[Nix-dev] Recovering from a failed GRUB update.

[Lluís Batlle i Rossell]

Hi,

you have nixos-install --chroot.

I am not running master - no idea about the grub problem.

Regards,
Lluís.

On Wed, Jul 08, 2015 at 08:20:22AM -0700, roconnor at theorem.ca wrote:
> For some unknown reason my NixOS update on my laptop last night failed to 
> properly install GRUB (even though I claim that GRUB completed 
> sucessfully).  When I rebooted I was met with a simple grub prompt
> 
> grub>
> 
> and no boot menu.
> 
> 
> Here is what I did to recover.
> 
> (1) I booted from a NixOS install media and logged in as root.
> 
> (2) I mounted my hard disk at /mnt:
>      mount /dev/sda /mnt
> 
> (3) I browsed the system profiles to select the one I wanted to reactive:
>      ls -l /mnt/nix/var/nix/profiles/system*
> 
> My lastest generation is system-27-link.  For safety I decided I 
> wanted to active system-26-link.
> 
> (4) Bind dev and friends:  Loosely following the nixos-install script, I 
> ran the following commands:
>      mount --rbind /dev /mnt/dev
>      mount --rbind /proc /mnt/proc
>      mount --rbind /sys /mnt/sys
> 
> (5) I reactivated the system-26-link generation
>      NIXOS_INSTALL_GRUB=1 chroot /mnt /nix/var/nix/profiles/system-26-link/bin/switch-to-configuration boot
> 
> After that I rebooted, and I was fine.
> 
> 
> This is all written from memory, so there may be errors.
> 
> Also, I didn't actually run the command in step (5).  I actually ran
>      chroot /mnt /bin/sh
> and from the shell I ran the switch-to-configuration command.
> 
> 
> Currently, I'm too scared to try to reproduce the GRUB install failure.
> 
> -- 
> Russell O'Connor                                      <http://r6.ca/>
> ``All talk about `theft,''' the general counsel of the American Graphophone
> Company wrote, ``is the merest claptrap, for there exists no property in
> ideas musical, literary or artistic, except as defined by statute.''
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