GRUB 2 - A Guide for Users

8/6/2019 GRUB 2 - A Guide for Users

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GRUB 2 A Guide for Users

Updated: 9/11/09, 9/12/09, 9/20/09, 9/22/09, 9/23/09, 10/04/09, 10/6/09, 10/7/09, 10/9/09, 10/12/09 (Dual

booting, drivemap in Reply #1), 12/4/09 (edited References)

Bugs and Questions: See REFERENCES at the end.

In Progress -- pending the completion of the GRUB 2 Manual: http://grub.enbug.org/Manual.

GRUB 2 Practical Reminders (a cheat sheet for those who know what they are doing)See end of SECTION 4 Special Topics.

Installing Kubuntu--GRUB 2 placement

Telling the Live CD installer where to put GRUB 2

-> See the Appendix

New:

Booting Windows XP on a non-first hard drive

See Reply #1

NEW Notes about some of the new GRUB 2 commands: See Reply #1

NEW comment (10-0-09)

update-grub vs grub-mkconfig

It appears that update-grub has been replaced by grub-mkconfig.

HOWEVER, it appears that update-grub works fine, at least in 9.10 Karmic.

update-grub is usually easier to use.

(To Do: Track the status of this)

I have made the switch throughout the how-to (in the first post of this thread).

Note: update-grub

The command update-grub generates a new grub.cfg file and replaces the existing grub.cfg with the newly

generated grub.cfg (by default).

But, as explained next, you must specify the output file when using grub-mkconfig:Note that

sudo grub-mkconfig

prints its output to the screen (default = stdout).

To print to the grub.cfg, use

sudo grub-mkconfig -o /boot/grub/grub.cfg

or

sudo grub-mkconfig --output=/boot/grub/grub.cfg

- - - - - - - - - -

TABLE of CONTENTS

SECTION 1

Introduction

History: GRUB Legacy, GRUB 2

Differences between GRUB Legacy and GRUB 2

GRUB 2 commands

Notes about some of the new GRUB 2 commands: See Reply #1

SECTION 2

Key Facts About the Boot menu, grub.cfg

Quick version -- Overview -- Details

/etc/grub/default --> /etc/grub.d --> /boot/grub/menu.lst


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Rules for editing grub.cfg, /etc/default/grub, and the script files in /etc/grub.d

GRUB 2 device numbering is different: Partitions start at 1

Details

SECTION 3 Fixing Things

A checklist of things to try to fix a broken system

A Troubleshooting Outline

Ctrl+Alt+Del will reboot your PC

Super Grub Disk: Very Important

Key commands: grub-mkconfig and sudo grub-installTimeout & Default OS, changing

Kernel options, changing

To see or to hide the boot menu

Missing OS entry in the boot menu

Editing the boot menu during booting: "e" key

The GRUB prompt grub> -- What to do with it

=> Getting information and booting an OS

Re-installing GRUB 2 using Live CD: Key Rescue Method

Using a Live CD to edit files in your OS

SECTION 4

Special TopicsInstalling GRUB 2 to your PC

grub-install The most useful command

The various types of command modes.

"c," grub>, Konsole BASH, edit "e", emu

TAB Completion

How to get information about your drives and devices

At Konsole : sudo fdisk -lu

At the GRUB 2 prompt: grub> ls

Boot menu: Adding or removing an OS entry

Boot menu: Create a custom boot entry

Boot menu: Making your own custom grub.cfg

Boot menu: Changing resolution, text colors, setting background image4 ways to boot an OS: configfile, symlinks, direct booting, chainloader

Boot menu: Background image editing tip for those with widescreen monitors

Dedicated GRUB 2 partition: How to build it

GRUB 2 Flashdrive: How to build it

Use of the term "root"

GRUB's Root Device, the Linux statement: root=UUID=,

--root-directory=DIR INSTALL_DEVICE

Dual booting: See Reply #1

Booting XP on a non-first hard drive (drivemap): See Reply #1

Cheat sheet: GRUB 2 Practical Reminders

Appendix: Techniques

--- Installing Kubuntu--GRUB 2 placement

--- Working as root, editing a file

--- Permissions: read, write, execute; change the execute bit

--- Chroot -- how to

References and Tutorials

See also REPLY #1 below this post for more GRUB 2 topics:


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Notes about some of the new GRUB 2 commands

Included: chainloader, ls, grub-emu, grub-mkconfig (many tips!), root, rootnoverify (is gone), grub-setup

grub-install: See SECTION 4 above.

drivemap: See Reply #17 below; See Reply #1

loopback: See Boot From ISO (below)

Dual booting: How to set it up

Installing two or more Linux operating systems

RECOMMENDED METHOD

PROBLEMSMessing up the booting -- fixing GRUB without re-installing Kubuntu

Windows topics

Installing XP (or 7? or Vista?) & Kubuntu:

How to set up dual booting (recommended outline)

Re-installed XP and now can't boot Kubuntu

XP on a non-first hard drive: (hdx,y), x > 1

Booting XP on a non-first hard drive

The drivemap command in GRUB 2

Boot From ISO -- use of GRUB 2 loopback

Boot your Kubuntu Live CD ISO from your flashdrive

GPT: GUID Partition Table

... for Kubuntu 9.10 and GRUB 2

=> Overcoming the "2 TB disk size limit"associated with the conventional MBR

=> Testing GRUB 2 on your GPT-partitioned flash drive

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SECTION 1

Introduction

History: GRUB Legacy, GRUB 2Differences between GRUB Legacy and GRUB 2

GRUB 2 commands


History: GRUB Legacy, GRUB 2

"Briefly, boot loaderis the first software program that runs when a computer starts. It is responsible for loading and

transferring control to the operating system kernel software (such as the Hurd or the Linux). The kernel, in turn,

initializes the rest of the operating system (e.g. GNU)." (gnu.org)

The original GRUB (GRand Unified Bootloader) was developed by Erich Stefan Boleyn, from which came the GRUB

most of us know, GRUB version 0.9x, and that is now referred to as GRUB Legacy (or even GRUB 1 by some writers).GRUB 2 replaces GRUB Legacy. (GRUB 2 is actually the end result of versions GRUB 1.xx; e.g., 1,96, 1.97, ...)

For the history of GRUB and some interesting links, see

http://www.gnu.org/software/grub/

GRUB 2 is cleaner, more efficient, powerful, and more elegant, in many ways it is simpler to use than GRUB Legacy.

GRUB 2: http://www.gnu.org/software/grub/grub-2.en.html

Its mailing list for development,

GRUB-devel: http://lists.gnu.org/mailman/listinfo/grub-devel

And the Wiki: http://grub.enbug.org/


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GRUB 2 is the default bootloader in 9.10

https://lists.ubuntu.com/archives/ubuntu-devel-announce/2009-June/000573.html

Differences between GRUB Legacy and GRUB 2

From the user's view, the biggest difference between the two versions of GRUB concerns the boot menu

configuration file.

GRUB 2: /boot/grub/grub.cfg

GRUB Legacy: /boot/grub/menu.lstThe configuration file is used to generate the boot menu you see at boot time.

In GRUB Legacy, you can edit menu.lst directly and in any way you wish.

In GRUB 2, you should not edit grub.cfg directly. Instead, you edit the file /etc/default/grub (which contains some

default settings); this file feeds data to scripts in the folder /etc/grub.d. And you may edit the scripts (text files) in

the folder /etc/grub.d; these scripts are used to generate the configuration file /boot/grub/grub.cfg. When you

need a new grub.cfg, simply do sudo grub-mkconfig -o /boot/grub/grub.cfg.

It is conceptually simple in GRUB 2:

You can edit the file /etc/default/grub and you can edit the scripts in /etc/grub.d, then run the command sudo grub-

mkconfig -o /boot/grub/grub.cfg, and the file grub.cfg is automatically generated.

The configuration file in GRUB 2 grub.cfg looks different than the GRUB Legacy menu.lst. For example, in GRUBlegacy, you use

default 0

timeout 5

In GRUB 2, default and timeout are variables, and it is

set default=0

set timeout=5

A boot entry in GRUB Legacy menu.lst might look like this:

title Ubuntu 8.04.3 LTS, kernel 2.6.24-24-generic

root (hd1,2)

kernel /boot/vmlinuz-2.6.24-24-generic root=UUID=0df17bc5-0056-4ef7-bfca-251194b6eb44 ro quiet splash

initrd /boot/initrd.img-2.6.24-24-generic

In GRUB 2 grub.cfg, it would look like this:

### BEGIN /etc/grub.d/10_Linux ###

menuentry "Ubuntu 8.04.3 LTS, kernel 2.6.24-24-generic" {

set root=(hd1,2)

linux /boot/vmlinuz-2.6.24-24-generic root=UUID=0df17bc5-0056-4ef7-bfca-251194b6eb44 ro quiet splash

initrd /boot/initrd.img-2.6.24-24-generic

}

### END /etc/grub.d/10_Linux ###

Note how the title line is changed in GRUB 2: Use menuentry instead, put the text in quotes, and start the bootentry with a left brace {, ending it with a right brace }. Instead of kernel, the word linux is used; initrd is the same.

