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Un utile procedura per reinstallare grub su hdd con VLO.
Tratta da: http://ninjix.blogspot.com/2010/07/grubputs-not-found.html
Two of our Ubuntu 10.4 Lucid workstations ran into Grub2 errors today. Something must have gone wrong with the grub2 apt scripts while they were updating to the latest kernel. Both of the machines with the problem were created from the same Clonezilla image but a few of the other cloned machines weren't affected.
After running the apt-get dist-upgrade command and rebooting, my users encountered the "fix symbol 'grub_puts' not found" error.
Instructions
Burn the Ubuntu desktop ISO to CDROM or use the System > Administrator > Startup Disk Creator to create a bootable USB stick.
Boot from your live disk.
Open a terminal and get a list of the available partitions.
sudo fdisk -l
You should see results that look something like this:
Disk /dev/sda: 80.0 GB, 80026361856 bytes
255 heads, 63 sectors/track, 9729 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000e0719
Device Boot Start End Blocks Id System
/dev/sda1 * 1 32 248832 83 Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2 32 9730 77899777 5 Extended
/dev/sda5 32 9730 77899776 83 Linux
Disk /dev/sdb: 8053 MB, 8053063680 bytes
255 heads, 63 sectors/track, 979 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x00009233
Device Boot Start End Blocks Id System
/dev/sdb1 * 1 255 2048256 b W95 FAT32
/dev/sdb2 256 979 5815530 b W95 FAT32
In my example above, you can see the system drive is listed as /dev/sda and the bootable USB is /dev/sdb. You may, like me, have a separate /boot partition because you are running encrypted LVM volumes. In that case you need to pay attention to which is your root volume.
Mount your "root" partition or volume first. Standard Linux partitions are simple.
sudo mount /dev/sda1 /mnt
An encrypted LVM is a little more complicated. The Ubuntu Live CD doesn't have the LVM crypto packages installed so run these commands to get it working.
sudo apt-get install lvm2 cryptsetup
Load the dm-crypt module.
sudo modprobe dm-crypte
Now unlock your encrypted volume. Enter your LUKS passphrase when prompted.
sudo cryptsetup luksOpen /dev/sda2 foo
Load the LVM Kernel module.
sudo modprobe dm-mod
Scan for all of the available volume groups.
sudo vgscan
Active the volume group.
sudo vgchange -a
Now list the logical volumes along with their /dev paths. In the example below, note that my laptop is named "falcon" and yours is most likely something else.
sudo lvscan
ACTIVE '/dev/falcon/root' [71.22 GiB] inherit
ACTIVE '/dev/falcon/swap_1' [3.07 GiB] inherit
Now mount the root volume to /mnt. Replace falcon to match your own results of the previous command.
sudo mount /dev/falcon/root /mnt
Chroot Prep
Now mount the /dev, /proc, /sys folders for os-prober and grub to work properly in a chrooted jail.
sudo mount --bind /dev /mnt/dev
sudo mount --bind /proc /mnt/proc
sudo mount --bind /sys /mnt/sys
If you had separate /boot partition because of LVM then mount it now.
sudo mount /dev/sda1 /mnt/boot
Now chroot yourself.
sudo chroot /mnt
Repair Grub2
Run the grub-mkconfig command to generate a new grub2 configuration file. This might be what got corrupted and left in this lurch.
grub-mkconfig -o /boot/grub/grub.cfg
Make sure no errors were generated. Then install grub2 in the hard drive MBR.
grub-install /dev/sda
Again make sure didn't get any errors. If you want a warm and fuzzy test your repair with the recheck option.
grub-install --recheck /dev/sda
Exit out of chroot with an exit or Crt+D command.
Unmount the directories.
sudo umount /mnt/dev
sudo umount /mnt
Now reboot and you should have your system back.
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