[HOW TO] Get Your *nix Bootloader Back


Recommended Posts

I saw where Aaron had written the HOWTO Guide for getting the Windows bootloader back, but what if you're someone who needs their GRUB or LILO back? What then? Well, I found the answer for anyone who might need it :D

GRUB

  1. Boot into the first CD
  2. Type linux rescue when asked what to boot.
  3. After you have chosen Language and Keyboard layout, you are asked if you want to mount your harddisk system. Say yes to this.
  4. Now you system is mounted as /mnt/sysimage. Say 'OK'. Now type: chroot /mnt/sysimage. This will make you run on your already installed system, instead of the CD-ROM
  5. Type /sbin/grub-install /dev/hda (change hda to sda if you're using an SATA hard drive)

LILO

  1. Boot into the first CD
  2. Type linux rescue when asked what to boot.
  3. After you have chosen Language and Keyboard layout, you are asked if you want to mount your harddisk system. Say yes to this.
  4. Now you system is mounted as /mnt/sysimage. Say 'OK'. Now type: chroot /mnt/sysimage. This will make you run on your already installed system, instead of the CD-ROM. Now you can edit /etc/lilo.conf if something was wrong (vi /etc/lilo.conf and run lilo), or if you need to reinstall LILO just type lilo. The LILO installation process should now run.

This may be different for different distros and how you may have your system setup. I do not issue any guarantees with this HOWTO. Neowin, nor myself, is responsible if you bork your system. If you have any problems post them here ;)

Edited by Hurmoth
Link to comment
https://www.neowin.net/forum/topic/324741-how-to-get-your-nix-bootloader-back/
Share on other sites

Just an addendeum. You can install GRUB from within GRUB (this is how I like to do it).

1. Boot from a floppy or CD which uses GRUB as it's bootloader.

2. When you see GRUB's boot-menu, hit 'c'. You should see a "grub>" prompt

3. Type the following commands:

grub> root (hd0, 0)
grub> setup (hd0)

Commands explained:

"root (hd0, 0)" - This tells grub where it can find grub's files which are normally located in "/boot/grub/". The sample command tells grub that the files are located on the first hard drive, on partition 0 (first partition). If you don't know which drive/partition hold grub's files, you can do a:

grub> find /boot/grub/stage1

"setup (hd0)" - Tells grub to install itself on the Master Boot Record (MBR) of the first hard drive. You can also tell grub to install onto a partition by doing a "setup (hd0, 1)". This will tell grub to install to the second partition of the first hard drive.

Tips:

- Grub has a "help" command. Use it.

- Grub supports "bash-like" auto-completing. Say you don't quite know the partition number of your linux partition, but you know it's on the first hard drive and you know it's an ext2 partition. You can type:

grub> root (hd0,

and hit [tab]

This gives me:

Possible partitions are:
   Partition num: 0,  Filesystem type is reiserfs, partition type 0x83
   Partition num: 1,  Filesystem type is ext2fs, partition type 0x83
   Partition num: 2,  Filesystem type is reiserfs, partition type 0x83

Voila! It's partition number 1. Auto-completeing also works for other grub commands.

  markjensen said:
Anyone have an addition for doing this for LILO users?

585974127[/snapback]

If anyone adds it, I'll change the title and add it to my first post (giving the person credit of course) ;)

  markjensen said:
Good idea to have this posted (Y)  I have never had to do this, but many others have had to and have posted questions on it.

My boss' GRUB got messed up and wouldn't boot so I had to research how to fix it. The first place I looked was here and all I saw was Armeck's guide to getting the Windows bootloader back.

Yes this is a good post. My grub was messed too (error 18) and I couldn't fix it because Linspire Live couldn't detect my damn hard drive for some reason so I couldn't fix it. Also, when I attempted to go into linuxrecovery of the Debian cd, it wouldn't let me reinstall grub from there.

I added a way to reinstall LILO using the first installation disc, this can also be done with a Rescue Disc or Floppy Disk. I have never used LILO, so early this morning I installed a fresh copy of FC3 and used LILO instead of GRUB and messed it up on purpose to try and find out how to reinstall LILO... and that is what I came up with. Let me know if I have any typos :D

  • 7 months later...
  invalidbuffalo said:

I get the error:

/dev/hda: Not found or not a block device.

when I try to reinstall GRUB.

If you do an fdisk -l (that is a lowercase letter "L", not the number one), what do you get for drives listed? Do you have SATA drives?

  • 4 months later...
  wildworld_ammsa said:

i think this topic needs to be a Sticky. if some admin agrees, can he/she plz add it?