Instead of root=, in GRUB 2 it is set root= (in GRUB 2, root is a variable).

sudo grub does not get you a GRUB 2 shell at Konsole

In GRUB Legacy, the user may open a GRUB shell by typing sudo grub, and then use it to install/re-install GRUB (root-

setup-quit) to a Master Boot Record or to a partition boot sector. In GRUB 2, there is no such option. Instead, the

key command is the Konsole (BASH) command grub-install. At Konsole, as root, you will use sudo grub-install to

install/re-install GRUB 2 to a Master Boot Record or to a partition boot sector.

Device names have changed. In GRUB Legacy, the numbering of both hard drives and partitions start at zero.

(hd0,0) is the first hard drive (hd0), the first partition (partition zero). In GRUB 2, the numbering of hard drives also


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starts at zero: hd0 is the first hard drive. But partition numbering starts at 1: (hd0,1) is the first hard drive, the first

partition (partition one).

In GRUB Legacy, we use the find command; e.g., grub>find /boot/grub/menu.lst. In GRUB 2, the search command

replaces the find command: grub>search /boot/grub/grub.cfg.

In GRUB Legacy, the geometry command (at the grub> prompt) is very useful for listing devices as GRUB sees them

on your PC. It is not used in GRUB 2. Instead the list command ls (at the grub> prompt) replaces the geometry

command.

GRUB Legacy uses stages: stage_1, stage_1.5, and stage_2. Those are replaced in GRUB 2 by boot.img (a 512-byte

file that corresponds to stage_1 and is installed to a MBR); there is no stage_1.5 in GRUB 2; and core.img in GRUB 2

takes the place of stage_2 (or, perhaps, of both stage 1.5 and stage_2). Details: See Section 4 the subsection "grub-

install: A key command."

GRUB 2 Commands -- compared to GRUB Legacy

Comparison chart:

http://grub.enbug.org/CommandList

Key useful items to note:

GRUB Legacy GRUB 2

find is replaced with search

geometry is gone and replaced by ls

kernel (in menu.lst) is replaced by linux (and other terms for different OSs)

title (in menu.lst) is replaced by menuentry (in grub.cfg)

root is still used but is now a variable

setup is gone; the work is done by grub-install

map is replaced by drivemap

device is replaced by loopback (makes a drive out of a file)

set is a GRUB 2 term used to set a variable


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SECTION 2 Key Facts About the Boot menu, grub.cfg

Quick version -- Overview -- Details

/etc/grub/default --> /etc/grub.d --> /boot/grub/menu.lst

Rules for editing grub.cfg, /etc/default/grub, and the script files in /etc/grub.d

GRUB 2 device numbering is different: Partitions start at 1

Details

Quick version:/etc/grub/default --> /etc/grub.d --> /boot/grub/menu.lst

Rules:

-- The file /boot/grub/grub/cfg generates the boot menu.

-- Do not directly edit /boot/grub/grub/cfg.

-- You may edit (as root) /etc/default/grub.

(timeout, default OS, kernel options, resolution of the boot menu)

-- You may edit (as root) the scripts in /etc/grub.d.

-- Together, /etc/default/grub and the scripts in /etc/grub.d generate /boot/grub/grub.cfg.

-- To create a script, start with a text file as root: kdesudo kate

-- To makefilename executable: sudo chmod 744 /etc/grub.d/filename

or, sudo chmod +x /etc/grub.d/filename


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-- To remove execute permission fromfilename: sudo chmod -x /etc/grub.d/filename

-- To open Konqueror (Dolphin) as root: kdesudo konqueror

-- Generate a new configuration file /boot/grub/grub.cfg after editing /etc/default/grub and after editing, creating,

or deleting scripts in /etc/grub.d, as follows:


Examples of grub.cfg

http://svn.savannah.gnu.org/viewvc/trunk/grub2/docs/grub.cfg?root=grub&view=markup

Or: /usr/share/doc/grub-pc/examples/grub.cfg.

Also: http://grub.enbug.org/grub.cfgAlso: GRUB 2 Basics http://ubuntuforums.org/showthread.php?t=1195275

GRUB 2 device numbering is new: Partitions y start at 1

In GRUB 2 (as in GRUB Legacy), hard drives start at zero: hd0 is the first hard drive. In GRUB 2 (unlike GRUB Legacy),

partition numbering starts at 1: (hd0,1) is the first partition in the first hard drive; (hd0,2) is the second partition in

the first hard drive; (hd1,2) is the second partition in the second hard drive.

Linux device notation is the same as in GRUB Legacy

sda is the first hard drive; sdb is the second hard drive; sdc is the third; etc.

sda1 is the first partition of the first hard drive; sda2 is the second partition of the first hard drive; etc.

Details

The configuration file is called /boot/grub/grub.cfg, and it generates the boot menu you see on your screen when

you boot your PC (and so, /boot/grub/grub.cfg can be called the boot menu configuration file). You are NOT

supposed to edit it (it is read-only). It is generated from a folder of scripts called /etc/grub.d. Another key file is

/etc/grub/default and it feeds default data to the scripts in /etc/grub.d. You may edit /etc/grub/default (as root).

You may also edit the scripts in /etc/grub.d (as root). If you create a new file in /etc/grub.d, you must make it

executable if you want the entry included in the configuration file grub.cfg. If you do not want a script to execute

(and so remove that entry from grub.cfg), you must remove the execute bit (i.e., remove the execute permission).

>>> Key reminder:

Generate a new grub.cfg after changing anything in /etc/default/grub or /etc/grub.d by:grub-mkconfig -o /boot/grub/grub.cfg

Experts: Editing grub.cfg

The file is read-only, so change permission to include Write:

sudo chmod +w /boot/grub/grub.cfg

Then do the edits as root and Save. When grub-mkconfig is run, the file returns to read-only (chmod 444 or 400),

AND your edits may be overwritten (and therefore gone).

Optional: After editing, restore permissions to disallow writing:

sudo chmod -w /boot/grub/grub.cfg or

sudo chmod 444 /boot/grub/grub.cfg

The default settings file /etc/grub/default

This file feeds data to the scripts in /etc/grub.d. It contains the Default operating system, the Timeout, kernel

options, resolution of the graphical boot menu, and other default settings. You may edit this file with root privileges.

The folder of scripts /etc/grub.d

These scripts generate /boot/grub/grub.cfg when the grub-mkconfig command is run (as root). The order of the

entries in grub.cfg corresponds to the order of the files in /etc/grub.d, starting with 00_header, then 01_scriptname,

etc., through all files starting with NN_ where NN is a 2-digit number and _ is the underscore (Shift+(minus sign));

then comes scripts whose names start with a letter (e.g., a_anotherscript).

You may edit the script files (as root) or create new ones. To create a new entry in grub.cfg, you simply create a new


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script file: a text file that you make executable (like a program). To remove an entry from grub.cfg, remove the

execute permission from the corresponding script file in /etc/grub.d. (If the entry corresponds to a custom script

you wrote, you may also delete that script file from /etc/grub.d).

See SECTION 4 Special Topics -- Create a custom boot entry.

Editing the script files in /etc/grub.d:

Do your work as root.

To make the file /etc/grub.d/filename executable:

sudo chmod 744 /etc/grub.d/filename

To remove the execute bit from the filefilename:sudo chmod -x /etc/grub.d/filename

When done, run


to generate a new boot menu configuration file /boot/grub/grub.cfg.

GUI: How to set permissions

Open Konqueror or Dolphin as root (e.g., kdesudo konqueror).

Open the file.

Right-click > Properties > Permissions, Advanced Permissions

Tip: To open a file in /etc/grub.d (as root)

The files in /etc/grub.d are scripts. So, as root, if you click on one, it will want to execute or run like a program.

Instead, to open a script for editing/viewing, right-click on the script file, Open With Kate or Kwrite. That opens thefile as a text file. Now you can read it or edit it.

Details:

GUI, working as root: Open Konqueror (Dolphin) as root and work from there:

kdesudo konqueror

CLI, working as root: kdesudo kate /etc/grub.d/script_name

Quick reference

The (standard) files in /etc/grub.d (each is a script) are:

00_header

05_debian_theme: Set background, text colors, themes

10_hurd Locates Hurd kernels10_linux Locates Linux kernels based on results of the lsb_release command.

The target are kernels located on the same partition as the root partition

of the current OS you are in (where this grub.cfg is located).

