Re: Breaking out of menu on "live disk", repairing grub

[Andrey Borzenkov]

On Mon, Mar 25, 2013 at 12:08 PM, Simon Hobson <address@hidden> wrote:
> This is probably something really simple I've missed, but ...
>
> Sometimes I have to try and repair systems, and often it is "just" a matter 
> of booting it with another grub and then running grub-install on the system 
> so it can repair it's own grub. But, for something like a Debian Live disk, I 
> can't see how to break out of the grub menu and get to specify my own kernel 
> and initrd lines.

Does it use grub at all? What is often used on CD (at least, until
advent of UEFI) is syslinux.

> Also, back in Grub 1 days, I could remember how to install grub just by 
> mounting the filesystem, chrooting to it, and issuing a few grub commands. 
> I've never managed to make this work with 1.99 (as currently installed with 
> Debian). Is there a simple set of commands that will do what worked in grub 1 
> (going form memory here) :
> hd0 = /dev/sda
> root = (hd0,0)
> install (hd0)
>

mkdir /sysroot
mount /dev/your-root-dev /sysroot
mount /dev/your-boot-dev /sysroot/boot
mount --bind /dev /sysroot/dev
mount --bind /sys /sysroot/sys
mount --bind /proc /sysroot/proc
mount --bind /run /sysroot/run (recommended if you are using systemd)
chroot /sysroot
grub-install /dev/your-grub-boot-device (may be grub2-install on some distro)