[Pinned]

This may not stay, but we'll see. There is a limit as to how many topics we can "pin". This is a good topic to have handy. :woot:

Barney

  • 4 weeks later...
  • 2 months later...
  • 1 month later...

Why lose it in the first place?

Its easy to avoid the entire unpleasantness when installing Linux onto a PC thats already hosts Windows, you just have to think about not upsetting precious windows, after all, its more finicky about its bootsector than Linux is.

Here's what i do:

Install linux.....wait until bootloader setup

Then

* Modify setting if needed to put bootloader on root partition (the partition that hosts \)

Then AFTER bootloader is written and anytime BEFORE you complete installation reboot:

* Switch to a terminal window form the setup GUI, on SuSE 10.1 for example i use CRTL ALT + F5.

* Put a floppy disk in your floppy drive

* Make a folder under /mnt, e.g. md /mnt/floppy (on some linuces, you may need to make an entirely different folder than floppy, as one may already exist and not be able to be written to - dont ask why, ive seen it, in this case try md /mnt/fdtemp etc.)

* Mount your floppy disk, e.g. mount -t vfat /dev/fd0 /mnt/floppy

* Type: dd if=/dev/hdaX of=/mnt/floppy/bootsec.lnx bs=512 count=1

Where X = the root partition number (e.g. /dev/hda11 as it is on mine)

* Browse to the floppy and make sure the bootsec.lnx file is there.

* Complete linux install and reboot into Windows

* Copy bootsec.lnx to c:\

* Keep floppy in a safe place, or copy the bootsec.lnx to a safe place.

* Open boot.ini in notepad

* Add "XXXX Linux" = c:\bootsec.lnx in the OS list under windows.

Where XXXX is the name of the linux or something witty and anti MS

* Save the file.

* Enjoy.

A few seconds work and thinking intelligently means you can avoid the whole bootsector drama completely and not upset either. I havent met a linux yet this isnt possible to use on.

As i said ive been using this since my first forays into Red Hat and Windows 2000, hasnt failed me yet.

Why lose it in the first place?

Its easy to avoid the entire unpleasantness when installing Linux onto a PC thats already hosts Windows, you just have to think about not upsetting precious windows, after all, its more finicky about its bootsector than Linux is.

Here's what i do:

Install linux.....wait until bootloader setup

Then

* Modify setting if needed to put bootloader on root partition (the partition that hosts \)

Then AFTER bootloader is written and anytime BEFORE you complete installation reboot:

* Switch to a terminal window form the setup GUI, on SuSE 10.1 for example i use CRTL ALT + F5.

* Put a floppy disk in your floppy drive

* Make a folder under /mnt, e.g. md /mnt/floppy (on some linuces, you may need to make an entirely different folder than floppy, as one may already exist and not be able to be written to - dont ask why, ive seen it, in this case try md /mnt/fdtemp etc.)

* Mount your floppy disk, e.g. mount -t vfat /dev/fd0 /mnt/floppy

* Type: dd if=/dev/hdaX of=/mnt/floppy/bootsec.lnx bs=512 count=1

Where X = the root partition number (e.g. /dev/hda11 as it is on mine)

* Browse to the floppy and make sure the bootsec.lnx file is there.

* Reboot into Windows

* Copy bootsec.lnx to c:\

* Keep floppy in a safe place, or copy the bootsec.lnx to a safe place.

* Open boot.ini in notepad

* Add "XXXX Linux" = c:\bootsec.lnx in the OS list under windows.

Where XXXX is the name of the linux or something witty and anti MS

* Save the file.

* Enjoy.

A few seconds work and thinking intelligently means you can avoid the whole bootsector drama completely and not upset either. I havent met a linux yet this isnt possible to use on.

As i said ive been using this since my first forays into Red Hat and Windows 2000, hasnt failed me yet.

  • 3 months later...

i really didn't understand the first post (i'm new to linux).

i had to reinstall winxp because dual booting Ubuntu corrupted winxp files.

I got it back by:

Boot the livecd.

Start a terminal.

sudo -i

grub

find /boot/grub/stage1 // Will print something like (hd0,1)

root (hd0,1)

setup (hd0)

quit

was easy for me :)

  • 1 month later...

Hi,

  Quote
Boot the livecd.

Start a terminal.

sudo -i

grub

find /boot/grub/stage1 // Will print something like (hd0,1)

root (hd0,1)

setup (hd0)

quit

I already had winxp installed on my PC and have just installed the latest Ubuntu 7.04, immediately upon reboot I received a grub error 22 and nothing booted! Thanks to my PDA net access and this forum I got my windows bootloader back and then have just followed the above info to try and get a boot screen back to be able to choose either winxp or ubuntu but with no joy.