In contrast to: 30_os-prober (see below)

20_memtest86+: If the file /boot/memtest86+.bin exists, it is included in the boot menu.

30_os-prober: Searches for Linux and otherOS's on allpartitions; includes them in the boot menu.

40_custom: A template for adding custom boot menu entries.

See Appendix: permissions, working as root, making a file executable, Konsole, and other topics.

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SECTION 3 Fixing Things

A checklist of things to try to fix a broken system

A Troubleshooting Outline



Key commands: grub-mkconfig and sudo grub-install

Timeout & Default OS, changing





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Editing the boot menu during booting: "e" key



Re-installing GRUB 2 using Live CD: A Key rescure method


Troubleshooting Outline

When you can't boot into your OS, there are two possible causes:the boot menu is flawed, and/or

the GRUB 2 installation is flawed.

To fix it, you have two choices:

boot into the OS somehow and fix it;

or

fix it from outside the OS (e.g., live CD, another OS, or live flash drive).

Before looking at these two choices, note two important things:

> To fix the boot menu means to fix its configuration file /boot/grub/grub.cfg. You can sometimes do that

temporarily using the edit-on-the-fly "e" key (see subsection below). To fix it permanently, you do NOT edit grub.cfg

directly; but rather you edit the file /etc/default/grub and/or you edit the script(s) in /etc/grub.d, and then you usethe command grub-mkconfig to generate a new grub.cfg.

> To fix the GRUB 2 installation, that usually means re-installing GRUB 2 using, at Konsole, the command grub-

install. You can do this from inside the OS (if you can boot into it somehow), or from a Live Kubuntu CD or from

another Linux OS on your hard drive. You cannot do it from the GRUB 2 prompt (grub>) when booting the PC. (In

GRUB Legacy, you could do it by getting the grub> prompt and using the root and setup commands.)

Now let's look at each of your two choices for fixing the problem.

--> How to boot into your OS when you can't seem to boot into your OS:

(1) SGD, or (2) use the grub>, or (3) use the "e" key.

Some tips and details:

> Use Super Grub Disk to boot into it. You may have SGD fix the boot (under GNU/Linux options), or simply use SGD

to boot the OS so you can get into it. If you use SGD to fix the boot, it will re-install GRUB to your drive, so make sure

that's what you want; also, it may do so using either GRUB Legacy or GRUB 2, depending on the SGD CD version you

are using. Of course, if you can get booted into the OS, then you can fix anything and everything, so maybe you

won't be feeling too picky at this point.

Note: Along these lines, you can also use your own GRUB 2 disk/flashdrive to boot your OS, if you built one.

> Boot into your OS yourself, manually, using the GRUB 2 prompt, grub>, ASSUMING you can get the prompt!

(Sometimes, you can't.) See the Subsection below titled "The GRUB prompt grub> -- What to do with it."

> Boot into your OS yourself by fixing the boot menu (editing it "on-the-fly" using the "e" key when you see it on the

screen). But sometimes, you don't see the boot menu. See the Subsection below titled "Editing the boot menuduring booting: 'e' key" If you are successful, since these "e" edits are only temporary, after booting into the OS, you

must make the changes permanent (by editing /etc/default/grub or the script(s) in /etc/grub.d and then generate a

new grub.cfg using grub-mkconfig -o /boot/grub/grub.cfg.

--> How to fix the problem from outside the OS:

(1) Use a Live CD, or (2) Fix it from another OS.

Some details:

> Use a Live CD.

From a Live Kubuntu CD (or most any live Linux CD), you can re-install GRUB and/or perform edits on files


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(/etc/default/grub or the script(s) in /etc/grub.d). See the subsections below: "Re-installing GRUB 2 using Live CD:

Key Rescue Method" and "Using a Live CD to edit files in your OS."

> Fix the problem from another Linux OS, ASSUMING you are able to boot into one!

From there, you can edit files in your broken OS and/or re-install GRUB 2 using grub-install.

(NOTE: From the second OS, or even from a Live CD, you'd have to mount the broken OS partition; or perhaps

looking in your file manager you'd see it is automatically mounted for you.)

[End of Troubleshooting Outline]


If your PC freezes up during the experiments/testing/troubleshooting of your bootloader, use Ctrl+Alt+Del to re-

boot the PC. Be prepared to do something, though!

Examples of what to do:

-- Before using Ctrl+Alt+Del, put the Super Grub Disk CD in the CD tray so you can re-boot to it and rescue your OS.

-- Be prepared to press the key required to enter your BIOS setup. That will buy you some time, or give you a

chance to change hard drive booting order, or put a live CD or SGD in the CD tray, or get your notes ready, etc.

-- If you have been getting a boot menu, let the PC reboot into it, then enter Edit mode (pressing the "e" key) or

enter the GRUB 2 CLI (pressing the key "c"), then try to fix things from there.


Whether you think you need it or not, get it now, free, as a bootable CD which will get you booted into your

operating system in case you can't. SGD can be downloaded here: http://www.supergrubdisk.org/ . Look for a CD

ROM iso version, download it, burn it as an iso image to a CD (using K3b), test it briefly (by running it and stepping

through a few menus but not choosing anything; then Quit; or, use it to boot into your OS).

Tip (using SGD to boot into your broken OS)

Choose GNU/Linux > Fix Boot, then select the broken partition.

Should you decide to simply Quit the SGD (without doing anything), do so, select reboot, enter your BIOS setup,

remove the SGD CD, exit BIOS, and continue rebooting.

Key commands: sudo grub-mkconfig and sudo grub-install

Use these two commands to "freshen up" your GRUB 2 installation.

grub-mkconfig: builds a new boot menu configuration file boot/grub/grub.cfg.

grub-install: builds a complete, fresh GRUB 2 installation, including /boot/grub/grub.cfg.

grub-mkconfig

will generate a new boot menu /boot/grub/grub.cfg. To do so, it uses /etc/default/grub and the scripts in

/etc/grub.d. You should run this command after editing the default file or the scripts:


or

sudo grub-mkconfig --output= /boot/grub/grub.cfgSee Reply #1 (to this post): Notes about some of the new GRUB 2 commands

sudo grub-install [INSTALL_ DEVICE]

installs or re-installs GRUB 2 to INSTALL_DEVICE.

See SECTION 4: grub-install: A key command

For now, here's some highlights.

sudo grub-install /dev/sda

installs GRUB 2 to the Master Boot Record of drive sda. And

sudo grub-install /dev/sda1


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installs GRUB 2 to the boot sector of the partition sda1.

In doing so, grub-install does a complete job of setting up everything.

Here's what it does: It builds the directory /boot/grub (if it doesn't already exit), copies GRUB 2 files to it from the

"master" image directory /usr/lib/grub/i386-pc, probes your drives and devices and partition table, makes a new

device.map, builds and installs boot.img (to MBR) and core.img, and builds /boot/grub/grub.cfg.

> Man page: (8)GRUB-INSTALL - Install GRUB on your drive.

http://grub.enbug.org/FranklinPiat/grub-install.manpage

Troubleshooting-- After running grub-mkconfig, make sure that the line set default=(hdx,y) is correct (i.e., that the order of the

menuentries did not change the default OS position).

-- sudo grub-install --recheck [INSTALL_DEVICE]

=> If you get an error running sudo grub-install, try it again with sudo grub-install --recheck [INSTALL_DEVICE].

Timeout and Default OS, changing

The timeout is the length of time in seconds before the (highlighted) default OS is automatically booted (if you do

not intervene by touching a key). To change these values, open the file /etc/default/grub as root, make the changes,

Save, exit, then generate a new /boot/grub/grub.cfg by running sudo grub-mkconfig -o /boot/grub/grub.cfg.

Opening /etc/default/grub as rootIf your file manager supports it, open the file manager, navigate to /etc/default/grub, right-click on the file, Actions,

Edit as Root. Otherwise:

Open the file manager as root and work from there:

kdesudo konqueror

kdesudo dolphin

Or, open the file as root using Kate or Kwrite:

kdesudo kate /etc/default/grub

Example

GRUB_DEFAULT=0

GRUB_TIMEOUT=5

GRUB_DEFAULT=0 selects boot entry #0 (i.e., the first entry) as the default OS to be booted automatically. Boot

entries can be seen in your /boot/grub/grub.cfg file; they start with a line

menuentry "some descriptive text" {

and end with

}

Boot entries are counted from zero; so the first menuentry is boot entry #0, the second menuentry is boot entry #1,

etc.

Troubleshooting Tip: Check default OS setting after grub-mkconfig

If you recently added/removed a boot entry (by editing a /etc/grub.d script) and ran grub-mkconfig to generate a

new boot menu, you might have to check and edit the line "GRUB_DEFAULT= " (in /etc/default/grub) if the defaultsequence number changed.

(TO DO: Check also: sudo grub-set-default N.)


