HOWTO: Boot & Install Ubuntu from the Grub Rescue Prompt

[drs305]

HOWTO: Boot & Install Ubuntu from the Grub Rescue Prompt

This guide will detail how to boot an Ubuntu Live CD ISO from the "grub rescue>" prompt. The procedure will also work from the "grub>" prompt for Grub 2 users. I started this thread to help netbook users who are unable to mount the Live CD to resolve Grub problems on a previously-working installation. No CD is required. While writing the guide, I realized there might be others who could also use the instructions so I removed references to "Netbook" from the title.

Preconditions

This procedure will work for:

Ubuntu family releases using Grub 2
Malformed Grub 2 menu (grub.cfg)
Missing Linux kernels & initramfs images
Corrupted system folders (not including the module folder)


In order for this procedure to work, you must:

Have an Ubuntu family Live CD ISO image on a partition accessible from the Grub rescue prompt.
Grub modules from a previous installation must be found and properly loaded.


The procedure will not work for:

Missing Grub 2 modules (normally in /boot/grub or /usr/lib/grub/i386-pc )
Corrupted Ubuntu ISO images
Corrupted partition structure - "ls" returns only "(hd0)"



Boot Procedure

Download the ISO.

Download an Ubuntu ISO from: http://www.ubuntu.com/desktop/get-ubuntu/download (http://www.ubuntu.com/desktop/get-ubuntu/download)
or
Download an Ubuntu Netbook ISO from: http://www.ubuntu.com/netbook/get-ubuntu/download (http://www.ubuntu.com/netbook/get-ubuntu/download)



Locate the Ubuntu partition and the folder containing the Grub modules.
The Grub folder containing the modules must be located so the correct modules can be loaded. This folder would have been created during the initial installation of Ubuntu and should be located in the Ubuntu partition. This folder would normally be located at either (hdX,Y)/boot/grub or (hdX,Y)/usr/lib/grub/i386-pc


Find your existing Ubuntu partition and the module folder.


ls # List the known drives (hdX) and partitions (hdX,Y)
ls (hdX,Y)/ # List the contents of the partition's root
ls (hdX,Y)/boot/grub # Normal location of the Grub 2 modules.
ls (hdX,Y)/usr/lib/grub/i386-pc # Alternate location of the Grub 2 modules.


ls - should return all known drives (hdX) and partitions (hdX,Y)
ls (hdX,Y)/ - should show the contents of the root directory of the partition.

If you get an "error: unknown filesystem" this is not your Ubuntu partition; more on that later.
If this is the Ubuntu partition, you will see the Ubuntu folders, including lost+found/, home/, boot/ and vmlinuz and initrd.img. Use this address as the first part of the next command.


ls (hdX,Y)/boot/grub - should display several dozen *.mod files. This is the folder you are looking for.

If you don't find the modules, try the alternate location: ls (hdX,Y)/usr/lib/grub/i386-pc




Load the modules.

set prefix=(hdX,Y)/<path to modules>
This command must correctly point to the folder containing the Grub modules. The address should be the one in the previous section which displayed the modules.
Examples:
set prefix=(hd0,5)/boot/grub
set prefix=(hd1,1)/usr/lib/grub/i386-pc

Load modules:


insmod linux
insmod loopback
insmod iso9660
insmod fat # If ISO is located on fat16 or fat32 formatted partition.
insmod ntfs # If ISO is located on an NTFS formatted partition.
insmod nftscomp # If NTFS compression is used on the partition. Load if you aren't sure.


A "file not found" error means that the path in the prefix is incorrect or the specific module does not exist. The prefix setting may be reviewed with the set command. Rerun the "set prefix=" command with the proper path.


Locate the Ubuntu ISO file.
Using the same combinations of ls commands, locate the Ubuntu ISO image.



ls (hdX,Y)/


You are looking for contents including the ISO, such as ubuntu-10.04.1-desktop-i386.iso
Expand the path if the ISO image is not located in the / folder.
If you receive an error: unknown filesystem you may need to load the filesystem module (such as ntfs or fat. Return to the previous section for guidance.



Create the loopback device.


loopback loop (hdX,Y)/<path to ISO>/<ISO-name.iso>Example:
loopback loop (hd1,1)/ubuntu-10.04.1-desktop-i386.iso


Load the Linux kernel and initrd image.


set root=(loop)
linux /casper/vmlinuz boot=casper iso-scan/filename=/<ISO-name.iso> noprompt noeject
initrd /casper/initrd.lz

If the path to the ISO or filename is not correct, the boot will halt at the BusyBox screen and produce a message stating "can't open /dev/sr0: No medium found".

Note: If the ISO file is not in the / folder, include the path in the iso-scan/filename= entry. See second example.

Examples:
linux /casper/vmlinuz boot=casper iso-scan/filename=/ubuntu-10.04.1-desktop-i386.iso
linux /casper/vmlinuz boot=casper iso-scan/filename=/my-iso/ubuntu-10.04.1-desktop-i386.iso


Boot.
That should be it. If the commands ran without any messages/errors, the commands were accepted as entered. It's now time to boot:


boot



Install Ubuntu - From Live CD ISO

Note on Oneiric Daily ISO Installs: The current daily build of Oneiric Ocelot requires login to get to the Desktop. Choosing the default user will not allow use of 'sudo' as no password exists for the user. Select 'Other', then username 'Ubuntu' and leave the password field blank. This will allow the use of 'sudo' to unmount the /isodevice during the installation process.

Installation onto your hard drive is possible from a booted ISO file. A CD is not required. An Internet connection is recommended but not required. Without a connection packages installed from the ISO will not be updated and additional packages will not be downloaded.


Boot to the Live CD Desktop using the above ISO boot procedure.

Note: If you have a large amount of RAM you may be able to use the toram option. This will allow the system to boot into memory and permit automatic unmounting of the isodevice1 during the installation. /isodevice must be unmounted for a successful installation. If /isodevice cannot be unmounted by the installer, the installation will fail unless the user forces its unmounting. This forced unmounting is included in the procedure detailed later in this section.


