how to restore or recover the boot-loader after installing Windows. Ubuntu uses the Grub boot-loader; refer to the GrubHowto or Grub2 for more information on Grub. Some reasons to repair your boot-loader might include installing Microsoft Windows after you have installed Ubuntu, adding or removing a hard drive, or changing hard drive settings.
Note: These instructions provide multiple options. Pick the option which works best for you; otherwise, choose recommended option.
Recovery Using the Ubuntu Desktop/Live CD (RECOMMENDED)
Introduction
This method will install Grub boot-loader into the Master Boot Record (MBR) of the main computer hard drive.
The slight complexity of this method consists of determining whether Ubuntu Operating System installed on your computer was configured for Grub or Grub 2.
If you fresh-installed Ubuntu Karmic 9.10 or newer, you are running Grub2.
If you ran previous version of Ubuntu and upgraded to Ubuntu Karmic 9.10, you are running Grub Legacy by default; unless you have executed upgrade-from-grub-legacy, then you are running Grub2.
If you are running Ubuntu Jaunty or Intrepid, you are running Grub Legacy.
If you are not sure, follow the guide assuming you are running Grub2 -- there will be a point to make a correction.
You can check the current version installed on your system via Synaptic or from the command line. Open a Terminal and enter the following:
grub-install -v
GRUB 2 should display a version number of 1.96 or later. Legacy GRUB is version 0.97.
Grub2: Download the latest version of Ubuntu Desktop edition from http://www.ubuntu.com/GetUbuntu/download and burn your Ubuntu CD.
Grub Legacy: See the dual-boot guide about recovering grub
Reboot your computer and boot into a live session.
Mount your Ubuntu partition from Places menu. If you have multiple Ubuntu partitions (e.g., /boot, /home, /), you need to mount the /boot partition.
Are you using Grub or Grub 2?
Skip this section if you are sure about your version of Grub
Go into boot/grub directory and check for the existence of the files menu.lst and grub.cfg.
Grub Legacy uses boot/grub/menu.lst.
Grub 2 uses uses boot/grub/grub.cfg.
If you are still not sure, view the file and check whether syntax follows Grub2 conventions.
If you downloaded Ubuntu Karmic 9.10 Live CD, but your installed version of Ubuntu uses Grub Legacy, please use this guide
https://help.ubuntu.com/community/DualBoot/Grub#Ubuntu%209.10%20&%20earlier
Verify if your partition is correct.
mount | tail -1
You should see output similar to this:
/dev/sda2 on /media/0d104aff-ec8c-44c8-b811-92b993823444 type ext4 (rw,nosuid,nodev,uhelper=devkit)
Note the designation for the disk /dev/sda which you will be using later, and the directory in /media.
Use Tab Completion in Terminal to complete the path. Hitting the
To make sure this is indeed the Ubuntu boot partition, run
ls /media/0d104aff-ec8c-44c8-b811-92b993823444/boot
But substitute the example's UUID, 0d104aff-ec8c-44c8-b811-92b993823444, with your volume's UUID which you found earlier. If your boot partition was a separate partition which you mounted in a previous step, use this instead
ls /media/0d104aff-ec8c-44c8-b811-92b993823444
In either case, the output should be something like this:
config-2.6.18-3-686 initrd.img-2.6.18-3-686.bak System.map-2.6.18-3-686
grub lost+found vmlinuz-2.6.18-3-686
initrd.img-2.6.18-3-686 memtest86+.bin
If what you have is not similar, unmount it and try another partition.
Now that everything is mounted, we just need to reinstall GRUB by specifying the correct directory and the correct drive name:
sudo grub-install --root-directory=/media/0d104aff-ec8c-44c8-b811-92b993823444 /dev/sda
If you get BIOS warnings try:
sudo grub-install --root-directory=/media/0d104aff-ec8c-44c8-b811-92b993823444 /dev/sda --recheck
Replace /dev/sda with the location you want to install GRUB on.
If all went well, you should see something like this:
Installation finished. No error reported.
This is the contents of the device map /boot/grub/device.map.
Check if this is correct or not. If any of the lines is incorrect,
fix it and re-run the script `grub-install'.
(hd0) /dev/sda
Reboot, making sure to boot to your hard drive and not to the live CD. Grub should be installed and both Ubuntu and Windows should have been automatically detected and listed in the menu.