To change these values, open the file /etc/default/grub as root, make the changes, Save, exit. (See Timeout and

Default OS above for editing tips.) The line in /etc/default/grub looks like this (or similar):

GRUB_CMDLINE_LINUX="quiet splash"


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Look for this line in the file /etc/default/grub:

# GRUB_HIDDEN_TIMEOUT=0

With the # sign present, you will see the boot menu upon booting your PC.

With the # removed, you will not see the boot menu.

For a detailed explanation of the other ways this works, see

GRUB 2 Basics drs305

http://ubuntuforums.org/showthread.php?t=1195275


If you run grub-mkconfig, and there is a missing entry in your boot menu, you can add that entry as a custom entry.

See SECTION 4 below, Special Topics Boot menu: Create a custom boot entry.

Editing the boot menu during booting using the "e" key

When you boot/re-boot your PC, the boot menu appears. If you select an entry (an OS to boot into) and get an

error, and if you are able to return to the boot menu (or re-boot again to get it), you may be able to fix things or to

experiment with your boot menu to see if something will work. See the help tips at the bottom of the boot menu.

At the boot menu, highlight an entry, press the "e" key, and you'll see the menuentry statements for that OS. Seethe help tips at the bottom of that menu. If you highlight a line, press the "e" key, that line will be displayed so you

can edit it (using arrow keys, delete, etc.). Pressing ESC returns you to the previous screen.

The edits you make to the boot menu are "on-the-fly" edits and are not permanent. To make them permanent,

you'll have to edit /etc/default/grub and/or the script files in /etc/grub.d, perhaps even making a custom boot entry

if necessary (SECTION 4 Special Topics Boot menu: Create a custom boot entry), then generate a new

/boot/grub/grub.cfg file using grub-mkconfig.



You may get the GRUB prompt grub> in three ways:

> "c" key: You re-boot and upon seeing the boot menu, press the "c" key to get the grub>. (Or Control+c at the

Edit mode menu.) (By pressing the ESC key, you get back to the boot menu.)

Or:

> No boot menu! Perhaps, you re-booted your PC and didn't see any boot menu but instead got dropped to the

GRUB 2 prompt: grub>.

Or:

> You get a grub> when re-booting using your own GRUB 2 flash drive (which is what is usually supposed to

happen!).

From the grub> prompt, you may be able to issue commands tohelp you gather information about your drives

or

boot your computer.

Use these resources:

SECTION 4 Special Topics, the subsection

"4 ways to boot an OS" -- direct booting configfile, symlinks, chainloader

SECTION 4 Special Topics, the subsection

"How to get information about your drives and devices"

=> In particular, take special note of the ls command and the use of TAB completion.


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Re-installing GRUB 2 using Live CD: Key Rescue Method

There are two main ways of doing this: By chrooting into the broken partition and by not chrooting. For the

chrooting way, see GRUB 2 Live CD Install Guide: http://grub.enbug.org/Grub2LiveCdInstallGuide For details about

chrooting, see the Appendix in the first post (above).

For "my" way, I'll call "Method 1," of re-installing GRUB2 from a live CD, read on.

Method 1: Installing or re-installing GRUB 2 using a Live CD

Your Kubuntu Live CD contains GRUB 2 files; specifically, in a live session, you will find the master GRUB 2 "image"

files in /usr/lib/grub/i386-pc. Thus, they can be used to install or re-install GRUB 2. Here's how ...

Start your Kubuntu Live CD.

Choose the option to try Kubuntu without installing.

Open Konsole (Terminal): K-Menu > System > Konsole

Explore your partitions using

sudo fdisk -lu

Determine your root partition. In this example, ours is sda2.

Make a mount point (directory) for partition sda2:

sudo mkdir /media/sda2Mount sda2 on the mount point:

sudo mount /dev/sda2 /media/sda2

Make a mount point (directory) for /dev:

sudo mkdir /media/dev

Mount the devices in your Live CD session:

sudo mount --bind /dev /media/dev

Install (or re-install) GRUB 2 (into the MBR of drive sda) using the GRUB 2 files in sda2:

sudo grub-install --root-directory=/media/sda2 /dev/sda

You may get this error:

grub-probe: error: Cannot find a GRUB drive for /dev/sda2. Check your device.map.

Auto-detection of a filesystem module failed.Please specify the module with the option `--modules' explicitly.

If so, try this:

sudo grub-install --recheck --root-directory=/media/sda2 /dev/sda

Maybe you'll get lucky and see this:

Installation finished. No error reported.

This is the contents of the device map /media/sda2/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

(=> and so this was successful)

Then, unmount both filesystems:

sudo umount /dev/sda2 /media/sda2

sudo umount /dev /media/dev

Leave Konsole:

exit

Test it:

Exit out of the Live CD, reboot, see if you fixed your booting problem (by booting into the broken partition).

[End of Method 1]

- - - - - - - - - -


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This is done as you would normally do it. Of course, if you wish, you may use Super Grub Disk to boot into your OS

and do the editing from there. Here is an outline of a standard way to use your Kubuntu Live CD.

Boot the Live Kubuntu CD, open Konsole, then as root make a directory, mount the filesystem containing the file you

need to edit, open that file (possibly as root), edit it, save, quit, unmount the filesystem, exit.

Example

If the file you need to edit is called file_name and is on sdb3 (=(hd1,3)), start a Live CD Kubuntu session, openKonsole:

sudo fdisk -lu # to see/check your partitions, if necessary

Make a directory called /media/sdb3:

sudo mkdir /media/sdb3

Mount device sdb3 on directory /media/sdb3:

sudo mount /dev/sdb3 /media/sdb3

Change to that directory:

cd /media/sdb3

Then you may proceed in various ways:

Open Konqueror/Dolphin as root, then open the file_name:

in 8.10 or later: kdesudo konqueror (or dolphin)

in 8.04: kdesu konqueror (dolphin)Make your edits, then File > Save, File > Quit.

Or, open file_name as root using Kate, then do the edits:

in 8.10 or later: kdesudo kate /path_to file_name

in 8.04: kdesu kate /path_to file_name

Make your edits, then File > Save, File > Quit

Unmount the directory; note the spelling of umount:

sudo umount /media/sdb3

= = = = = = = = = = = = = = = = = = = =

= = = = = = = = = = = = = = = = = = = =

SECTION 4Special Topics

Installing GRUB 2 to your PC

grub-install The most useful command

The various types of command modes.

"c," grub>, Konsole BASH, edit "e", emu

TAB Completion

How to get information about your drives and devices

At Konsole : sudo fdisk -lu

At the GRUB 2 prompt: grub> ls

Boot menu: Adding or removing an OS entry

Boot menu: Create a custom boot entry

Boot menu: Making your own custom grub.cfgBoot menu: Changing resolution, text colors, setting background image

4 ways to boot an OS: configfile, symlinks, direct booting, chainloader

Dedicated GRUB 2 partition: How to build it

GRUB 2 Flashdrive: How to build it

Use of the term "root"

GRUB's Root Device, the Linux statement: root=UUID=,

--root-directory=DIR INSTALL_DEVICE

Dual booting: How to set it up

Booting XP on a non-first hard drive: The drivemap command in GRUB 2

Cheat sheet: GRUB 2 Practical Reminders


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- - - - -

Installing GRUB 2 To Your PC

To install GRUB 2 to your PC so it boots your PC into your OSs, two steps are required.

1 You need to get the GRUB 2 files installed to your PC, somewhere in the Kubuntu filesystem.

2 Then use those GRUB 2 files to install GRUB 2 to your PC's drives or devices so it can serve as a bootloader to boot

your PC into your Kubuntu and your other OSs.

Step 1: Get the GRUB 2 files

Install the GRUB 2 package in your Kubuntu OS using your package manager. Or, at Konsole, issue the following

command:

sudo apt-get install grub-pc

Check it: Open your file manager (Konqueror or Dolphin or other), and see the GRUB 2 files under

/usr/lib/grub/i386-pc (called the GRUB 2 image directory, and contains a set of "master" GRUB files).

Step 2: Install the GRUB 2 files so they serve as a bootloader

Suppose your first BIOS boot drive is sda (as seen in Kubuntu using at Konsole the command sudo fdisk -lu). Then,

install GRUB 2 to the Master Boot Record of sda:


This also copies the GRUB 2 files into /boot/grub.

Then to generate a fresh boot menu configuration file (/boot/grub/grub.cfg), run

sudo grub-mkconfig -o /boot/grub/grub.cfg.

More Details About This

CAUTION, fair warning:

Have a bootable Super Grub Disk CD handy in case this messes up booting your PC.

