Hosed Grub with the push of a button

[Patrick O'Callaghan]

On Wed, 2008-04-16 at 09:41 -0400, max bianco wrote:
> On Wed, Apr 16, 2008 at 8:30 AM, David Timms <dtimms at iinet.net.au> wrote:
> >
> > max wrote:
> >
> > > I hosed grub. I need to fix it. I booted from fedora rescue. I chroot to
> > /mnt/sysimage. All good. I tried :
> > >
> > > grub-install  /dev/sda
> > >
> > > The  file /boot/grub/stage1 not read correctly
> > >
> > > tried:
> > >
> > > grub-install /dev/VolGroup00/LogVol00
> > >
> > > The file /boot/grub/stage1 not read correctly
> > >
> > >
> > > tried:
> > >
> > > cd /boot/grub
> > >
> > > cat stage1
> > >
> > > output maybe human readable by some humans but not this one.
> > >
> > > So far I can still see all the user files so I can backup and reinstall
> > but that wouldn't teach me anything.
> > > All suggestions/insults/how-to's welcome.
> > >
> >  How about using the grub bits that are on the rescue media, rather than on
> > the hosed disk ?
> >
> >  ie exit from the chroot, and then grub-install wherever ?
> >  {Or my memory might have faded ?}
> >
> >  DaveT.
> >
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> >
> I'm willing to try it but i'm not really sure what your suggesting.If
> i exit from the chroot and grub-install how will it write to the
> appropriate place? At this point all the user data is recoverable and
> i'd like to keep it that way but if in the course of learning I hose
> that too, well i'm willing to take the chance but i'd like to avoid it
> if possible.

AFAIK grub-install by default will write to the MBR of the first hard
disk. It doesn't depend on where your root is (which is a filesystem
construct). Also, it won't touch the partition table so your user data
should still be recoverable in the worst case.

Back it up first just in case ...

poc