I just tried the above and it all seemed to go ok (no errors within the terminal window), but when I rebooted my PC it just started up straight into windows xp again....!

Help!

  • 2 years later...

For GRUB2 under Ubuntu 9.10 I had to do the following after I broke my bootloader. It kept loading up the memtest after I played around with startupmanager and GRUB2 provided NO menu to choose the kernel :\

  1. Boot via LiveCD
  2. sudo fdisk -l (list hard drives)
  3. sudo mount /dev/sda1 /mnt (mount the hard drive)
  4. sudo mount --bind /dev /mnt/dev (mount other devices)
  5. sudo chroot /mnt (great power comes great responsibility)
  6. gedit /etc/default/grub (this loads up the GRUB2 options)
  7. Change GRUB_DEFAULT=3 to GRUB_DEFAULT= (aka first kernel in grub.cfg, mine was 3 pointing at memtest)
  8. update-grub (this updates that read-only /boot/grub/grub.cfg file)
  9. shutdown -r now (reboots your baby)

That's the procedure that worked for me, I have a single hdd with no special partitioning (just default installed).

All the above is broken down from the Wiki Grub2 page.

  • 5 years later...

Speaking of bootloaders!

 

I opted out from using GRUB (or other chain loaders) and use the EFI stub in the Linux kernel and then use efibootmgr to add the kernel and the parameters as a boot entry. I don't find a reason to load a bootloader which then loads the OS when you can make UEFI load the OS directly.

If the kernel gets damaged or you screw up the parameters then you can use the EFI shell (comes with the board) to manually load the kernel.

 

What I do is:

  Quote

 

efibootmgr -b 0000 -d /dev/sda -p 1 -c -L "Arch Linux EFI stub" -l /vmlinuz-linux -u "root=UUID=3e65a7c4-0a24-44d5-aeeb-e6da72343a34 rootfstype=btrfs rootflags=ssd,discard,noatime,space_cache,compress=lzo,autodefrag,subvol=archrootfs rw quiet initrd=/initramfs-linux.img"

The 0000 is the boot entry in the UEFI boot entry list index. The boot order can be chosen with efibootmgr. I only have two entries, 0000 and 0002 (EFI shell).

The EFI system partition is partition 1 (-p 1, which is default) on HD 0 (-d /dev/sda) and is mounted at /boot in the OS. Add the custom text and then tell it which file to load (-l /vmlinuz-linux).

You can't overwrite a boot entry so you have to delete the entry first. Not specifying the list index ("bootnum") and using the -c option (create) will make it create a new entry at a unused index.

I would highly recommend this if you don't have a lot of operating systems to boot or non-UEFI compliant operating systems. Sure, having custom boot entries for failsafe or recovery modes won't be there but you can create entries for those too or even create shell commands that you can use in the EFI shell. The wiki for Arch Linux covers this subject and works on all kernels that has the EFI stub compiled into it.

 

Requirements: GPT on the drive and a UEFI system patition (a minimum 100MB or more depending on the size of the kernel(or kernels you want to load) and the standard says that it SHOULD be the first partition on the disk.

 

BTW: Don't mind the autodefrag root mount option, it only defrags metadata, it removes dead meta data, moves meta data etc, and does not do actual sector defragmentation.

  • Brandon H unpinned this topic
This topic is now closed to further replies.
  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Posts