To install GRUB 2 files to your PC, open Konsole and run the commands

sudo apt-get updatesudo apt-cache search grub-pc

(returns: grub-pc - GRand Unified Bootloader, version 2 (PC/BIOS version))

sudo apt-get install grub-pc

Then, install GRUB 2 to the Master Boot Record of your first BIOS boot drive. For example, if that MBR is sda, the

command would be


And then update grub.cfg:


Reboot to see what happens.

The old GRUB may also still be there (in which case you saw an entry on the boot menu to chainload into GRUB 2), in

which case you may run

sudo update-from-grub-legacyto replace GRUB Legacy with GRUB 2 IF YOU WISH TO DO SO.

Troubleshooting

Installing GRUB 2 to the MBR: using --recheck

Example


grub-probe: error: cannot find a GRUB drive for /dev/sda.

Auto-detection of a filesystem module failed.

Please specify the module with the option `--modules' explicitly.

So, try this:

sudo grub-install --recheck /dev/sda


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-- Konsole (BASH), in Kubuntu, at your regular prompt (as root), ~#:

-- GRUB 2 emu (from Konsole, issue sudo grub-emu [OPTION]; this gives you a grub> prompt)

=>TODO: More on this later.

-- GRUB 2 command line interface (CLI), grub>.

When you re-boot your PC, get the boot menu, and press the "c" key, you get a GRUB 2 prompt, grub>. That is the

GRUB 2 CLI. You will also get "grub>" upon re-booting if you don't have a boot menu, grub.cfg, or if your boot menu

is broken. (See SECTION 3, the subsection titled "The GRUB prompt grub> -- What to do with it")

-- Edit mode. Editing on the fly: when you re-boot and see your GRUB 2 boot menu, you can use the "e" key to edit

your boot menu on a temporary basis (the edits are not permanent unless you later make them so). (See SECTION 3

-- Editing the boot menu during booting: "e" key.)

=> In all cases, help is nearby, and the commands are generally the same (or nearly so) in all modes, with a few

differences.

Help

Konsole BASH CLI:

Appending --help to a command in CLI; for example: grub-mkconfig --help.

GRUB CLI (grub>):

At the GRUB 2 prompt simply type help and press Enter.

To get help with a command, type help .

Example: grub>help ls tells you about the command ls.

Edit mode:The key tips are at the bottom of the screen after your press "e"

to enter the edit mode from your on-screen boot menu.

Also, at that point, you can press Control+c to get a grub>,

then type help and/or use TAB completion.

TAB completion (grub>)

While typing after the grub>, try pressing the TAB key and see what happens: in many cases, GRUB will try to help

you complete the line with something meaningful or with choices. So type as much as you can recall or type a guess,

then press TAB, then you may have to type another guess and press TAB again, and so on until you complete the line

the way you want it.

GRUB 2 device numbering is different(hdx,y): hard drive x, partition y

Hard drives start at zero (x=0), same as for GRUB Legacy.

Partitions start at 1 (y=1); in GRUB Legacy, partitions start at zero.

- - - - -

How to get information about your drives, devices, and files

Key: at Konsole sudo fdisk -lu; and grub> ls

We'll look at two cases: At the command line in Kubuntu (Konsole); and at the grub> prompt.

Konsole (BASH) command line

Exploring your hard drive(s): sudo fdisk -lu

=> sudo fdisk -lu is very useful, very important.

GRUB version number: grub-install -v

Drive space: df -h -T

UUIDs (see NOTE below):

blkid (or try sudo blkid); also:

ls /dev/disk/by-uuid/ -alh

grub.cfg, to see it: cat /boot/grub/grub.cfg

fstab (filesystem table), to see it: cat /etc/fstab

Mounting, how filesystems are mounted: cat /etc/mtab or: mount

Boot directory /boot, to find it: df /boot


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Kernel version and gcc version (gcc=the GNU compiler used to build the kernel):

cat /proc/version

Kernel version: uname -r

Linux version/name: lsb_release -a

(hold the Shift key and the minus sign key to get _ . LSB = Linux Standard Base)

KDE version (KDE=K Desktop Environment)

for KDE 3.5: kde-config version and for KDE 4: kde4-config --version

NOTE: UUID = Universally Unique Identifier

Starting with Kubuntu version 8.10, UUIDs are used to identify partitions. A UUID is a 16-byte number (= 128 bits).In canonical form, a UUID consists of 32 hexidecimal digits, displayed in 5 groups separated by hyphens.

At a GRUB prompt, grub>

Exploring your hard drive(s): grub> ls

=> Very useful, very important.

(in GRUB Legacy, the geometry command is used instead of ls)

The ls command is very useful

grub>ls

gives you a list of your hard drives and partitions as GRUB sees them, in (hdx,y) GRUB 2 device notation.

grub>ls /shows you the files under the current GRUB 2 root device. You can set that device using set root=. For example:

grub>set root=(hd0,8)

grub>ls /

shows you all files under root. Or: grub>ls (hd0,8)/ .

grub>ls /boot

shows you all files--including kernels--under /boot.

UUIDs and filesystem type

grub>ls (hd0,8)

shows you information about the partition (hd0,8) including its filesystem type and its UUID.

The contents of a directory: grub>ls -l /directoryExample

grub>ls -l /boot

shows you the kernel and initrd files.

(The option -l indicates "long form" and gives more information. To see all files, including hidden files, use the

option -a: grub>ls -a -l /boot; or grub>ls -al /boot)

GRUB 2 emulation sudo grub-emu

At Konsole, to get a grub> prompt, type sudo grub-emu.

To exit emu and return to Konsole, type exit.

>>> IMPORTANT sudo grub-emu and then grub>ls

While you are working at Konsole in Kubuntu, you may need to know how GRUB sees your drives and partitions, the

(hdx,y)'s. You can switch into emulation made (sudo grub-emu)) and issue the list (ls) command at the GRUB prompt(grub>ls) to see your drives and GRUB devices. Type exit to return to BASH mode in Konsole.

Using search and cat

GRUB files, what partitions they are in: grub>search /boot/grub/boot.img

Boot menu, what partition(s) it is in: grub>search /boot/grub/grub.cfg

Kernel, where it is: grub>search /vmlinuz

Boot menu, to see it: grub>cat (hdx,y)/boot/grub/grub.cfg

fstab, to see it: grub>cat (hdx,y)/etc/fstab

Device.map, to see it: grub>cat (hdx,y)/boot/grub/device.map

(NOTE: In GRUB Legacy, the find command is used instead of search.)


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Restart (reboot), or shutdown (halt) your PC at a command line

At Konsole:

sudo shutdown -r now (re-boots the PC)

sudo shutdown -h now (shuts down the PC)

In GRUB:

grub>reboot (re-boots the PC)

grub>halt (shuts down the PC)

- - - - -

Boot menu: Adding or removing an OS entry to grub.cfg

Rule: You do NOT edit grub.cfg directly. Instead, you work with script files in the folder /etc/grub.d or with settings

in /etc/default/grub.

-- Linux operating systems, added automatically

Look at your grub.cfg. The section

### BEGIN /etc/grub.d/10_linux ###

### END /etc/grub.d/10_linux ###

contains Linux operating systems that were automatically detected by GRUB 2 using the script file

/etc/grub.d/10_linux. Most of your Linux OSs should be detected this way and included in the boot menu grub.cfg.

If not, you can create a custom boot entry (see below, "Boot menu: Create a custom boot entry").

-- Windows and other OSs added automatically

This is done by the script /etc/grub.d/30_os-prober.

-- Adding or removing OSs from your PC. After doing so,

generate a new grub.cfg: sudo grub-mkconfig -o /boot/grub/grub.cfg.

-- Add a boot menu entry by making your own custom boot entry, then run:


to generate a new grub.cfg.

(See subsection below: "Boot menu: Create a custom boot entry")

-- Removing a boot entry from grub.cfg:

Two choices.

(1) Simply remove the execute bit from the script file in /etc/grub.d that corresponds to (i.e., generates) the boot

entry.

Example: If that file is named 43_MyOS-1, then run the Konsole commands

sudo chmod -x /etc/grub.d/43_MyOS-1


(2) Or, remove the script file (for the boot entry) from the folder /etc/grub.d. Then run

sudo grub-mkconfig -o /boot/grub/grub.cfg to generate the new grub.cfg file.

NOTE: If a custom file contains more than one boot entry, you may remove any number of them, leaving the rest.

Then use grub-mkconfig to generate your new boot menu, grub.cfg.

Boot menu: Custom boot entry

This is easy, usually.

-- There are 4 ways to make a boot entry (see "4 Ways To Boot an OS").

-- There is a custom template at /etc/grub.d/40_custom.

-- After you write the script file for your custom boot entry, make it executable.

-- Then generate a new grub.cfg by running sudo grub-mkconfig -o /boot/grub/grub.cfg.