The Master Boot Record will execute Grub as the initial boot-loader. The Windows boot-loader is contained within the Windows partition and will then be chainloaded by the Grub boot-loader.
For Grub Legacy
Please refer to the guide
https://help.ubuntu.com/community/DualBoot/Grub#Ubuntu%209.10%20&%20earlier
Troubleshooting
I don't see a Grub menu
If the menu is not normally displayed during boot, hold down the SHIFT key as the computer attempts to boot to display the GRUB 2 menu. For Grub Legacy, use ESC key to display a menu.
Grub comes up in shell mode with no boot menu
You may have mixed up Grub Legacy and Grub 2. This symptom is most typical when you assumed you have Grub 2, but your Ubuntu OS actually uses Grub Legacy. Follow these instructions again using Ubuntu 9.04 Live CD.
If you are certain you have Grub 2 and it's still displaying shell mode by now, follow the method using chroot listed here... http://www.ubuntu-inside.me/2009/06/howto-recover-grub2-after-windows.html.
What if Grub 2 does not list Windows
If, after installing grub, Windows does not appear in the boot-menu, boot into Ubuntu and execute command
sudo update-grub2
Grub 2 gives "error: no such device: xxxxx.xxxxx.xxxxx.xxxx"
If at any time grub2 gives this error, boot up into Ubuntu (on hard disk if possible, otherwise with Live CD), open a terminal and run command
sudo update-grub2
This should automatically detect the devices and configure grub appropriately.
What if Grub Legacy misses Windows
If, after installing grub, Windows does not appear in the boot menu, you will need to edit /boot/grub/menu.lst (That is a lowercase "L" and not the number 1 in menu.lst)
Open a terminal and enter:
gksu gedit /boot/grub/menu.lst
Or, in Kubuntu:
kdesu kate /boot/grub/menu.lst
Your Windows stanza should look something like this:
title Windows XP/Vista # Use any title you wish, it will appear in the grub boot menu
rootnoverify (hd0,0) # This is the location of the windows partition
makeactive
chainloader +1
Note: Put your Windows stanza before or after AUTOMAGIC KERNEL LIST in the menu.lst
Recovery using Microsoft Windows and Its Bootloader
If you have your Linux system in a second (or third...) hard disk this method will not work. Please check Super Grub Disk's method that address this problem.
This method will also fail with Grub 2.
This method allows you to restore GRUB and keep the Windows boot-loader as your primary boot-loader. Thanks to Ubuntu's support for NTFS writing this method is now quite simple.
The previous method puts GRUB back on the MBR (Master Boot Record) of the hard drive instead of in the root partition. Should you not wish to do so, for instance if you use a third-party boot manager like Boot Magic or System Commander, this next suggestion will be helpful. Another reason to prefer this method is for when restoring the Grub menu after a re-ghosting. In either case, use this alternative.
Restoring GRUB
1. Boot from a Live CD, like Ubuntu Desktop, or similar. It is recommended to use Ubuntu 9.04 or newer as this has NTFS write support.
2. Open a Terminal. Open a root terminal (For non-Ubuntu live CDs type su the terminal. For Ubuntu based distros run
sudo -i
Enter root passwords as necessary.
3. Type
grub
which makes a GRUB prompt appear.
4. Type
find /boot/grub/stage1
You'll get a response like "(hd0)" or in my case "(hd0,3)". Use the output from this command for the following commands.
Note:
You should have mounted the partition which has your Linux system before typing this command. (e.g. In Knoppix Live CD partitions are shown on the desktop but they're not mounted until you double-click on them or mount them manually)
5. Type
root (hd0,3)
note the space between root and (hd0,3).
6. Type
setup (hd0,3)
into the prompt. This is key. Other instructions say to use "(hd0)", and that's fine if you 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)".
7. Type
quit
8. At this stage you can either restart the system and install your own boot-loader, or you can continue and tell the Windows boot-loader where to find GRUB which will handle booting Linux.
Making Windows Load GRUB (and then Linux)
This is taken from Dual-Boot Linux and Windows 2000/Windows XP with GRUB HOWTO which has been helping people dual boot since at least 2005.
