Re: any way to modify grub from windows?

[Patrick J. LoPresti]

David Fallon <address@hidden> writes:

> So, I'm trying to setup an environment where I can remotely control
> dual booting machines, so I can remotely trigger which os
> (windows/linux) a machine boots up in. I'm trying to do this by
> setting the default boot in grub. Of the four possible configs
> (linux -> windows, linux -> linux, windows -> windows, windows ->
> linux), the only one I have problems with is the last one. So, my
> question is this: Is it possible to compile/run grub with the cygwin
> environment installed (or in general, will it compile on windows)?
> Alternatively, anyone have another suggestions? A windows equiv. to
> grub would be great, as well - there seem to be a few programs that
> will write to the MBR, but they all seem to be shareware.  Any help
> would be greatly appreciated....

Here is one way.

You can store menu.lst on a FAT partition.  GRUB can read FAT, and
Windows and Linux will let you write FAT, so you will be able to
modify menu.lst from either OS.  FAT is a horrible filesystem, though,
so you probably want to format most of your Windows world using NTFS
and only create a small FAT partition specifically for GRUB.

GRUB itself can even read from "hidden" partitions, which means you
can hide this FAT partition so that it does not consume a useless
drive letter.  Unfortunately, Windows will not let you mount a hidden
partition, and to recognize a change from hidden to unhidden requires
a reboot (I think).  So you may end up having to reboot twice to get
from Windows to Linux.  The procedure would be something like this:

  (1) If partition is hidden:
      (a) unhide it
      (b) arrange to restart this procedure after reboot
      (c) reboot

  (2) Edit menu.lst (to boot Linux) and reboot.

For step (1a), you will need a Windows tool to unhide the partition.
FreeDOS fdisk might work, although I do not know whether it can
function from a DOS box.

Step (1b) requires patching the registry; do a Google search on
"RunOnce" and "AutoAdminLogon".

Of course, if the extra drive letter does not bother you, or if you
can find a way to access a hidden FAT partition from Windows, you can
avoid all of this complexity.

If only GRUB could read NTFS...

 - Pat