Need Help Editing Grub
Mark Phillips
mark at phillipsmarketing.biz
Sun Jan 24 19:49:06 MST 2010
I found a helpful post at http://ubuntuforums.org/showthread.php?t=159346.
The best part is:
3.Type "grub" ,which makes a grumb prompt appear.
4.Type "find /boot/grub/stage1. youll get an response like "(hd0)" or in my
case (hd0,3),use whatever your computer spitts out for the next lines.
5.Type "root (hd0,3).
6.Type "setup (hd0,3)", *other instructions says to use "(hd0) ,and thats
fine if u want to write GRUB to the mbr. if you want to write it to your
linux root partition, then you want the number after the comma,such as
"(hd0,3).*
In my case, /boot/grub/stage1 is at (hd1,4), so i guess I need to try
grub
root (hd1,4)
setup (hd1)
quit.
Sound right?
Mark
On Sun, Jan 24, 2010 at 7:34 PM, Mark Phillips
<mark at phillipsmarketing.biz>wrote:
> Eric,
>
> Maybe this is what KP was trying to say
> grub
> root (hd1,0)
> setup(hd1)
> quit
>
> Because, when I boot the system now, hd1 is my Linux drive. So I have to
> setup grub on my Linux drive while it is running. Then I switch the Linux
> drive to the first ide channel, so it becomes the first mbr to be read, and
> it has grub installed there. I believe the current configuration has the mbr
> on the first ide drive (windows) point to the mbr on the second ide drive
> (linux and grub). I have to break that chain so the mbr of the second ide
> drive is now the boot mbr.
>
> The alternative would be to switch drives now, boot with a rescue disk and
> perform
> grub
> root (hd0,0)
> setup (hd0)
> quit
>
> Does this make sense?
>
> Mark
>
>
> On Sun, Jan 24, 2010 at 7:18 PM, Eric Shubert <ejs at shubes.net> wrote:
>
>>
>> Mark,
>> I don't understand entirely the commands that kitepilot said to use
>> either.
>>
>> Your menu.lst file looks correct.
>>
>> savedefault, along with the "default" setting listed earlier in
>> menu.lst, controls which kernel is used as the default. savedefault
>> means "use me to boot next time", so generally speaking, the computer
>> boots whichever OS was running last. Providing the "default" setting
>> corresponds to this behavior.
>>
>> makeactive and chainloader commands are used with windows partitions.
>> makeactive makes the partition active (whatever that means, but windows
>> seems to require it), and chainloader, which effectively passes control
>> over to the windows loader program, not unlike what happens when the
>> bios passes control to grub. At least that's what I would guess.
>>
>> If grub is not installed in the mbr of the 2nd drive, it needs to be. I
>> think that might be what kp was trying to get to. In order to install
>> grub on mbr of drive hda, issue the "grub" command at the cli. Then at
>> the grub prompt, enter the part after the prompt:
>> grub> root (hd0,0)
>> grub> setup (hd0)
>> grub> quit
>>
>> If your OS is the 2nd partition on the drive, then you'd specify:
>> grub> root (hd0,1)
>>
>> If your drive is hdb, then you'd use hd1 in place of hd0.
>>
>> That drive would then run grub when it's booted.
>>
>> --
>> -Eric 'shubes'
>>
>>
>> Mark Phillips wrote:
>> > This is what I have in menu.lst
>> >
>> > title Debian GNU/Linux, kernel 2.6.26-2-686
>> > root (hd1,4)
>> > kernel /boot/vmlinuz-2.6.26-2-686 root=/dev/hdb5 ro
>> > initrd /boot/initrd.img-2.6.26-2-686
>> >
>> > title Microsoft Windows XP Professional
>> > root (hd0,0)
>> > savedefault
>> > makeactive
>> > chainloader +1
>> >
>> > So, I change
>> > title Debian GNU/Linux, kernel 2.6.26-2-686
>> > root (hd1,4)
>> > kernel /boot/vmlinuz-2.6.26-2-686 root=/dev/hdb5 ro
>> > initrd /boot/initrd.img-2.6.26-2-686
>> >
>> > to
>> >
>> > title Debian GNU/Linux, kernel 2.6.26-2-686
>> > root (hd0,4) <-- change1 to 0 here
>> > kernel /boot/vmlinuz-2.6.26-2-686 root=/dev/hda5 ro <--- change
>> > b to a here
>> > initrd /boot/initrd.img-2.6.26-2-686
>> >
>> > and remove
>> > title Microsoft Windows XP Professional
>> > root (hd0,0)
>> >
>> > What about these bad boys.....