If you would like to try the toram option, replace the linux line in the above and use this one instead:

linux /casper/vmlinuz boot=casper iso-scan/filename=/<ISO-name.iso> noprompt noeject toram --
If /isodevice can be unmounted by the installer at the prompt, the installation will continue.
If you have insufficient memory (it failed on my system with 3GB) and start the installation, the installer will be unable to unmount /isodevice, the install will fail and the system may freeze. Reboot and complete all the steps in the "Boot Procedure" section. Do not repeat this subsection and continue below.



Open a terminal: Applications, Accessories, Terminal


Unmount /isodevice

sudo umount -l -r -f /isodevice

Start the installation procedure by double-clicking the "Install Ubuntu" icon.


The installation will proceed as would any installation of the same release, similar to the Alternate CD.


During the latter stages of the installation (Step 8 in Ubuntu 10.04), you may see an "Advanced" button. If so, this is how you access the Grub installation options.



Install Ubuntu - Network Install

This procedure can be used on low-memory systems or by users who otherwise wish to download the installation files from the Internet. The process uses the free services of "netboot.me (http://www.netboot.me/)". The installer will attempt to connect to the Internet and download the installation files. Once the initial files are downloaded, the installation is similar to that of the Alternate CD installation.

Download the netbootme.iso from the link under the "Booting from CD" section of this page (http://www.netboot.me/gettingstarted).

You can download the ISO via any means available: Windows, terminal with wget, etc.
Note where the netbootme.iso is located on your drive. You will need to know the (hdX,Y) partition and path (if not stored in the root directory).
While this guide focuses on ISO booting, netboot.me offers other installation options, such as USB booting, which the user may wish to consider.



From the "grub rescue>" or "rescue" prompt, run the following commands. For detailed guidance, refer to the previous sections.



set prefix=(hdX,Y)/boot/grub
insmod loopback
insmod iso9660
insmod fat # If ISO is located on fat16 or fat32 formatted partition.
insmod ntfs # If ISO is located on an NTFS formatted partition.
insmod nftscomp # If NTFS compression is used on the partition. Load if you aren't sure.
loopback loop (hdX,Y)/<path if not in root directory of hdX,Y>/netbootme.iso # Example: loopback loop (hd1,1)/myiso/netbootme.iso
linux16 (loop)/GPXE.KRN
boot


Installer Notes

Once the netboot.me installation begins, select the installation you desire. For the standard Ubuntu installation, make the following selections:

Installers > Linux > Ubuntu > Version (Look in the status bar for the 32-bit/i386 or 64-bit/amd64, as the links are named the same).
Other operating systems are also available for installation from the main menu display.


During the latter stages of the download and installation, download options are presented. Normally the user will want to include the "Ubuntu Desktop".




Other drs305 Grub 2 Links:

5 Common Tasks (http://ubuntuforums.org/showthread.php?t=1302743)
ISO Booting with Grub 2 Menu Entries (http://ubuntuforums.org/showthread.php?t=1549847)
Password Protection (http://ubuntuforums.org/showthread.php?t=1369019)
Purge and Reinstall Grub 2 from the Live CD (http://ubuntuforums.org/showthread.php?t=1581099)
Title Tweaks (http://ubuntuforums.org/showthread.php?t=1287602)

Grub 2 (https://help.ubuntu.com/community/Grub2) (help.ubuntu.com)

[kamaru44ken]

i tried the command 'insmod linux' but an error occured:

grub rescue> insmod linux
error: invalid object file.

What causes the error? Additional details:
grub rescue> ls
(hd0) (hd0,msdos5) (hd0,msdos3) (hd0,msdos2) (hd0,msdos1)
grub rescue> ls (hd0,2)/
./ ../ lost+found/ var/ etc/ media/ bin/ boot/ ...
grub rescue> ls (hd0,2)/boot/grub/
...(many .mod files) ... grubenv core.img grub.cfg
grub rescue> set prefix=(hd0,2)/boot/grub
grub rescue> set
prefix=(hd0,2)/boot/grub
root=hd0,2
grub rescue> insmod linux
error: invalid object file
grub rescue>

I also tried setting the prefix to usr/lib/grub/i386-pc but the same error occured

[drs305]

i tried the command 'insmod linux' but an error occured:
I also tried setting the prefix to usr/lib/grub/i386-pc but the same error occured

If you are still having problems, try to add the module by using the entire address:

insmod (hd0,2)/boot/grub/linux.mod

For what you have posted, you can try this sequence to boot:


set prefix=(hd0,2)/boot/grub
set root=(hd0,2)
insmod (hd0,2)/boot/grub/linux.mod
linux /vmlinuz root=/dev/sda2 ro
initrd /initrd.img
boot

[jmrat]

If you are still having problems, try to add the module by using the entire address:

insmod (hd0,2)/boot/grub/linux.mod

For what you have posted, you can try this sequence to boot:


set prefix=(hd0,2)/boot/grub
set root=(hd0,2)
insmod (hd0,2)/boot/grub/linux.mod
linux /vmlinuz root=/dev/sda2 ro
initrd /initrd.img
boot

I used bottom part worked great untill shut down. than the same thing happened and had to do all over again what should i do? also my computer usually asks if i want to boot win7 or ubuntu and it stoped what could be causing this?

[drs305]

I used bottom part worked great untill shut down. than the same thing happened and had to do all over again what should i do?

Changes made at the grub prompt are non-persistent (as you found). Do the procedure again. Once booted into your normal installation, run:

sudo update-grub
sudo blkid -c /dev/null

Compare the UUID for your Ubuntu partition in /boot/grub/grub.cfg (in the default menuentry) with the results from the second command and make sure they are the same. The update-grub command should have corrected any mis-identified UUIDs, but check to be sure they are all correct.

If you still have problems, you could try disabling the UUID entry in /etc/default/grub to see if that fixes things (Note it may be slightly different wording, depending on the version of Grub2 you are using). In any case, remove the # symbol.