    • Google Sheets gets exciting Gemini feature that is still missing in Excel by Usama Jawad We recently learned that Copilot in Microsoft Excel got a big upgrade in the form of context awareness, which is in addition to the formula generation capabilities that were made available earlier. However, no firm has really won the AI race yet, and Google has now edged ahead in at least one domain today, by adding Gemini text generation capabilities in Google Sheets. In a blog post, Google has announced that while you can already leverage Gemini in Sheets to generate charts and insights, you can now generate text using its new AI function too. This function can utilize a natural language prompt and an optional context window to summarize and generate text, categorize information, and perform sentiment analysis. The syntax for the AI function is fairly straightforward: AI("prompt",[optional range]) So you can invoke the Gemini function as follows: =AI("Perform sentiment analysis on the emails sent by the customers to the barbershop.", C2) Or: =AI("Create an email to the reviewer addressing specific items in their reviews.", A2:G2) It is very interesting to note that a similar capability is not offered by Copilot in Excel yet. In my testing, I did get Copilot to generate charts, formulas, and do some text formatting, it simply doesn't seem to have the ability to actually generate textual data directly in a workbook just yet. While an input range isn't mandatory, Google recommends using it for the best results. Just like any cell using a formula, you can refresh the AI cell, and get an indicator about its sync state. That said, a limitation that is present with regards to the AI function is that it only works for the first 200 selected cells in your range. Once that generation completes, you can select more cells and repeat the process, which is a slightly cumbersome experience. The rollout for this capability has begun across Business, Enterprise, Education, Education Premium, AI Pro, and Ultra plans, so it should be available to everyone sooner rather than later. In the meantime, you can view details about the AI function here.
    • Space Marine 2 gains a horde mode and DLSS 4 with new Siege update by Pulasthi Ariyasinghe Warhammer 40,000: Space Marine 2 just received its next major update. Dubbed the Siege update, it is finally bringing the long-promised horde mode for the third-person action game, as well as new tech for PC gamers. The Siege mode takes place on a fortified Imperial stronghold on Kadaku that is enduring endless attacks by Tyranids and Thousand Sons. There are three sections in total that players will defend in order before circling back to the original position, fighting away thousands of enemies in five waves before swapping locations. To give players a small break, there's a one-minute gap between each wave to resupply and purchase perks from the points they collect while in battle. Players can call in AI-controlled specialized soldiers, Space Marines, or even a Dreadnought to help out if the waves get a little too tough. To cap it all off, every fifth wave a boss encounter kicks off. There are 15 waves to go through in a single session, but parties can also kick off an endless mode at the end of these to see how far they can get. "Siege Mode expands on our PVE operations, emphasizing endless enemy waves that challenge even the strongest teams," says Focus Entertainment, describing the new mode. "When overwhelmed, players may call reinforcements for assistance. Engage in intense battles across three distinctive sectors, each requiring strategic adaptation. Side objectives emerge during combat, providing essential resources used to summon elite Space Marines or a formidable Dreadnought, drastically shifting battlefield dynamics. Over on PC, the studio has added two new options. One is RTAO (Ray-Traced Ambient Occlusion), though this is currently listed as an experimental feature. Next, Nvidia 5000 series graphics card owners can now enable DLSS 4 for better upscaling tech as well as multi-frame generation. The complete patch notes for Patch 8, which includes details on the balance changes, can be found here. The Warhammer 40,000: Space Marine 2 Siege update is now available on PC, Xbox Series X|S, and PlayStation 5.
    • Microsoft updates Media Creation Tool with a newer Windows 11 release by Taras Buria If you want to download a Windows 11 image or create an install media, the Media Creation Tool app is one of the best options—simple, fast, and, more importantly, official. While there are other useful alternatives, such as Rufus, Media Creation Tool remains the default choice for those who simply want a clean Windows 11 installation on a supported computer. Thanks to the latest MCT update, you will have to deal with fewer updates after installing Windows 11. Microsoft has quietly updated the Media Creation Tool app so that it downloads the latest Windows 11 release, version 24H2, with build number 26100.4349. This is the most recent public Windows 11 update (June 2025 Patch Tuesday), which eliminates the need to download large updates for your PC after installing the operating system. You can download Media Creation Tool from the official Windows 11 website. If you are familiar with it, this simple app can generate a Windows 11 image with the language you need or create a bootable USB media. Note that it only works on Windows, so Linux or macOS users have to download Windows images directly from the official website and then use apps that are available on their platforms. Another thing worth noting is Media Creation Tool is not the right choice if you want to install Windows 11 on an unsupported PC. In such a case, you can use MCT to download an ISO and then create a modified install media with apps like Rufus or Ventoy as described in our dedicated guide. If you want a more exotic Windows 11 Edition, try the Oofhours Media Tool, which allows you to select Windows 10 or 11, architecture (x64, x86, or ARM64), language, and edition. In addition to standard Home and Pro, the application can download non-mainstream SKUs, such as Enterprise, Education, or Professional for Workstations. Via: Deskmodder
    • Putting premium on your higher end laptops really makes it feel like your lower end laptops are worse.
  • Recent Achievements

    • Conversation Starter
      Kavin25 earned a badge
      Conversation Starter
    • One Month Later
      Leonard grant earned a badge
      One Month Later
    • Week One Done
      pcdoctorsnet earned a badge
      Week One Done
    • Rising Star
      Phillip0web went up a rank
      Rising Star
    • One Month Later
      Epaminombas earned a badge
      One Month Later
  • Popular Contributors

    1. 1
      +primortal
      541
    2. 2
      ATLien_0
      207
    3. 3
      +FloatingFatMan
      175
    4. 4
      Michael Scrip
      148
    5. 5
      snowy owl
      119
  • Tell a friend

    Love Neowin? Tell a friend!