>> > savedefault
>> > makeactive
>> > chainloader +1
>> >
>> > I still don't understand the grub commands that I was told to use.
>> >
>> > Mark
>> >
>> > On Sun, Jan 24, 2010 at 5:58 PM, Eric Shubert <ejs at shubes.net
>> > <mailto:ejs at shubes.net>> wrote:
>> >
>> > "every reference to hd1,0 is converted to hd0,0"
>> > You need to edit this manually. hd1 in grub corresponds to hdb in
>> linux,
>> > and hd0 in grub is hda in linux.
>> >
>> > Mark Phillips wrote:
>> > > I understand the flow....shouldn't I tell grub somehow that the
>> > new boot
>> > > drive is hd0,0? In your steps below, is there perhaps, a typo?
>> > >
>> > > Thanks!
>> > >
>> > > Mark
>> > >
>> > > On Sun, Jan 24, 2010 at 3:58 PM, kitepilot at kitepilot.com
>> > <mailto:kitepilot at kitepilot.com>
>> > > <mailto:kitepilot at kitepilot.com <mailto:kitepilot at kitepilot.com
>> >>
>> > <kitepilot at kitepilot.com <mailto:kitepilot at kitepilot.com>
>> > > <mailto:kitepilot at kitepilot.com
>> > <mailto:kitepilot at kitepilot.com>>> wrote:
>> > >
>> > > >> 1. How do I change grub on the Linux drive (hdb) to say
>> > "the ...
>> > > If you are running GRUB 0.XX (GRUB 1.XX is different):
>> > > Boot your Debian machine and as root run:
>> > > grub
>> > > root (hd1,0)
>> > > root (hd1)
>> > > It should answer that it found the stages, verify that there
>> > are no
>> > > errors.
>> > > quit
>> > >
>> > >
>> > > Then take a backup of /boot/grub/menu.lst and and make sure
>> that
>> > > everything
>> > > is either using UUID(s) or labels or every reference to hd1,0
>> is
>> > > converted
>> > > to hd0,0
>> > >
>> > > Verify your /etc/fstab likewise.
>> > >
>> > >
>> > > > 2. Do I move the second drive to the first ide port, or
>> > leave it
>> > > as ...
>> > > Shutdown, pull the cable from the windoze drive and plug it
>> > to Linux
>> > > drive.
>> > > Turn on and pray... :)
>> > > Free advice, you can't sue me ;-)
>> > > YMMV
>> > > ET
>> > >
>> > >
>> > >
>> > >
>> > > Mark Phillips writes:
>> > >
>> > > > I have two ide drives in one machine - drive 1 is a
>> > Windows drive
>> > > and drive
>> > > > 2 is a Linux drive. Using grub, I can boot into either
>> > windows or
>> > > debian. I
>> > > > want to remove the windows drive and replace it with a
>> larger,
>> > > blank drive
>> > > > for backup storage. I have a feeling if I just remove the
>> > first
>> > > drive and
>> > > > put the new one there, the machine will not boot, since
>> > the MBR
>> > > is probably
>> > > > on the first drive (it came with the machine, and I just
>> added
>> > > the second
>> > > > drive for Linux). My questions:
>> > > >
>> > > > 1. How do I change grub on the Linux drive (hdb) to say
>> "the
>> > > windows drive
>> > > > is dead, boot here instead, long live linux"?
>> > > >
>> > > > 2. Do I move the second drive to the first ide port, or
>> > leave it
>> > > as the
>> > > > second ide drive and put the new drive in the fist ide
>> port?
>> > > >
>> > > > Thanks!
>> > > >
>> > > > Mark
>> > > ---------------------------------------------------
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>> > >
>>
>>
>> --
>> -Eric 'shubes'
>>
>> ---------------------------------------------------
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>
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