GRUB_DISABLE_LINUX_UUID="true"

[egor123]

HI!
i have problems booting my ubuntu as i always get this grub prompt
so i try to boot it from here
when i start looking for the ubuntu .iso file is most directories like ls (hd0,1)/home or most of other folders i get error: out of disk
what should that mean?
thank you

[drs305]

HI!
i have problems booting my ubuntu as i always get this grub prompt
so i try to boot it from here
when i start looking for the ubuntu .iso file is most directories like ls (hd0,1)/home or most of other folders i get error: out of disk
what should that mean?
thank you

egor123,

'out of disk' can be caused by many things. Often it means the BIOS cannot read the drive. You should probably open up your BIOS setup during boot and check the reported drive size. If the BIOS does not report the full size of your drive, any files physically located beyond the limit seen by the BIOS will not be found.

At the grub prompt, when investigating I usually start with "ls" to see what partitions Grub2 sees, then go deeper step by step. Next "ls (hd0,1)/", then "(hd0,1)/boot" and then "(hd0,1)/boot/grub" for instance.

If Grub 2 can't find the file(s) with the 'ls' command, it won't be able to use them to boot.

[chah]

Hi DRS305, Thanks so much for all your time and effort, in writing the guide as well as answering questions!

I've got a new Dell Vostro 3300. I posted something in the Dell subforum, but I'm not sure whether what I'm experiencing is specific to Dell.

I followed the instructions in this thread, and it goes through all the way to the end. After typing "boot", some words and numbers fly by on the screen. Then the screen goes blank and it hangs there, indefinitely.

I'm able to boot this machine using a USB key that I created using Unetbootin. I've been going in and editing grub.cfg and rebooting trying to find out what's the problem, until I came across this set of instructions. Now I can now enter line-by-line to see what's wrong. But at this time, all the commands go through, but it still hangs.

Any thoughts?

Thanks!

[drs305]

Now I can now enter line-by-line to see what's wrong. But at this time, all the commands go through, but it still hangs.
Any thoughts?


chah,

It sounds like a video problem more than a grub problem. Grub will either pass control to the kernel or if it can't boot will produce an error message or grub prompt. Since you have neither of those the chances are good that it's kernel related.

If you have Maverick or earlier, and a blinking cursor on a blank screen, try editing the menu during boot (hold down the SHIFT key if you don't see the menu). Press 'e' to edit the top entry, then cursor to the 'linux' line. Remove quiet splash and add nomodeset. Then press CTRL-x to boot.

If it boots to the Desktop, System, Administration, Additional Drivers and add a driver for your video card to see if that fixes things.

If you have Natty, there have been some problems with the Grub/kernel interface. I'm going to give you a link, but it is major work wading through it all. For starters, you could try the above, but also remove vt.handoff=7 and add vga=771. Try that first, then try nomodeset if that doesn't work.

Let us know if you have success with any of these methods.

[chah]

Hi DRS,

Thanks for the tips. I also thought it might be a video problem when it happened. However, I listened for the ubuntu start-up sound and did not hear it. Incidentally, I'm using Natty.

So just to update what happened, I finally did the regular install, instead of booting from the ISO with persistence. It was a bit strange, the regular install crashed twice when I tried to do it from my office (I turned on updates and third party drivers). However when i came home, the installation seemed to work. For some reason though, it told me that my laptop does not have the hardware to support Unity, even though Unity was working when I boot from the Unetbootin USB key. I tried digging through the boot/grub/*.cfg file on the Unetbootin thumbdrive in the past, but copying parameters from that file into my own boot grub.cfg file didn't seem to work either. I don't suppose you have any information about how Unetbootin is able to boot or how I can copy its GRUB2 parameters to my HDD boot partition? This is out of curiosity as I'm fine without Unity.

I may come back to this at some point in the future. Thanks for your help.

[drs305]

chah,

Thanks for the update. I received the same messages about not having the hardware to support Unity. In my case, it simply meant that I had to install the proprietary drivers for my video card (Nvidia).

I'm running Unity and I can't remember what the panel looked like when I first installed Natty Alpha - so I don't remember what the non-Unity menu looked like. In earlier releases you would get to the Additional Drivers page via System, Administration, Additional Drivers. In my case (with an older Nvidia GS 7600) Natty found it without problem. As soon as I installed and rebooted Unity worked fine.

Best of luck.

[johny why]

hi, noob here, not sure this thread can help me.

i have a linux livecd iso, and a laptop running ubuntu. i want to install this is to the hard drive from inside linux (or at the linux boot prompt,which i gather is possible?)

any suggestions?

thanks!

[Flashyman]

If you are still having problems, try to add the module by using the entire address:

insmod (hd0,2)/boot/grub/linux.mod

For what you have posted, you can try this sequence to boot:


set prefix=(hd0,2)/boot/grub
set root=(hd0,2)
insmod (hd0,2)/boot/grub/linux.mod
linux /vmlinuz root=/dev/sda2 ro
initrd /initrd.img
boot
Thank you so much!
I had ubuntu installed and messed up something and ended up getting grub command (grub>) anytime I booted, I nearly grabbed the live cd to give up and completely reinstall the whole thing.

the other commands weren't working as in I couldn't find any ubuntu .iso file so it was giving errors.

By entering the commands you specified there with some minor adjustments as to what my drives are named, I am now able to boot back into ubuntu!!!! Thank you very much drs305, you are hereby my hero!


(btw, somehow my drives are named like: (hd0,msdos1) and (hd1,msdos1) I would love to get rid of this msdos text if possible, if only for the looks of it, I hate everything MS, so that includes msdos.... but I guess these steps require advanced techniques which would probably make me end up in the same situation again (grub>))

[drs305]

(btw, somehow my drives are named like: (hd0,msdos1) and (hd1,msdos1) I would love to get rid of this msdos text if possible, if only for the looks of it, I hate everything MS, so that includes msdos.... but I guess these steps require advanced techniques which would probably make me end up in the same situation again (grub>))

Yes the partitions are now named 'msdos'... The good news is that if you have problems in the future you may be able to avoid the command line entirely and use the Boot Repair app to fix things. It's been developed within the past year and does a very good job of salvaging Grub 2 problems.