Troubleshooting: Sometimes when you run grub-install or grub-mkconfig, it will fail to detect one of your OSs and

excludes it from the boot menu grub.cfg. In that case, you could make a custom entry for it (as a script file in

/etc/grub.d).


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Direct booting To get a model for some of the entries, you have two choices: (1) Get it from your old boot menu

(/boot/grub/menu.lst) from GRUB Legacy (if that is available on your PC). Or, it may also be here, made by GRUB 2:

menu.lst_backup_by_grub2_postinst. (2) Go into the operating system itself (the one you wish to include), or

perhaps access its filesystem using a live CD, and get the information from its own boot menu.

Example

Making a custom entry for sidux. Method: Direct booting.

It helps if you have a model for some of the entries. In the old boot menu (/boot/grub/menu.lst) from my GRUB

Legacy, I had this boot entry for sidux:

title Debian GNU/Linux, sidux kernel 2.6.28-5.slh.3-sidux-686

root (hd0,2)

kernel /boot/vmlinuz-2.6.28-5.slh.3-sidux-686 root=UUID=306d94a5-107b-4c9e-ae03-a159e18dc1c7 ro quiet

vga=791

initrd /boot/initrd.img-2.6.28-5.slh.3-sidux-686

Using a template (e.g., /etc/grub.d/40_custom), create an executable file for the sidux boot entry:

Open an empty text document (as root)

kdesudo kate

Save the new file as, say, /etc/grub.d/41_sidux_sda3

Copy the kernel & initrd lines from menu.lst, change kernel to linux, adjust the sidux partition number toconform to GRUB 2 convention:

Legacy GRUB: (hd0,2)

GRUB 2: (hd0,3)

Also, double check the UUID for sda3 by running sudo blkid.

Result:

The file /etc/grub.d/41_sidux_sda3 looks like this:

#!/bin/sh

echo "Adding sidux" >&2

cat


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set root=(hd1,2)

configfile /boot/grub/grub.cfg

An equivalent way of doing it is this:

configfile (hd1,2)/boot/grub/grub.cfg

That tells your GRUB 2 to access partition (hd1,2), find the file /boot/grub/grub.cfg, show you that file so you can

make a choice of which OS to boot, then boot the OS you choose. The GRUB doing the work is your native GRUB,

the one you are using, not the GRUB in (hd1,2). Your native GRUB must be able to interpret the commands it finds in

the grub.cfg of the OS you wish to boot.

When to avoid configfile

When there is a mixture of GRUB versions on your PC, it is best to avoid using configfile.

Instead, use chainloader or symlinks.

Example (Taken from a grub.cfg. The # sign indicates a comment.)

# Kubuntu 8.04.3 on sdb2, by configfile

menuentry Kubuntu 8.04.3 on sdb2, by configfile {

set root=(hd1,2)

configfile /boot/grub/grub.cfg

}

>>> Symlinks used in a boot entry

Symlinks are like shortcuts, and they direct control from the link to the file they point at. Symlinks for the kernel and

initrd files are already set up for you. Look for yourself. List all files (-a) in long or detailed form (-l) under your root

partition (/) by issuing the following command at Konsole:

ls -a -l /

lrwxrwxrwx 1 root root 33 2009-08-02 11:01 initrd.img -> boot/initrd.img-2.6.24-24-generic

lrwxrwxrwx 1 root root 33 2009-04-19 17:14 initrd.img.old -> boot/initrd.img-2.6.24-23-generic

lrwxrwxrwx 1 root root 30 2009-08-02 11:01 vmlinuz -> boot/vmlinuz-2.6.24-2 4-generic

lrwxrwxrwx 1 root root 30 2009-04-19 17:14 vmlinuz.old -> boot/vmlinuz-2.6.24-23-generic

The symlink for the kernel is vmlinuz, and vmlinuz points at the NEWEST kernel.

The symlink for the initrd is initrd.img, and initrd.img points at the NEWEST initrd.

NOTE: The "l" at the left indicates "link." Note how the links point at their target files following the symbol ->. Note

that the symlinks are stored in your OS at the root level.

NOTE: If you wish to make a boot entry for the older kernel and initrd, you must use the symlinks for them,

vmlinuz.old and initrd.img.old.

If you use direct booting, you have to write out the exact kernel and initrd names:

linux /boot/vmlinuz-2.6.24-24-generic root=UUID= vb687f89-ggjd-6ach-7755-77241i4b4fk3 ro quiet splashinitrd /boot/initrd.img-2.6.24-24-generic

With symlinks, vmlinuz starts at root and points at vmlinuz-2.6.24-24-generic and initrd.img starts at root and

points at initrd.img-2.6.24-24-generic, so you can write more simply,

linux /vmlinuz root=UUID= vb687f89-ggjd-6ach-7755-77241i4b4fk3 ro quiet splash

initrd /initrd.img

However, to simplify this when you are in an emergency trying to boot at the GRUB prompt (grub>), do it this way:

Suppose this OS is Kubuntu 9.10 in (hd0,8) = sda8. Then you'd have

menuentry Kubuntu 9.10 on sda8, by symlinks {


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set root=(hd0,8)

linux /vmlinuz root=/dev/sda8 ro quiet splash

initrd /initrd.img

}

or even simpler, when you can't remember the kernel options "ro quiet splash":

menuentry Kubuntu 9.10 on sda8, by symlinks {

set root=(hd0,8)

linux /vmlinuz root=/dev/sda8initrd /initrd.img

}

(ro = Read-Only and is the default. Thanks to dibl for this information.)

NOTE about the paths

Notice the paths to the symlinks start at root / (since the symlinks are stored under root /); whereas the paths to the

actual kernel & initrd files start at /boot (since the kernel and initrd are stored under /boot)

Another Example

# Kubuntu 9.10 on sdb7 symlinks, normal modemenuentry Kubuntu 9.10 on sdb7, by symlinks {

set root=(hd1,7)

linux /vmlinuz root=/dev/sdb7 ro quiet splash

initrd /initrd.img

}

This is normal mode. If you want recovery mode (single user),

replace the kernel options ro quiet splash with ro single (without quotes)

>>> Direct booting

In direct booting, you use the actual kernel and initrd file names in the boot menuentry.NOTE

If you use direct booting at the GRUB CLI, ie., at grub> prompt, you may use TAB completion to make your job easier.

For example,

grub>linux /boot/

and you will get some choices, such as vmlinuz-2.6.24-24-generic

Example

# Kubuntu 8.04 on sdb3, direct booting

menuentry "Kubuntu 8.04 on sdb3, direct booting" {

set root=(hd1,3)

linux /boot/vmlinuz-2.6.24-24-generic root=UUID=db287e84-cbdd-4ca1-8745-85241a3b3fe2 ro quiet splashinitrd /boot/initrd.img-2.6.24-24-generic

}

>>> Chainloader booting

When you boot an OS by chainloading, you use the chainloader command to pass control of the booting from your

native GRUB to some other bootloader located in the MBR of a disk somewhere or in the

boot sector of a partition.

NOTE: For this to work, a bootloader must first be installed to the target MBR or a partition boot sector.


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A Linux example

menuentry Kubuntu 9.10 on sdb7, by chainloader {

set root=(hd1,7)

chainloader +1

}

"chainloader +1" says to go to sector 1 (of (hd1,7)) and turn control over to the bootloader found there.

For this example to work, a bootloader (e.g., GRUB 2) must be installed to the partition (hd1,7).To install GRUB 2 to the boot sector of partition sdb7 (=(hd1,7)):

sudo grub-install /dev/sdb7

This is another way to write the same boot entry:

menuentry Kubuntu 9.10 on sdb7, by chainloader {

chainloader (hd1,7)+1

}

Another Linux example

menuentry Drive sdc = hd2 by chainloader {

chainloader (hd2)+1}

If a bootloader (e.g., GRUB 2) has been installed to the Master Boot Record of drive sdc (= hd2), the menuentry will

boot that hard drive by turning control over to the bootloader in its MBR.

For this example to work, a bootloader (e.g., GRUB 2) must be installed to the Master Boot Record of drive sdc (=

hd2). To install GRUB 2 to the Master Boot Record of drive sdc:

sudo grub-install /dev/sdc

Example

Windows XP on sda1menuentry Windows XP on sda1, by chainloader {

set root=(hd0,1)

chainloader +1

}

Dedicated GRUB 2 Partition: How To Build It

Again, this is straightforward, much easier than in GRUB Legacy.

1 Create the GRUB 2 partition.

Create a partition to be used as your dedicated GRUB 2 partition and format it. I use GParted Live CD to do this. Atthat time, you may if you wish, again using GParted, set a Label on your partition; e.g., GRUB2 (without the

quotation marks) (in GParted, use Partition > Labels).

(Check the size of the /boot/grub folder to determine how big to make the partition. GRUB 2 files use just 572 KB

(96 files, including 12 old ones) on my installation.)

