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I installed Windows 8 Consumer Preview, and Windows replaced the boot manager (GRUB). Usually, I could restore GRUB using Super Grub Disk, but in this case I had to use Rescatux, because SGD returned errors.

Now, I can run Ubuntu and Debian, but not Windows. GRUB doesn't seem to recognize the Windows installation as operating system. I tried update-grub and os-prober. How can I make Windows visible for GRUB?

Boot Info Script returns this

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Your title says GRUB2, but your body and tags say GRUB. Are you using GRUB2 or GRUB? – Raystafarian Mar 4 '12 at 0:38

Just add a Windows entry like you would normally do.

Yes, this requires some fiddling. I guess you open up a random example and copy the Windows part of it into your own menu.lst usually located in /boot or /boot/grub or somewhere around there. Then the only thing left to do is finding the right root to boot from.

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I'm guessing you have GRUB2. If that's so, you can't add Windows to a menu.lst anymore. It's slightly more complex. You'll need to create a script for the menu entry in /etc/grub.d/:

sudo nano /etc/default/grub.d/50_windows

Then you'll need to create a simple script that will allow you to boot from the appropriate partition. As far as the script itself, it should look something like this:

#!/bin/sh -e
cat << EOF
menuentry "Windows 8 Consumer Preview" {
set root=(hd0,1)
chainloader (hd0,1)+1
}
EOF

But I'm not sure exactly, and it will of course depend on your boot setup, especially which drive/partition holds your Windows install. Remember that GRUB2 lists partitions starting with 1, not 0 like GRUB legacy did. That means hda1 will be (hd0,1) and NOT (hd0,0). Next you need to mark it as executable so that grub can use it:

sudo chmod 755 /etc/grub.d/50_windows

Then update GRUB so that it can find your new entry:

sudo update-grub

With any luck, you should now have a working Windows entry, but remember my example script will almost definitely not work for you, it will have to be modified for your install!

P. S. This tutorial may seem a little dumbed-down to the OP, who obviously seems to have decent technical knowledge. No disrespect; I was trying to be understandable to any noobs that may find this page later.

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The OP is indeed using GRUB2, see the Pastebin link at the end of the question. – bwDraco May 6 '12 at 1:37

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