Boot-Repair-Disk (http://ubuntuforums.org/showthread.php?t=1831869)

[volinkov]

Ok, I installed 10.04 on an external hard drive, and used grubrescue to boot it. I decided that I didn't want 10.04, so I installed 11.10 on my hard drive. Now, when I try to load the grub modules, grub can't find the files. I know that they are there, because when I boot up with a live cd, I can find them. Any suggestions?

[drs305]

Ok, I installed 10.04 on an external hard drive, and used grubrescue to boot it. I decided that I didn't want 10.04, so I installed 11.10 on my hard drive. Now, when I try to load the grub modules, grub can't find the files. I know that they are there, because when I boot up with a live cd, I can find them. Any suggestions?

volinkov,

Welcome to the Ubuntu Forums. We need more information. Please download and run the boot info script. Copy the contents of the RESULTS.txt it generates and post it here. The file will show us the status of your boot files and help us determine what went wrong.

Boot Info Script (http://bootinfoscript.sourceforge.net)

[volinkov]

When I try to run the script, it returns:
boot_info_script version 0.60

"gawk could not be found, using "busybox awk" instead.
This may lead to unreliable results.

[: 326: busybox awk: unexpected operator
boot_info_script.sh: 353: syntax error: "(" unexpected ( expecting "fi")

I tried running the script straight from the downloads directory while booted with a live cd, and then I put the files onto my external drive and tried running them from the home directory there. I got the same error both times.

[drs305]

volinkov,

You can install 'gawk' although the script can run with 'awk'.

You might try installing and running the Boot Repair Tool. It may be able to fix your grub problem by itself, and if not it contains the Boot Info Script files and the script will run from within that app.

Boot Repair Tool (http://ubuntuforums.org/showthread.php?t=1769482)

[volinkov]

Sorry if Im asking you too many questions, but do I install gawk and the boot repair while my computer is booted with a live cd? I guess I forgot to mention that I dont have an internal hard drive. My computer has fried two, so Im trying to boot strictly from an external usb drive. Do I somehow install the boot repair to the usb drive? Thanks for your patience!

[drs305]

Sorry if Im asking you too many questions, but do I install gawk and the boot repair while my computer is booted with a live cd? I guess I forgot to mention that I dont have an internal hard drive. My computer has fried two, so Im trying to boot strictly from an external usb drive. Do I somehow install the boot repair to the usb drive? Thanks for your patience!


If you are going to run the script from the LiveCD, you can install 'gawk' there as well. It's installation will only last until you reboot. It's not critical to have gawk, but it will eliminate the messages. The same for the Boot Repair app.

I believe Boot Repair can be installed and run from the LiveCD, but better yet would be to create a Boot Repair CD so you can boot directly from it.

If you install Boot Repair while running the LiveCD you may be able to fix the problem at that point. Again, once you reboot using the LiveCD the Boot Repair app will no longer be available until you reinstall it.

[volinkov]

I ran the boot repair, and it updated the grub modules on my hard drive, which I confirmed. I then went to boot from the hard drive, but I am still having the same problem with grub rescue.

Using the "ls" command, it returns (hd0) (hd0,msdos1)
The second one is my external drive.
Using ls (hd0,msdos1)/ returns all of the directories and files in the home directory. Awesome.
Next, when I try to use "ls (hd0,msdos1)/boot/grub/" ,which is where the grub directory and modules are , it returns "error:file not found". If I just use "ls (hd0,msdos1)/boot/" it doesn't error, but it also doesn't return any of the files/directories that I know are in there.

Is my grub broken?

Also, I got the results.txt file:

Boot Info Script 0.60 from 17 May 2011


============================= Boot Info Summary: ===============================

=> Grub2 (v1.99) is installed in the MBR of /dev/sda and looks at sector 1 of
the same hard drive for core.img. core.img is at this location and looks
for on this drive.

sda1: __________________________________________________ ________________________

File system: ext4
Boot sector type: -
Boot sector info:
Operating System: Ubuntu 11.10
Boot files: /boot/grub/grub.cfg /etc/fstab /boot/grub/core.img

sda2: __________________________________________________ ________________________

File system: Extended Partition
Boot sector type: -
Boot sector info:

sda5: __________________________________________________ ________________________

File system: swap
Boot sector type: -
Boot sector info:

============================ Drive/Partition Info: =============================

Drive: sda __________________________________________________ ___________________

Disk /dev/sda: 500.1 GB, 500107859968 bytes
255 heads, 63 sectors/track, 60801 cylinders, total 976773164 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes

Partition Boot Start Sector End Sector # of Sectors Id System

/dev/sda1 * 2,048 968,452,095 968,450,048 83 Linux
/dev/sda2 968,454,142 976,771,071 8,316,930 5 Extended
/dev/sda5 968,454,144 976,771,071 8,316,928 82 Linux swap / Solaris


"blkid" output: __________________________________________________ ______________

Device UUID TYPE LABEL

/dev/loop0 squashfs
/dev/sda1 c115a6e2-5b2a-4b13-a810-6373cec0e25e ext4
/dev/sda5 b39b8a64-11c5-48f4-a44e-c507334989a1 swap

================================ Mount points: =================================

Device Mount_Point Type Options

/dev/loop0 /rofs squashfs (ro,noatime)
/dev/sr0 /cdrom iso9660 (ro,noatime)


=========================== sda1/boot/grub/grub.cfg: ===========================

--------------------------------------------------------------------------------
#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#