2 Create grub.cfg.

In your home directory, create a text file called grub.cfg and build your custom boot menu for the dedicated GRUB 2

partition. (For a sample, see below.)

(To create the text file, two ways: (1) Right-click on your Desktop, Create New > Text File; or (2) open text editor

Kate to an empty document by typing at Konsole kate and save it under the name grub.cfg in your home directory

only! To do this as root, use kdesudo kate, but that is not necessary at this point.)


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Caution: You may want to completely build your boot menu now and have it ready to go. To make your boot entries

in your grub.cfg, see the subsection above "4 Ways To Boot an OS."

3 Install GRUB 2 to the MBR.

From your Kubuntu OS, install GRUB 2 to the Master Boot Record (of your first BIOS boot drive) using GRUB 2 files

set up in your dedicated GRUB 2 partition.

Example

Suppose sdb1 is your dedicated GRUB 2 partition, and assume it is mounted as /media/sdb1 (or, if you set the label

GRUB2 on sdb1, this might be /media/GRUB2). And suppose you wish to install GRUB 2 to the MBR of sda which is

set in BIOS to be your first boot drive.Do it this way:

sudo grub-install root-directory=/media/sdb1 /dev/sda

See: http://grub.enbug.org/FranklinPiat/grub-install.manpage

(That will also build the directory /boot/grub for you in your GRUB 2 partition.)

4 As root, copy your grub.cfg from your home directory to the GRUB 2 partition under the folder /boot/grub. (To

do this in GUI, open your file manager as root and work from there; e.g., kdesudo konqueror or kdesudo dolphin.)

5 Set the boot flag on your dedicated GRUB 2 partition and re-boot to test it.

Set the boot flag on the dedicated GRUB 2 partition:

Do that using GParted either from your OS (K > System > Partition editor) or from the GParted Live CD. If you do itusing the GParted Live CD, you might go this way now:

After completing Step 4 (copying the grub.cfg file into the partition), put the GParted Live CD in the CD tray, let it be

recognized, re-boot into GParted Live, set the boot flag on your dedicated GRUB 2 partition (Partition > Manage

Flags), GParted > Quit, then double click GParted (large menu at top) to quit and re-boot, when prompted remove

the GParted Live CD, and let the PC re-boot (and it will now be using your dedicated GRUB 2 partition), and see if it

works.

CAUTION: Remember to keep Super Grub Disk live CD handy.

IMPORTANT NOTE ABOUT KERNEL UPDATES:

Using this method of building a dedicated GRUB 2 partition, YOU are in charge of the boot configuration file

/boot/grub/grub.cfg that is located in the GRUB 2 partition. The stuff we talked about above--/etc/default/grub andthe scripts /etc/grub.d and grub-mkconfig--does not apply. You must keep these two "shows" separate. Edit the

dedicated GRUB 2 file grub.cfg manually. If there ever is a problem, you may have to manually re-install GRUB 2 to

the MBR (of the first BIOS boot drive) from the dedicated GRUB 2 partition.

Example Here's my dedicated GRUB 2 /boot/grub/grub.cfg:

# grub.cfg

# This is my custom boot menu, called /boot/grub/grub.cfg, located in my dedicated Grub 2 partition sda1.

# Set the timeout

set timeout=10

# Set the default boot entry.

set default=0

# Kubuntu 9.10 on sda8 by chainload

menuentry "Kubuntu 9.10 on sda8, by chainload" {

chainloader (hd0,8)+1

}

# Kubuntu 9.10 on sda8 by configfile

menuentry "Kubuntu 9.10 on sda8, by configfile" {

configfile (hd0,8)/boot/grub/cfg


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}

# Kubuntu 9.10 on sda8 by symlink

menuentry "Kubuntu 9.10 on sda8, by symlink" {

set root=(hd0,8)

linux /vmlinuz root=/dev/sda8 ro quiet splash

initrd /initrd.img

}

# Kubuntu 8.04.3 on sda2, by configfilemenuentry "Kubuntu 8.04.3 on sda2, by configfile" {

configfile (hd0,2)/boot/grub.cfg

}

# sidux on sda3, by direct booting

menuentry "sidux on sda3" {

set root=(hd0,3)

linux /boot/vmlinuz-2.6.28-5.slh.3-sidux-686 root=UUID=306d94a5-107b-4c9e-ae03-a159e18dc1c7 ro quiet

vga=791

initrd /boot/initrd.img-2.6.28-5.slh.3-sidux-686

}

GRUB 2 Flashdrive (USB flash drive)

For the principles of installing GRUB 2, see the discussion under "Installing GRUB 2" and "The grub-install

Command."

Example

I used a 1 GB Kingston; the GRUB 2 files used just 51 MB.

Partition and format the flash drive as ext2 (using GParted Partition Editor). (You could also use FAT32 or ext3 or

some other filesystem.)Set the boot flag on the newly created partition (use GParted to do that: Partition > Manage Flags).

Exit GParted. Unplug the flashdrive, then plug it in.

In Kubuntu, to see how it is named, at Konsole run

sudo fdisk -lu

Output:

Disk /dev/sdb: 1031 MB, 1031798784 bytes

255 heads, 63 sectors/track, 125 cylinders, total 2015232 sectors

Units = sectors of 1 * 512 = 512 bytes

Disk identifier: 0x000f0fe1

Device Boot Start End Blocks Id System

/dev/sdb1 63 2008124 1004031 83 Linux

Konqueror (or Dolphin) indicated it is mounted as /media/disk.

=> So it is seen as sdb with the partition sdb1 mounted as /media/disk.

Install GRUB 2 to the flash drive. At Konsole:

sudo grub-install --root-directory=/media/disk /dev/sdb

Output:

Installation finished. No error reported.

This is the contents of the device map /media/disk/boot/grub/device.map.

Check if this is correct or not. If any of the lines is incorrect,


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fix it and re-run the script `grub-install'.

(hd0) /dev/sda

(hd1) /dev/sdb

(This is the device.map on the flash drive, /boot/grub/device.map. I will ignore this! Doesn't matter too much. You

could edit it as root to read

(hd0) /dev/sda

as seen from the point of view of the flash drive when it is used as a boot drive.)

Let's move on, now ...

Check to see that /boot/grub is created and filled with GRUB 2 files.

Reboot, setting BIOS to boot from the flash drive (USB booting).

The next thing I saw on the screen was:

grub>

I used the GRUB 2 command ls to see my drives and partitions (on the PC):

grub>ls

Since the PC booted from the flash drive, it was seen as hd0 with partition (hd0,1). (The drive that the PC actually

boots from is always seen during its booting session as hd0--this is a general fact.)

My regular HDD, normally seen as hd0 was now seen as hd1 and my Kubuntu 9.10 was in (hd1,8).So, to boot into Kubuntu, I did

grub>chainloader (hd1,8)+1

grub>boot

NOTE:

Previously I had already installed GRUB 2 to the partition boot sector of Kubuntu in case I ever needed to chainload

into it. (I used at Konsole in Kubuntu, sudo grub-install /dev/sda8, where sda8 is my Kubuntu partition when there is

no other drive attached to the PC.) Had I not already done this, I could could NOT chainload into Kubuntu and would

have to boot into Kubuntu in some other way, for example using symlinks:

grub>ls

would show me that Kubuntu is on (hd1,8) when booting from my GRUB 2 flash drive, and so to boot it, I'd do:


grub>linux /vmlinuz root=/dev/sda8grub>initrd /initrd.img

grub>boot

Or, you could do this (if you remembered how!):


grub>linux /vmlinuz root=/dev/sda8 ro quite splash

grub>initrd /initrd.img

grub>boot

Thus, I booted into Kubuntu using the GRUB 2 flash drive.

Building a boot menu for the flash drive:

You can create a text file /boot/grub/grub.cfg for the flash drive exactly as demonstrated under building a DedicatedGRUB 2 Partition.

