UbuntuHelp:RecoveringUbuntuAfterInstallingWindows
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This page documents how to restore or recover from boot-loader related problem. Ubuntu uses the Grub bootloader, please refer to GrubHowto for more information on Grub.
Some common reasons for needing to repair your bootloader include installing Microsoft Windows after you have installed Ubuntu, adding or removing a hard drive, or even changing hard drive settings.
目录
Using the Ubuntu Desktop/Live CD
Overwriting the Windows bootloader
This will overwrite your Windows Boot Loader. In order to boot Ubuntu we will be overwriting the Windows Boot Loader. This is to be expected and is part of this guide.
WARNING
Do not use Ubuntu 9.10 live CD to restore the boot loader from a previous version. It will leave you with Grub in shell mode and no menu. If this happens, repeat the procedure with 9.04 or earlier -- preferably the same version that installed Grub originally. The first step is to boot from a Live CD and open a terminal. You will need to run a few commands as root. One option is to first run sudo -i which will send you to a root shell from which you will simply run the commands without the sudo prefix. Be extremely careful when running a root shell, especially for typos! Even an extra space can do massive damage to your system. Always backup on external media before attempting recovery if at all possible. Next we will need to find upon which partition your Ubuntu system is installed. Type the command fdisk -l. It will output a list of all your partitions. Example :
fdisk -l Disk /dev/hda: 120.0 GB, 120034123776 bytes 255 heads, 63 sectors/track, 14593 cylinders Units = cylinders of 16065 * 512 = 8225280 bytes Device Boot Start End Blocks Id System /dev/sda1 1 8 64228+ 83 Linux /dev/sda2 9 1224 9767520 83 Linux /dev/sda3 * 1225 2440 9767520 a5 FreeBSD /dev/sda4 2441 14593 97618972+ 5 Extended /dev/sda5 14532 14593 498015 82 Linux swap / Solaris /dev/sda6 2441 14530 97112862 83 Linux Partition table entries are not in disk order
Here are listed three Linux partitions. /dev/sda2 is the root partition, /dev/sda1 is the /boot partition and /dev/sda6 is the /home partition. If you only have one partition, this means that your entire Ubuntu system is installed on that one. Later there will be a section on how to determine which partition your Ubuntu installation is on if you have several different partitions. First, create a mountpoint for your partition, for example:
mkdir /media/root
Then mount your partition in it. If you don't know which one it is, then mount any of them, we will determine if it is the correct one.
mount /dev/sda2 /media/root
Replace /dev/sda2 with the correct name of your partition. To check if it is the correct one, run ls /media/root which should output something like this:
bin dev home lib mnt root srv usr boot etc initrd lib64 opt sbin sys var cdrom initrd.img media proc selinux tmp vmlinuz
If what you have looks nothing like this, the drive you have selected is incorrect. Run umount /media/root in the Terminal to unmount it then mount and try another one. Should you have made a /boot partition you can mount it like so:
mount /dev/sda1 /media/root/boot
To make sure this is indeed the /boot partition, run ls /media/root/boot, which should output 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
Once again, if what you have is not similar, unmount it and try another partition. Now that everything is mounted, we just need to reinstall GRUB:
sudo grub-install --root-directory=/media/root /dev/sda
If you get BIOS warnings try:
sudo grub-install --root-directory=/media/root /dev/sda --recheck
Note: 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. 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
Preserving Windows Bootloader
This method allows you to restore GRUB and keep the Windows bootloader as your primary bootloader. 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. 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.
Restoring GRUB
1. Boot from a Live CD, like Ubuntu Live, Knoppix, Mepis, or similar. Ideally use Ubuntu 8.04 or higher as this has NTFS write support and makes life a bit easier. Note that this isn't necessary, just more convenient. 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)". 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 bootloader, or you can continue and tell the Windows bootloader 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 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:
#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`.
Warning
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
From Inside Ubuntu
While you can run "grub" from the Ubuntu Desktop/Live CD, you can also recover grub from within your Ubuntu installation to make it work. To do this, mount your root partition (the following examples assume that the root partition is on hda1):
sudo mkdir /mnt/linux sudo mount /dev/hda1 /mnt/linux
then change directory to your installation sbin and run grub from there
cd /mnt/linux/sbin sudo ./grub
Using the Unofficial "Super Grub Disk"
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 Bootloader 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:
- Super Grub Disk (WITH HELP) :-)))
- Select: your language
- Select: 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
- You're done.
Using Microsoft Vista
If you have Vista installed and you installed Ubuntu and when you rebooted it didn't show up as a dual boot option, try going into Vista (since that is all you can do), use the program EasyBCD version 1.7 It looks like this: 模板:Http://aycu01.webshots.com/image/31560/2002188190250314159 rs.jpg Add your Linux install to the boot sequence.
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're 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
fdisk -l /dev/hda) - 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. If your LiveCD does not immediately present you with a console, also called a terminal, open one -- to do this with the Ubuntu LiveCD, click Applications -> System Tools -> Terminal. Note: Since this is a LiveCD environment, any changes to user accounts or filesystem 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 bootloader 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 filesystem data. Review your `fstab` and identify the location(s) of `/` and `/boot/`; these will likely look something like `/dev/hda3` and `/dev/hda4`, though the letter 'a' and the numbers 3 and 4 may differ.
Note: For the remainder of this howto, `/dev/hda3` and `/dev/hda4` will be assumed, so alter them as needed when typing them in yourself.
Enter the following commands to load your filesystem and some information GRUB may need.
mount /dev/hda4 /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/hda3 /boot/
Reinstalling GRUB from this point is easy. Just enter the following command.
sudo /sbin/grub-install /dev/hda
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/hda1` is "hd0,0" to GRUB. Similarly, `/dev/hdb3` 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, `/boot/grub/menu.lst`, with your favourite text editor. An example follows.
sudo nano /boot/grub/menu.lst
Note: Your `menu.lst` file is used to control the operating systems GRUB displays on startup, 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 bootloader pretty.
A sample `menu.lst`, stripped of unnecessary comments, appears below. It is based on the `/dev/hda3` and `/dev/hda4` example above, and assumes Windows resides at `/dev/hda1`.
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/hda4 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.
Using the Ubuntu Alternate/Install CD
This section explains how to rescue GRUB (the GRand Unified Boot loader), using the Ubuntu alternate/install CD ROM.
- 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 theXis a partition number. - you are then presented with a command prompt (a hash).
- type
$ grub-install /dev/hdaXwhere X is your Ubuntu root install.
The GUI Way: Using the Alternate/Install CD and Overwriting the Windows bootloader
- 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
GRUB Resources
- GRUB Manual
- GRUB homepage
- GrRUB wiki
- Linux+Win+Grub HowTo
- Super Grub Disk - Ready to go cdrom or floppy that restores Grub on MBR automatically
- GRUB for DOS
