reinstallinggrub

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Why?

Grub has failed to install, upgrade, or be configured properly to the point the system cannot boot. The grub recovery console is not available in times like this.

How?

To boot strap yourself into grub, the best way is to chroot the system from a fully working system. A live USB/CD image would do this, as well as simply pulling the drive and mounting it on ones workstation. Once you have access to a working system, this is the proccedure:

In this setup we will assume the following:

You are booting off a USB image, /dev/sda.
Your target system (broken grub) is /dev/sdb.
/dev/sdb1 is /boot
/dev/sdb2 is /

Mount the target

Mount the target system, in this example we will use /mnt
```
  mount /dev/sdb2 /mnt
```
Next, mount the /boot partition into the `/mnt' target.
```
  mount /dev/sdb1 /mnt/boot
```

Bind mount your system to the target

We wil have to bind mount /dev, /sys, and /proc into the target /mnt' system so that we can trickgrub-install' into thinking our system is really running:
```
  mount -o bind /dev /mnt/dev
  mount -o bind /proc /mnt/proc
  mount -o bind /sys /mnt/sys
```

Chroot to the target, and install grub.

Now we can do what we came here for, chroot and install grub. First, chroot:
```
  chroot /mnt
```
If the above command worked, you can now install grub to the target disk, /dev/sdb:
```
  grub-install /dev/sdb
```

Exit the chroot, and cleanup

Exit the chroot:
```
  exit
```

Remove all the bind mounts, then unmount the partitions:

  umount /mnt/sys
  umount /mnt/proc
  umount /mnt/dev
  umount /mnt/boot
  umount /mnt