1. In Linux open a command window.
2. Mount a drive which you can share with Windows. This could be a USB drive, a FAT32 partition on your hard drive, or if you are using a Linux distribution which supports NTFS writing natively (Such as Ubuntu 8.04 or later) then you can mount the actual Windows C:\ drive itself! The advantage of writing to the Windows drive is that you are going to need to put a file there eventually, so it saves time copying a file around. For example:
#mkdir /tmp/windows
#mount /dev/sda1 /tmp/windows
However, when writing directly to the C:\ drive you could also do some damage to the system if you delete or move something. If you do pick the option to write directly, go in, put the file where it belongs, and touch NOTHING else.
3. Now you are going to make a copy of your boot partition. Finding out what this is called is not always completely reliable since the Linux naming conventions differ from the GRUB naming conventions. Linux labels partitions as hd[Letter][Number] or sd[Letter][Number] whereas GRUB always names them as hd[Number][Number]. If you installed GRUB on (hd0,0), then the /boot partition will be on hda1 or sda1. (Since (hd1,0) == hdb1 or sdb1, then by extension if you installed GRUB on (hd0,1) then the /boot partition will be on hda2 or sda2 and so on and so forth.) This narrows you down to two possibilities. If you now paste
ls /dev |grep hd
it will let you know if you have that drive on your machine. If nothing comes up which matches, then that means you must have an sd drive.
Note: The command df won't work as you are booted from a Live CD.
4. Having determined your boot partition run this command as root by using sudo
sudo #dd if=/dev/sda2 of=/tmp/windows/linux.bin bs=512 count=1
Looking at this example /dev/sda2 is your boot partition and /tmp/windows/ is the drive you want to copy the boot sector image to.
5. If you haven't created linux.bin in the Windows drive then you need to copy it there now.
6. Next, reboot your computer and boot into Windows. Open C:\boot.ini in Notepad, and add a new line at the bottom:
c:\linux.bin="Linux"
This file might be write protected. If that is so, you need to enable writing to the file. To do so, right click, and from the context menu select Properties. Then uncheck the box that says "File is read only". Make sure to put that checkmark back afterwards.
Next, make sure that at the top of the boot.ini file there is a timeout set, i.e timeout=5 or some such number.
Do not edit this file from the Live CD, even if you have NTFS write support. Linux and Windows represent line breaks in different ways, so even though you can edit the file, it won't add a new line.
7. That's it, reboot and you will be given the option of booting into Linux, selecting that will chainload GRUB and this will let you boot into your Linux distro.
Source: http://ubuntuforums.org/showpost.php?p=121355&postcount=5
Recovery Using the Unofficial Rescatux
Note about grub2: Rescatux can be used to restore either Grub (Ubuntu 9.04 and previous versions) or Grub2 (Ubuntu 9.10 and later versions)
Download Rescatux
Burn the Rescatux ISO in a cdrom
Make your PC boot from the cdrom
At Debian Live Boot screen just press ENTER
Select Restore grub / Fix Linux Boot option and click on OK button
Select the partition where your Ubuntu is and click on OK button
Select the hard disk where you want Grub to be installed (usually the first one)
Grub was installed OK confirmation / Grub was not installed error will appear
Look for System -> Shutdown in the top tray in order to halt your machine
Recovery Using the Unofficial "Super Grub Disk"
Note about grub2: The methods regarding "Super Grub Disk" described here do not work with grub2 but with grub legacy. That means that you should not use them for fresh Ubuntu 9.10 install or Ubuntu newer versions.
From within Windows
Download Auto Super Grub Disk
Double-click auto_super_grub_disk_1.7 icon, install it, and reboot.
On the next boot, select the UNetbootin-supergrubdisk menu entry; this will launch the Auto Super Grub Disk.
Do nothing till you see your Grub menu again.
Next time you boot Windows, click yes when asked to remove UNetbootin-supergrubdisk to remove the Super Grub Disk menu entry.
As a standalone cd/floppy/usb
Download Super Grub Disk
Burn into a cdrom (better) or a floppy
Boot from it
Select: GRUB => MBR & !LINUX! (>2) MANUAL |8-)
Select the Linux or Grub installation you want to restore.
You see the message: SGD has done it!
Reboot
You're done.
Preserving Windows Bootloader
The method shown above puts GRUB back on the MBR (Master Boot Record) of the hard drive instead of in the root partition. If you use a third-party boot manager like Boot Magic or System Commander you probably won't want to do that. This method could also be used to restore the Grub menu after a re-ghosting. If this is the case, use this alternative.
NOTE: This alternative, used without a third-party boot manager, will not cause Ubuntu to boot.