### BEGIN /etc/grub.d/00_header ###
if [ -s $prefix/grubenv ]; then
set have_grubenv=true
load_env
fi
set default="0"
if [ "${prev_saved_entry}" ]; then
set saved_entry="${prev_saved_entry}"
save_env saved_entry
set prev_saved_entry=
save_env prev_saved_entry
set boot_once=true
fi

function savedefault {
if [ -z "${boot_once}" ]; then
saved_entry="${chosen}"
save_env saved_entry
fi
}

function recordfail {
set recordfail=1
if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi
}

function load_video {
insmod vbe
insmod vga
insmod video_bochs
insmod video_cirrus
}

insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root c115a6e2-5b2a-4b13-a810-6373cec0e25e
if loadfont /usr/share/grub/unicode.pf2 ; then
set gfxmode=auto
load_video
insmod gfxterm
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root c115a6e2-5b2a-4b13-a810-6373cec0e25e
set locale_dir=($root)/boot/grub/locale
set lang=en_US
insmod gettext
fi
terminal_output gfxterm
if [ "${recordfail}" = 1 ]; then
set timeout=10
else
set timeout=10
fi
### END /etc/grub.d/00_header ###

### BEGIN /etc/grub.d/05_debian_theme ###
set menu_color_normal=white/black
set menu_color_highlight=black/light-gray
if background_color 44,0,30; then
clear
fi
### END /etc/grub.d/05_debian_theme ###

### BEGIN /etc/grub.d/10_linux ###
if [ ${recordfail} != 1 ]; then
if [ -e ${prefix}/gfxblacklist.txt ]; then
if hwmatch ${prefix}/gfxblacklist.txt 3; then
if [ ${match} = 0 ]; then
set linux_gfx_mode=keep
else
set linux_gfx_mode=text
fi
else
set linux_gfx_mode=text
fi
else
set linux_gfx_mode=keep
fi
else
set linux_gfx_mode=text
fi
export linux_gfx_mode
if [ "$linux_gfx_mode" != "text" ]; then load_video; fi
menuentry 'Ubuntu, with Linux 3.0.0-12-generic-pae' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
set gfxpayload=$linux_gfx_mode
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root c115a6e2-5b2a-4b13-a810-6373cec0e25e
linux /boot/vmlinuz-3.0.0-12-generic-pae root=UUID=c115a6e2-5b2a-4b13-a810-6373cec0e25e ro quiet splash vt.handoff=7
initrd /boot/initrd.img-3.0.0-12-generic-pae
}
menuentry 'Ubuntu, with Linux 3.0.0-12-generic-pae (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root c115a6e2-5b2a-4b13-a810-6373cec0e25e
echo 'Loading Linux 3.0.0-12-generic-pae ...'
linux /boot/vmlinuz-3.0.0-12-generic-pae root=UUID=c115a6e2-5b2a-4b13-a810-6373cec0e25e ro recovery nomodeset
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-3.0.0-12-generic-pae
}
submenu "Previous Linux versions" {
menuentry 'Ubuntu, with Linux 3.0.0-12-generic' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
set gfxpayload=$linux_gfx_mode
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root c115a6e2-5b2a-4b13-a810-6373cec0e25e
linux /boot/vmlinuz-3.0.0-12-generic root=UUID=c115a6e2-5b2a-4b13-a810-6373cec0e25e ro quiet splash vt.handoff=7
initrd /boot/initrd.img-3.0.0-12-generic
}
menuentry 'Ubuntu, with Linux 3.0.0-12-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os {
recordfail
insmod gzio
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root c115a6e2-5b2a-4b13-a810-6373cec0e25e
echo 'Loading Linux 3.0.0-12-generic ...'
linux /boot/vmlinuz-3.0.0-12-generic root=UUID=c115a6e2-5b2a-4b13-a810-6373cec0e25e ro recovery nomodeset
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-3.0.0-12-generic
}
}
### END /etc/grub.d/10_linux ###

### BEGIN /etc/grub.d/20_linux_xen ###
### END /etc/grub.d/20_linux_xen ###

### BEGIN /etc/grub.d/20_memtest86+ ###
menuentry "Memory test (memtest86+)" {
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root c115a6e2-5b2a-4b13-a810-6373cec0e25e
linux16 /boot/memtest86+.bin
}
menuentry "Memory test (memtest86+, serial console 115200)" {
insmod part_msdos
insmod ext2
set root='(hd0,msdos1)'
search --no-floppy --fs-uuid --set=root c115a6e2-5b2a-4b13-a810-6373cec0e25e
linux16 /boot/memtest86+.bin console=ttyS0,115200n8
}
### END /etc/grub.d/20_memtest86+ ###

### BEGIN /etc/grub.d/30_os-prober ###
### END /etc/grub.d/30_os-prober ###

### BEGIN /etc/grub.d/40_custom ###
# This file provides an easy way to add custom menu entries. Simply type the
# menu entries you want to add after this comment. Be careful not to change
# the 'exec tail' line above.
### END /etc/grub.d/40_custom ###

### BEGIN /etc/grub.d/41_custom ###
if [ -f $prefix/custom.cfg ]; then
source $prefix/custom.cfg;
fi
### END /etc/grub.d/41_custom ###
--------------------------------------------------------------------------------

=============================== sda1/etc/fstab: ================================

--------------------------------------------------------------------------------
# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point> <type> <options> <dump> <pass>
proc /proc proc nodev,noexec,nosuid 0 0
# / was on /dev/sda1 during installation
UUID=c115a6e2-5b2a-4b13-a810-6373cec0e25e / ext4 errors=remount-ro 0 1
# swap was on /dev/sda5 during installation
UUID=b39b8a64-11c5-48f4-a44e-c507334989a1 none swap sw 0 0
--------------------------------------------------------------------------------

=================== sda1: Location of files loaded by Grub: ====================

GiB - GB File Fragment(s)

376.131866455 = 403.868516352 boot/grub/core.img 1
356.174201965 = 382.439137280 boot/grub/grub.cfg 1
1.427730560 = 1.533014016 boot/initrd.img-3.0.0-12-generic 1
1.005863190 = 1.080037376 boot/initrd.img-3.0.0-12-generic-pae 2
356.172374725 = 382.437175296 boot/vmlinuz-3.0.0-12-generic 1
0.700729370 = 0.752402432 boot/vmlinuz-3.0.0-12-generic-pae 2
1.427730560 = 1.533014016 initrd.img 1
356.172374725 = 382.437175296 vmlinuz 1

=============================== StdErr Messages: ===============================

unlzma: Decoder error

[drs305]

volinkov,

The problem most likely is that your Grub files are located on a portion of the drive which can't be seen by BIOS or Grub 2. On many BIOS there is a 137GB limitation on what the BIOS can see. Your Grub 2 files are beyond that limit.

