set root=(hd0,msdos1)
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grub> set root=(hd0,msdos1)
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----
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Next, select the desired kernel. Set the root partition (e.g. `/dev/sda2`):
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Next, select the desired kernel. Set the `/root` partition (e.g. `/dev/sda2`):
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+
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----
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linux /vmlinuz-5.14.10-300.fc35.x86_64 root=/dev/sda2 ro rootflags=subvol=root
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grub> linux /vmlinuz-5.14.10-300.fc35.x86_64 root=/dev/sda2 ro rootflags=subvol=root
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----
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+
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* On UEFI systems:
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+
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Set *GRUB2* root to your EFI system partition. If your EFI partition is `(hd0,gpt1)`, the command will be:
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Set *GRUB2* root to your EFI system partition. If your EFI system partition is `(hd0,gpt1)`, the command will be:
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+
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----
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set root=(hd0,gpt1)
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grub> set root=(hd0,gpt1)
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----
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Next, select the desired kernel. Find the path to `vmlinuz` and set the root partition (e.g. `/dev/sda3`):
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Next, select the desired kernel. Find the path to `vmlinuz` and set the `/root` partition (e.g. `/dev/sda3`):
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+
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----
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linux (hd0,gpt2)/vmlinuz-5.14.10-300.fc35.x86_64 root=/dev/sda3 ro rootflags=subvol=root
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grub> linux (hd0,gpt2)/vmlinuz-5.14.10-300.fc35.x86_64 root=/dev/sda3 ro rootflags=subvol=root
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----
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+
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Select the RAM filesystem that will be loaded:
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+
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----
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initrd (hd0,gpt2)/initramfs-5.14.10-300.fc35.x86_64.img
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grub> initrd (hd0,gpt2)/initramfs-5.14.10-300.fc35.x86_64.img
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----
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+
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. Pre-boot procedure for LVM filesystems.
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+
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[[lvm-boot-setup]]
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== Pre-boot setup for LVM filesystems.
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Load the `xfs` and `lvm` modules if they are not already loaded (check this with `lsmod`):
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+
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----
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insmod xfs
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insmod lvm
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grub> insmod xfs
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grub> insmod lvm
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----
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+
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* On BIOS systems:
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+
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Set *GRUB2* root to your boot partition. If your boot partition is `(hd0,msdos1)`, the command will be:
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Set *GRUB2* root to your `/boot` partition. If your `/boot` partition is `(hd0,msdos1)`, the command will be:
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+
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----
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set root=(hd0,msdos1)
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grub> set root=(hd0,msdos1)
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----
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Next, select the desired kernel. Set `root` to the `lvm` corresponding to the root directory:
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Next, select the desired kernel. Set `root` to the logical volume that corresponds to the `/root` directory:
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+
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----
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linux /vmlinuz-3.0.0-1.fc16.i686 root=/dev/mapper/fedora_localhost--live-root
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grub> linux /vmlinuz-3.0.0-1.fc16.i686 root=/dev/mapper/fedora_localhost--live-root
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----
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+
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Select the RAM filesystem that will be loaded:
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+
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----
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initrd /initramfs-3.0.0-1.fc16.i686.img
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grub> initrd /initramfs-3.0.0-1.fc16.i686.img
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----
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+
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* On UEFI systems:
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+
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Set *GRUB2* root to your EFI system partition. If your EFI partition is `(hd0,gpt1)`, the command will be:
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Set *GRUB2* root to your EFI system partition. If your EFI system partition is `(hd0,gpt1)`, the command will be:
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+
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----
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set root=(hd0,gpt1)
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----
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Next, select the desired kernel. Find the path to `vmlinuz` and set `root` to the `lvm` corresponding to the root directory:
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Next, select the desired kernel. Find the path to `vmlinuz` and set `root` to the logical volume that corresponds to the `/root` directory:
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+
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----
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linux (hd0,gpt2)/vmlinuz-3.0.0-1.fc16.i686 root=/dev/mapper/fedora_localhost--live-root
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@ -114,12 +125,3 @@ Select the RAM filesystem that will be loaded:
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----
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initrd (hd0,gpt2)/initramfs-3.0.0-1.fc16.i686.img
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----
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+
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. Boot with the selected settings.
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+
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----
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grub> boot
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----
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. To restore the bootloader's functionality, regenerate the *GRUB2* configuration file and reinstall the bootloader into the MBR, as described in xref:adding-other-operating-systems-grub2[Adding other operating systems to the *GRUB2* menu].
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Reference in a new issue