This method will let you boot your second hard disk Linux installations from Windows while the Using the Ubuntu Desktop/Live CD. Preserving Windows Boot-loader instructions will not.
Either:
Download Super Grub Disk
Burn into a cdrom (suggested) or a floppy
Boot from it
Or:
Download UNetbootin Super Grub Disk Loader (Windows .exe version)
Run the installer and reboot when once done installing.
On the next boot, select the "UNetbootin-supergrubdisk" menu entry; this will launch the Super Grub Disk interface.
Then:
Pick the Super Grub Disk (WITH HELP) :-))) option
Select your language from the list
Choose Windows
Select: Windows chainloads Grub!
Select the Linux or Grub installation you want to restore to its own partition.
You see the message: SGD has done it!
Reboot
Job completed.
Recovery Using the Ubuntu Alternate/Install CD
This section explains how to rescue Grub, using the Ubuntu Alternate/install CD.
Enter your computers BIOS to check computer can boot from CD ROM. If you can boot from CD, insert CD ROM into drive. Exit the BIOS (if needed save your settings to make sure the computer boots from the CD ROM).
When the Ubuntu splash screen comes up with the boot: prompt, type in rescue and press enter.
Choose your language, location (country) and then keyboard layout as if you were doing a fresh install.
Enter a host name, or leave it with the default (Ubuntu).
At this stage you are presented with a screen where you can select which partition is your root partition (there is a list of the partitions on your hard drive, so you are required to know which partition number Ubuntu is on). This will be dev/discs/disc0/partX, where the X is a partition number.
you are then presented with a command prompt (a hash).
type
$ grub-install /dev/XXX
where XXX is the device of your Ubuntu install. (eg: grub-install /dev/""hda"" or grub-install /dev/""sdb"" ). Note: newer 2.6.xx kernels call all hard disks ""sdx"" now but not sure if grub does.
The GUI Way: Using the Alternate/Install CD and Overwriting the Windows bootloader
Again, this is for Grub legacy, not for Grub2. So, do not try with Ubuntu 10.04 or more recent unless you have deliberately installed Grub legacy and managed to get it working in the past.
After re-initializing your mount points and other options, and after writing the changes to disk, system files are automatically installed. Each time I have tried this an error is thrown that busybox-initramfs could not be installed (I assume because a newer version exists - but I don't know. This error MIGHT be avoided if one has internet access, again, I don't know). The error aborts the installation of system files, and returns you to the menu. If you then select to install the grub boot-loader, it too, errors-out because the installation of system files did not complete. You are stuck in a loop. Unless you know some bash-magic to bypass this impasse, your only alternative (you will be unable to boot into your system now), is to return to the partitioner, reformat, and reinstall from scratch.
Boot your computer with the Ubuntu CD
Go through the installation process until you reach "[!!!] Disk Partition"
Select Manual Partition
Mount your appropriate linux partitions:
/
/boot
swap
...
DO NOT FORMAT THEM.
Finish the manual partition
Say "Yes" when it asks you to save the changes
It will give you errors saying that "the system couldn't install ....." after that
Ignore them, keep select "continue" until you get back to the Ubuntu installation menu
Jump to "Install Grub ...."
Once it is finished, just restart your computer
From: http://doc.gwos.org/index.php/Restore_Grub and http://ubuntuforums.org/showthread.php?t=76652
Recovery Using Third-Party Proprietary Software
This software runs only under Microsoft Windows.
EasyBCD software allows Microsoft Windows users to boot into multiple operating systems, including Ubuntu Linux.
Troubleshooting
This section applies to...
Dual-boot setups in which Windows was installed after Ubuntu
Conditions where Windows failure forced a re-installation
Windows recovery techniques involving the "restoration" of the MBR
Cases where GRUB failed to install
Prerequisites:
Your Ubuntu partitions are all still intact
You have a LiveCD, such as the Ubuntu Desktop CD or the Knoppix Live CD
You are familiar enough with your LiveCD to gain access to a console
You remember how you set up your partitions (having a printout of /etc/fstab is ideal, though you can make do with the output of
sudo fdisk -l /dev/sda
Knowledge of how your kernel works (specifically with regards to initrd), if you're using a non-Ubuntu kernel or you have built your own
Your kernel's version; this howto assumes 2.6.10-5-386
Preparing Your Working Environment
To begin the restoration procedure, insert your LiveCd and reboot your computer. Proceed with your LiveCD's bootup procedure until you are presented with an interface. To find how to open a command-line please click here] or try
Applications -> Accessories -> Terminal
Note: Since this is a LiveCD environment, any changes to user accounts or file-system layouts at this level will not be permanent. This means you can set a temporary root password and create directories without affecting your actual installation.