You can check by booting and entering the BIOS setup. Check the reported disk size. If it reports approximately 137 GB, that is the problem. If there is a setting to enable large drives or LBA, enable it. You might also be able to update the BIOS.

If your setup will allow it, shrinking your sda1 partition to approximately 130GB will probably also fix the problem, since it will force the Grub 2 files to be placed within the 137GB limit. If you have to shrink the partition, you will need to use the LiveCD or another 'rescue' type CD since your Ubuntu partition must be unmounted. Gparted is an excellent tool for resizing linux partitions.

The usual caution about backing up critical data files whenever performing partitioning operations.

[volinkov]

I resized the partition and she booted up just fine. Thanks for your help!

[brewmasterkyle]

Help!

I've found that my linux partition is (hd1,1)

I've also found that my grub modules are in (hd1,1)/usr/lib/grub/i386-pc

I then typed


set prefix=(hd1,1)/usr/lib/grub/i386-pc
insmod linux

At which point, it gives me the error:

error: symbol not found: 'grub-mm-base'.

I don't know what to do from here. Please help!!

[drs305]

I've found that my linux partition is (hd1,1)

I've also found that my grub modules are in (hd1,1)/usr/lib/grub/i386-pc

I then typed


set prefix=(hd1,1)/usr/lib/grub/i386-pc
insmod linux

At which point, it gives me the error:

Good for you for being able to locate the modules.

Where you found them is where the originals are stored, but they are the source and are transferred to the boot folder during installation. You might be able to copy them to your /boot/grub folder. I don't know if the installation process does anything more than a direct copy regarding the modules.


You can use the LiveCD to try a direct copy to the mounted grub folder. However, if you use a LiveCD I'd recommend chrooting into your Ubuntu partition and reinstalling Grub 2 completely. I suspect that would be more reliable unless your only problem is missing modules, and nothing else. That is covered in the "Chroot" link in my signature line.

If the modules exist in hd1,1/boot/grub, you can try manually booting with these commands:


ls (hd1,1)/boot/grub
# Do you see the modules? If not, try the alternate module loading command later.
set prefix=(hd1,1)/boot/grub
set root=(hd1,1)
insmod (hd1,1)/boot/grub/linux.mod
# Alternate module load:
# insmod (hd1,1)/usr/lib/grub/i386-pc/linux.mod
# Other modules may be needed as well. Watch for errors when you try to boot.
linux (hd1,1)/vmlinuz root=/dev/sdb1 ro
initrd (hd1,1)/initrd.img
boot

[sprintexec]

'out of disk' can be caused by many things. Often it means the BIOS cannot read the drive. You should probably open up your BIOS setup during boot and check the reported drive size. If the BIOS does not report the full size of your drive, any files physically located beyond the limit seen by the BIOS will not be found.

This little snippet of information was all that I needed to find to get my otherwise no-starting 11.10 installation to boot. I had wondered how it could be that the CD would run perfectly but yet the full install did not.

Thank you DRS305 :guitar:

[drs305]

This little snippet of information was all that I needed to find to get my otherwise no-starting 11.10 installation to boot. I had wondered how it could be that the CD would run perfectly but yet the full install did not.

Thank you DRS305 :guitar:

You are most welcome.

This issue comes up fairly often, especially on older systems.

Even with today's larger drive sizes some relatively recent BIOS's still have the 137GB limit built into them. Presumably because the manufacturers believe that users will only have one OS installed on their computers and the boot files will be very early on the disk.

[c.cobb]

Hi drs305,
I was just going through your nice HowTo making some crib notes when I noticed that you could save a step (and some typing) by omitting the 'iso-scan/filename=' kernel parameter. Without this, the /isodevice directory does not get mounted, and you are left with just the read-only /cdrom mount point -- at least this is how it works when booting 10.04.

Also, for times when you do include the 'iso-scan' param, the file you select can be any existing file on the drive; it doesn't have to be the ISO. A while back I dug down into the lupin-casper shell scripts to see how it worked, because I wanted to have /isodevice mounted when not booting from an ISO file -- again this is on 10.04, so hope it hasn't changed.
Solo mis dos centavos,

[drs305]

Hi drs305,
I was just going through your nice HowTo making some crib notes when I noticed that you could save a step (and some typing) by omitting the 'iso-scan/filename=' kernel parameter. Without this, the /isodevice directory does not get mounted, and you are left with just the read-only /cdrom mount point -- at least this is how it works when booting 10.04.

Also, for times when you do include the 'iso-scan' param, the file you select can be any existing file on the drive; it doesn't have to be the ISO. A while back I dug down into the lupin-casper shell scripts to see how it worked, because I wanted to have /isodevice mounted when not booting from an ISO file -- again this is on 10.04, so hope it hasn't changed.
Solo mis dos centavos,

I appreciate the input. :-)

I've been swamped lately but I'll try to test this in my other releases and update the file.

We struggled with how to set this up before there was any documentation and there are some pretty amusing posts by a group of us scattered around these forums as we tested various ideas. While we got it working, as you discovered there very well can be other and better ways of doing things.

In the meantime, happy holidays and thanks again.

[c.cobb]

Yes, I've followed several of your threads on Grub2, and they've all been very helpful. By coincidence I had a chance to confirm that lupin-casper on Natty (http://packages.ubuntu.com/natty/all/lupin-casper/filelist) still works the same way.

After posting here last night, I tried another of your suggestions (http://ubuntuforums.org/showpost.php?p=11093176&postcount=793) to update Grub2 on a 10.04 install and, in addition to the three packages you mention, it also happened to update lupin-casper. So, this morning I went poking around and, while things have changed some (iirc), the 'iso-scan' mount part works the same.

Thanks and happy holidays to you as well.
Cheers,

p.d. For Natty the pertinent parts are in these two scripts.

/usr/share/initramfs-tools/scripts/casper-premount/20iso_scan
/usr/share/initramfs-tools/scripts/lupin-helpers

[drs305]

c.cobb,

If I remove the isoscan kernel option in the Lucid 10.04 LTS 3 I get a 'Can't open /dev/sr0: No medium found' error message and the system won't boot to the LiveCD Desktop. Here is the menuentry I am using:


menuentry 'ISO Lucid.1 64 ' {
isofile=ubuntu-10.04.3-desktop-amd64.iso
loopback loop (hd1,6)/iso/$isofile
linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=/iso/$isofile noprompt noeject
initrd (loop)/casper/initrd.lz
}

[xanderman]

I am stuck on Step 6 - Load the Linux kernel and initrd image.

The following code:
linux /casper/vmlinuz boot=casper iso-scan/filename=/<ISO-name.iso> noprompt noeject

produces this error:
error: cannot read the Linux header.

PLEASE HELP ME!

[drs305]

xanderman,

Welcome to the Ubuntu forums.

The reference to /casper seems to indicate you are not using a standard installation. 'casper' usually involves trying to boot from an ISO image and not from a installed Ubuntu release.

I would suggest booting a LiveCD and installing the Boot Repair app. It may be able to fix your problem, and if not it will provide an option to run the 'boot info' script, which will provide us with information needed to help you.

You can learn more about the Boot Repair app from its link in my signature line.

[mufler]

Hey guys,

I got into "grub rescue" after trying to reinstall grub2. (I did the reinstall because of dual boot issue when i recently installed window7, in addition to ubuntu 10.04 LTS which was already installed on the netbook)

The error message i get is "error: incompatible licence". And then i am left in the rescue mode. I tried to boot fra a usb stick with ubuntu Live, and guess what. I get prompted with username and password. This has never happend before. Last time I used this LIVE ISO was 2 days ago. The problem is that i just cannot get logged in the LIVE ubuntu. Tried the ubuntu username with blank password. Did ctrl+shift+f1, set password for a user and then alt+f7, but still no go. So here i am stuck.

I have also tried to work inside rescue mode with your advices. I can get into ls (hd0,1)/boot/grub and the .mods are there, but when i type insmod (name of the mod) I get incompatible licence error message. I feel pretty stucked at this stage. I can't execute essential commands in rescue mode, and live iso wont let me in either.

Any suggestions?

[drs305]

mufler,

Welcome to the Ubuntu Forums. I'm out on a business trip and am not logging into the site frequently this week so I'm sorry your post didn't receive a more prompt response.

Normally the 'incompatible license' message means that the core.img that was created when 'grub-install' was created used different modules. Perhaps you were using a newer CD than the one with which you installed Grub originally.

What I would recommend is to boot a LiveCD and purge and reinstall Grub 2. To do this, you have to boot the CD then 'chroot' into your Ubuntu installation. The 'chroot' allows the commands you run on the LiveCD take their action on your real installation.

I don't know how much experience you have, but the instructions on how to do this are in the 'Chroot' link in my signature line. If you have questions, just ask.

[pirog]

Hi guys, drs305!

One of them days I turned off my IBM T23 with a push of a power button because it had froze. Upon restarting it, I was greeted with a blinking cursor and the following message:



error: hd0 read error
grub rescue>_

“ls” gives “(hd0), (hd0,msdos5), (hd0,msdos1) (fd0)”

My guess is that the partition table is intact, hard drive is not dead, grub2 can't see the first block and hence can't boot. I finally logged into LiveCD account (took about 40 minutes with the specs) and tried to mount the drives to save the data. Nautilus didn't show any. Then I remembered (!) that the “/home” partition was encrypted at the install time. BTW it is Mint Katya (11).

Anyways, when in “grub rescue” mode I can't load any modules, heck, I can't list any folders with “
ls (hd0,msdos1)/” (giving me the “error: hd0 read error”) presumably because of encrypted disks. Which btw can't be mounted in the Live-environment.

I am thinking of using LiveCD to re-install grub2 or try to mount encrypted drives through the magic of … hell, I am not too sure how to mount encrypted drives in live-environment. I searched but to no avail. I am not even sure what encryption type is on the HD.

Do you guys have any ideas on the "pickle" of an issue?

Thanks,

p.

[drs305]

Hi guys, drs305!

One of them days I turned off my IBM T23 with a push of a power button because it had froze. Upon restarting it, I was greeted with a blinking cursor and the following message:



error: hd0 read error
grub rescue>_

“ls” gives “(hd0), (hd0,msdos5), (hd0,msdos1) (fd0)”

My guess is that the partition table is intact, hard drive is not dead, grub2 can't see the first block and hence can't boot. I finally logged into LiveCD account (took about 40 minutes with the specs) and tried to mount the drives to save the data. Nautilus didn't show any. Then I remembered (!) that the “/home” partition was encrypted at the install time. BTW it is Mint Katya (11).

Anyways, when in “grub rescue” mode I can't load any modules, heck, I can't list any folders with “
ls (hd0,msdos1)/” (giving me the “error: hd0 read error”) presumably because of encrypted disks. Which btw can't be mounted in the Live-environment.

I am thinking of using LiveCD to re-install grub2 or try to mount encrypted drives through the magic of … hell, I am not too sure how to mount encrypted drives in live-environment. I searched but to no avail. I am not even sure what encryption type is on the HD.

Do you guys have any ideas on the "pickle" of an issue?

Thanks,

p.

Hey pirog,

I'm going to be pretty scarce on the forums for the next month and a half. I don't have a ready answer for you as I'm not educated on all the aspects of encrypted drives. Some of the things I'd recommend wouldn't work because of the encryption.

What I'd recommend for now is to start your own thread and describe your situation. There are a lot of bright people on this forum and some understand and use encryption. Mention that the partition is encrypted in the thread title so you get the attention of users who can help you. The good news is that your /home partition doesn't come into play during the initial part of the boot process so you might be able to fix things even with the encrypted home partition.