Now, you need to gain root access. Under Ubuntu, this can be done with the following commands:
sudo -i
Under Knoppix, the following command will suffice, and you will not be prompted for a password.
su -
Now that you have root access, you need to mount the partition(s) containing your boot-loader files.
You will need access to both your /sbin/ and /boot/ directories. If you have a /boot/ listing in your fstab, you are among those who will need to mount two partitions.
Begin by creating a mount point for your working environment -- you'll notice this is the same as creating a directory.
mkdir /mnt/work
If you need to mount /boot/, too, run the following command.
mkdir /mnt/work/boot
Now it's time to actually load your file-system data. Review your fstab and identify the location(s) of / and /boot/; these will likely look something like /dev/sda3 and /dev/sda4, though the letter 'a' and the numbers 3 and 4 may differ.
Note: For the remainder of this howto, /dev/sda3 and /dev/sda4 will be assumed, so alter them as needed when typing them in yourself.
Enter the following commands to load your file-system and some information GRUB may need.
mount /dev/sda4 /mnt/work
mount -o bind /dev /mnt/work/dev
mount -o bind /proc /mnt/work/proc
cp /proc/mounts /mnt/work/etc/mtab
Now, you have to enter your working environment. The following command will take care of that.
chroot /mnt/work/ /bin/bash
Warning: From this point on, any files you modify will affect your Ubuntu system. You have left the safety of the LiveCD. Exercise caution.
Recovering GRUB Automatically
If you have a separate /boot/ partition, type the following line.
sudo mount /dev/sda3 /boot/
Reinstalling GRUB from this point is easy. Just enter the following command.
sudo /sbin/grub-install /dev/sda
If the command you used above failed, which is unlikely, you will need to configure GRUB manually (it isn't too hard). If it succeeded, you should read the note at the start of the final section: "Configuring the GRUB Menu".
Recovering GRUB Manually
Before you can undertake the next step, it's important that you understand how GRUB identifies partitions.
To GRUB, numbers begin with 0, and letters are expressed numerically, also beginning with 0.
For example, /dev/sda1 is "hd0,0" to GRUB. Similarly, /dev/sdb3 is "hd1,2".
Note: The "root" line must point to the location of your /boot/ partition if you have one. If you do not have one, point it at your / partition.
sudo /sbin/grub
grub> root (hd0,2)
grub> setup (hd0)
grub> quit
Configuring the GRUB Menu
Note: This step does not need to be done if you're just trying to recover your MBR. Installing Windows will not alter the contents of your existing menu.lst, so if everything was working right before, everything will continue to work right now, and you can restart your computer.
Open the GRUB menu file,
sudo gedit /boot/grub/menu.lst
with your favourite text editor. We use Gedit as an example.
Note: Your menu.lst file is used to control the operating systems GRUB displays on start-up, as well as its visual appearance. This howto will only explain how to get your operating systems to boot, it will not tell you how to make your boot-loader pretty.
A sample menu.lst, stripped of unnecessary comments, appears below. It is based on the /dev/sda3 and /dev/sda4 example above, and assumes Windows resides at /dev/sda1.
timeout 5 #The number of seconds GRUB should wait before booting an OS
default 0 #The entry which should be booted by default
fallback 1 #The entry which should be booted in the event of the first one failing
title Ubuntu, 2.6.10 #A 32-bit Ubuntu entry
#This (or something like it) should be in your configuration
root (hd0,2)
initrd /initrd.img-2.6.10-5-386
kernel /vmlinuz-2.6.10-5-386 root=/dev/sda4
title Ubuntu, 2.6.10 #Another 32-bit Ubuntu entry
#This is an example of an Ubuntu entry which does not have a separate /boot/ partition
#(it is provided only as an alternate to the example above -- do not use them together)
root (hd0,2)
initrd /boot/initrd.img-2.6.10-5-386
kernel /boot/vmlinuz-2.6.10-5-386
title Microsoft Windows XP Home #An entry for a Windows installation
#If you're reading this guide, you probably want this
root (hd0,0)
makeactive
chainloader +1
And that's it. Save and close the file, then reboot and try out the entries.
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