I'd suggest running the boot info script. The script generates a file called RESULTS.txt which provides a lot of information about the status of your boot files. It can be run from a LiveCD, as can the tool mentioned next.

You can try to fix things with the Boot Repair tool. If it can't help, it would at least provide the option to run the boot info script for you. You can learn more about Boot Repair from the link in my signature line. (Also BIS)

Best of luck. If I'm on the forums I'll check for your new thread and offer any help I can.

[pirog]

Hey pirog,

I'm going to be pretty scarce on the forums for the next month and a half. I don't have a ready answer for you as I'm not educated on all the aspects of encrypted drives. Some of the things I'd recommend wouldn't work because of the encryption.

What I'd recommend for now is to start your own thread and describe your situation. There are a lot of bright people on this forum and some understand and use encryption. Mention that the partition is encrypted in the thread title so you get the attention of users who can help you. The good news is that your /home partition doesn't come into play during the initial part of the boot process so you might be able to fix things even with the encrypted home partition.

I'd suggest running the boot info script. The script generates a file called RESULTS.txt which provides a lot of information about the status of your boot files. It can be run from a LiveCD, as can the tool mentioned next.

You can try to fix things with the Boot Repair tool. If it can't help, it would at least provide the option to run the boot info script for you. You can learn more about Boot Repair from the link in my signature line. (Also BIS)

Best of luck. If I'm on the forums I'll check for your new thread and offer any help I can.

Hi drs305,

Thanks for the tips. You are certainly right in that I start a new thread, but I thought it would be a good place to start my search. I was hoping you had had a similar problem, since yours is related to mine.

I'll give the script a try and if anything good comes of it, I'll let you know. The thing about “/home” partition, you are right it won't come into play until later. I still think it is the grub2 issue. If I ever get to solve this problem, I'll write it up in a new post for others to see.

Thanks for your suggestions mate.

Regards,

p.

[HotForLinux]

How can I work with grub2's command line inside Ubuntu?




If you don't find the modules, try the alternate location: ls (hdX,Y)/usr/lib/grub/i386-pc

In my case one location has 204 modules and the other 207 with only 9 differences is that normal? I thought that duplicate info was a sin.

It suddenly reminded me the disorder in *******'s directories.

[drs305]

How can I work with grub2's command line inside Ubuntu?




If you don't find the modules, try the alternate location: ls (hdX,Y)/usr/lib/grub/i386-pc

In my case one location has 204 modules and the other 207 with only 9 differences is that normal? I thought that duplicate info was a sin.

It suddenly reminded me the disorder in *******'s directories.

I've never closely inspected/compared the two folders, but I know that the grub folder used for booting contains at least a couple of files that are generated 'locally' - grub.cfg (the menu) and grubenv. I'm sure there are several others as well, which would explain the differences.

[HotForLinux]

183 files!:
sun@milkyway:~$ for i in /boot/grub/*.mod; do cmp "/usr/lib/grub/i386-pc/$(basename $i)" "$i"; done

the differences:
sun@milkyway:~$ for i in /boot/grub/*; do cmp "/usr/lib/grub/i386-pc/$(basename $i)" "$i"; done
sun@milkyway:~$ for i in /usr/lib/grub/i386-pc/*; do cmp "/boot/grub/$(basename $i)" "$i"; done

the links:
?

who knows... ?

[rajarjun]

i have installed ubuntu inside windows and then afterwords i installed fedora 16...all time during start up its show os selection by grub loader but after i did some partition on windows its shows error:unknown filesystem.enterting rescue mode.. grub rescue>

grub rescue>ls
(hd0)(hd0,msdos9)(hd0,msdos8)(hd0,msdos7)(hd0,msdo s6)(hd0,msdos5)(hd0,msdos3)(hd0,msdos2)(hd0,msdos1 )
and then i found out content of partition root as u told..
grub rescue>ls (hd0,msdos7)/
./ ../ lost+found/ etc/ dev/ boot/ var/ sys/ proc/ lib64/ usr/ bin/ home/ lib/ media/ mnt/ opt/ root / run/ sbin/srv/ tmp/ .readahesd
grub rescue>ls (hd0,msdos7)/boot/grub
./ ../ splash.xmp.gz
grub rescue>set prefix=(hd0,msdos7)/boot/grub
and then if i give all load module command it says error:file not found.
what i can do now any body help this hoping for correct solution

[drs305]

what i can do now any body help this hoping for correct solution

Welcome to the Ubuntu Forums. :-)

It looks like you have done a good job of troubleshooting. I don't use Wubi so I'm not comfortable giving advice about it. I believe with Wubi you should still see the Windows bootloader first; if Grub was installed in the MBR you would most likely have lost both the Windows bootloader and also not be able to boot from Grub.

There is an excellent GUI app called Boot Repair but I don't know if it works with Wubi. I think it can and if you have lost your Windows bootloader it probably has an option to restore it via a bootloader called lilo.

Even if BR can't repair your system, it has an option to run the boot info script which can help find out what is happening. There is a link to Boot Repair in my signature line.

Another good resource is the Wubi Megathread, which specializes in Wubi installations:
http://ubuntuforums.org/showthread.php?t=1639198

[mkalioby]

Thanks, you have recused me

[jpascua]

Load the modules.

set prefix=(hdX,Y)/<path to modules>
This command must correctly point to the folder containing the Grub modules. The address should be the one in the previous section which displayed the modules.
Examples:
set prefix=(hd0,5)/boot/grub
set prefix=(hd1,1)/usr/lib/grub/i386-pc

Load modules:


insmod linux
insmod loopback
insmod iso9660
insmod fat # If ISO is located on fat16 or fat32 formatted partition.
insmod ntfs # If ISO is located on an NTFS formatted partition.
insmod nftscomp # If NTFS compression is used on the partition. Load if you aren't sure.


A "file not found" error means that the path in the prefix is incorrect or the specific module does not exist. The prefix setting may be reviewed with the set command. Rerun the "set prefix=" command with the proper path.



So I have gotten to this step but when I do the set prefix= command it does nothing... How can I change that??