Technical Note: To do so, you will probably have to work as root, say by opening Konqueror or Dolphin as root

(kdesudo konqueror), or by opening Kate as root (kdesudo kate). However, you do not necessarily need a grub.cfg

on the flash drive. You can simply use it as I did to explore your drives and then boot into an OS. If you do build a

grub.cfg for it, you might include the OS(s) on your hard drive(s), and use the GRUB 2 flash drive to boot in

emergencies, as you would use Super Grub Disk. Just remember that from the point of view of the grub.cfg on your

flash drive, the other drives in your PC are shifted by 1 since upon booting the flash drive, it will be seen as hd0. If

adrian15 builds Super Grub Disk for GRUB 2 and includes his usbshift function, then the story changes--for the

principle of "USB drive shifting," see my how on building a GRUB flash drive:

-- How To Make GRUB Thumb Drive


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/etc/grub.d Folder of boot menu scripts:

00_header; 05_debian_theme: Background, text colors, themes

10_hurd Locates Hurd kernels; 10_linux Locates Linux kernels; 20_memtest86+

30_os-prober: Searches for Linux and other OS's on all partitions

40_custom: Template for custom boot menu entries

More: /boot/grub/device.map, boot.img (MBR), core.img

Fixing Things, Rescue

Ctrl+Alt+Del reboot PC; Super Grub Disk

New grub.cfg: sudo grub-mkconfig -o /boot/grub/grub.cfgInstall, re-install GRUB 2: sudo grub-install [INSTALL_DEVICE]

to MBR: sudo grub-install /dev/sdx; partition: sudo grub-install /dev/sdxn

If error: grub-install --recheck /dev/sdx; sudo grub-install --recheck /dev/sdxn

Install GRUB 2 to MBR of sda using GRUB 2 in /dev/sdb1/boot/grub:


Install GRUB 2 to PC (/usr/lib/grub/i386-pc/): sudo apt-get install grub-pc

Live CD rescue: Re-install GRUB 2

sudo mkdir /media/sda2 /media/dev

sudo mount /dev/sda2 /media/sda2

sudo mount --bind /dev /media/dev

Install GRUB 2 to MBR of sdb [or to partition sda2] using GRUB 2 files in sda2:sudo grub-install --root-directory=/media/sda2 /dev/sdb [or /dev/sda2]

umount /media/sda2 /media/dev

Drives, partitions, information sudo fdisk -lu & grub>ls

Naming: (hdx,y) or sdzy: drive x starts at 0; partitions y start at 1

Konsole: sudo fdisk -lu; df -hT; mounting: cat /etc/mtab; or: mount

UUIDs: sudo blkid; ls /dev/disk/by-uuid/ -alh

Kernel ver: uname -r; cat /proc/version; Linux ver: lsb_release -a

sudo grub-emu and then grub>ls

GRUB devices/drives: grub>ls; grub>ls -al directory

UUID of (hdx,y): grub>ls (hdx,y)

Finding: grub>search /boot/grub/grub.cfg; grub>search /boot/grub/boot.img

Syntax, booting choices

configfile: set root=(hdx,y) and configfile /boot/grub/grub.cfg; or:

configfile (hdx,y)/boot/grub/grub.cfg

symlinks: linux /vmlinuz root=UUID= xxx ro quiet splash; initrd /initrd.img

symlinks: linux /vmlinuz root=/dev/sdxn ro quiet splash

chainload: set root=(hdx,y) and chainloader +1; chainloader (hdx,y)+1

chainload a MBR: chainloader (hdx)+1

Permissions

Executable: sudo chmod 744 /etc/grub.d/file; Remove: sudo chmod -x /etc/grub.d/file

Read only, everyone: sudo chmod 444 /etc/grub.d/fileGUI: kdesudo konqueror (dolphin), rt-click onfile, Properties, Permissions

grub.cfg: sudo chmod +w /boot/grub/grub.cfg; sudo chmod -w /boot/grub/grub.cfg

Create a script called /etc/grub.d/NN_myscript

Empty text doc: kdesudo kate; File > Save As /etc/grub.d/NN_myscript

Type it (see template below).

Make executable: sudo chmod 744 /etc/grub.d/NN_myscript

or, sudo chmod +x /etc/grub.d/NN_myscript

GUI: kdesudo konqueror (dolphin), rt-click, Properties, Permissions

Make new grub.cfg: sudo grub-mkconfig -o /boot/grub/grub.cfg


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> Template, custom boot entry for file /etc/grub.d/NN_name

#!/bin/sh

echo "Adding name" >&2

cat Save, Exit. New grub.cfg: sudo up-date grub; sudo grub-mkconfig

Flash drive /dev/sdc, sdc1 mounted at /media/disk; set boot flag; install GRUB 2:

sudo grub-install --root-directory=/media/disk /dev/sdc

Separate GRUB 2 partition: mounted at /media/sdb1; sda=MBR of 1st BIOS drive


Working as root (8.10+: kdesudo; 8.04: kdesu)

kdesudo kate /path-to-file; kdesudo konqueror (or dolphin)

Terminal as root: sudo i; sudo su

GUI file manager, navigate to file, right-click on file, Actions, Edit as Root.

sudo [COMMAND]; sudo grub-install [INSTALL_DEVICE];


[End of GRUB 2 Practical Reminders]

= = = = = = = = = = = = = = = = = = = =

= = = = = = = = = = = = = = = = = = = =

Appendix: Techniques

--- Installing Kubuntu--GRUB 2 placement

--- Working as root

--- Permissions: read, write, execute; change the execute bit

--- Chroot -- how to

See Part 3 of Commands at Konsole: Beginners: 3 parts

http://kubuntuforums.net/forums/index.php?topic=3091607.0

= = = = = = = = = = = = = = = = = = = =

Installing Kubuntu--GRUB 2 placement

Live CD method

The Live CD method of installing Kubuntu is easy, fast, and convenient because afterwards, you then have a Live CD

to use for rescue and repair of your system.

Installing GRUB 2 files

GRUB 2 is standard on Kubuntu starting with 9.10. During its installation from the Live CD, you can specify if you

want GRUB 2installed, and if so, where to put it. Here's how:

Start the Live CD installer.

Step: Disk Setup

"Specify Partitions Manually"


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Step: Summary

Advanced button at lower right

Check or un-check to install GRUB 2 bootloader

Choose from the drop-down list where to install GRUB 2

sda = the MBR of drive sda

sda1 = the first partition of drive sda

sdb = the MBR of drive sdb

etc.

Caution:

> If you install GRUB to a MBR (sda, sdb, sdc, etc.), it will overwrite any other bootloader already installed to that

MBR, and the GRUB 2 from the OS you are currently installing will then control the boot menu you see when you

boot up your PC. That is OK, just so you know.

> If you install GRUB 2 to the partition boot sector where you are currently installing the OS (e.g., sdan, for some

n=1,2,3,4...), when you re-boot your PC, you will have to manually boot into your new OS you just installed. Do so

using chainloader, as follows:

-- Re-boot

-- If you get some boot menu (from a prior Linux OS installation), press the "c" key to get a GRUB prompt, grub>. If

you don't get a boot menu but only the GRUB prompt grub>, then that's OK, too.

-- Let's say your new Kubuntu OS was installed to sda9. That is the same as (hd0,9). Thengrub>chainloader (hd0,9)+1

grub>boot

and you will boot into your new OS.

Building new boot menus

> In your new OS, you can build a full boot menu simply by doing sudo grub-mkconfig -o /boot/grub/grub.cfg.

> In your existing OSs, you can re-build boot menus to include the new OS the same way:

Konsole


> Worst case, if for some reason that doesn't work, you can make a custom boot entry to include your new OS. See

SECTION 4. To get the details of the menuentry for the new OS for the existing grub.cfg, you might have to boot

into the new OS and copy details from its grub.cfg. Or, simply boot your new OS using symlinks or chainloader (from

another OS's boot menu), for which you do not need any details specific to the new OS. See SECTION 4, "4 Ways to

boot an OS."

= = = = = = = = = = = = = = = = = = = =

Working as root

Opening a text editor (e.g., Kate, Kwrite, etc.) to see the file and/or to edit it:

kdesudo kate path-to-file

Example: kdesudo kate /etc/fstab

Opening an empty text document as root:

kdesudo kate

(then File > Save As)

Opening a file manager as root:

in 8.10 and after: kdesudo konqueror (or dolphin)

in 8.04: kdesu konqueror (dolphin)

Opening a terminal as root:

sudo i (to get a root terminal)


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http://www.gnu.org/software/grub/grub-2.en.html

GNU GRUB, main site, Legacy GRUB

http://www.gnu.org/software/grub/

GRUB Wiki: grub.cfg

http://grub.enbug.org/grub.cfg

GRUB 2 Commands, GRUB Wiki

http://grub.enbug.org/CommandListCompares GRUB Legacy to GRUB 2 commands.

GRUB 2: Live CD Install Guide

http://grub.enbug.org/Grub2LiveCdInstallGuide

StartUp-Manager

https://help.ubuntu.com/community/StartUpManager

GRUB & GRUB 2 Boot Process

http://www.pixelbeat.org/docs/disk/

Bootloaderhttp://en.wikipedia.org/wiki/Boot_loader

GNU GRUB

http://en.wikipedia.org/wiki/GRUB

Boot Options

https://help.ubuntu.com/community/BootOptions

Kernel Parameters

http://www.kernel.org/doc/Documentation/kernel-parameters.txt

Grub Legacy-- How To GRUB Methods - Toolkit

http://kubuntuforums.net/forums/index.php?topic=3081671.0

GParted Live CD

http://gparted.sourceforge.net/livecd.php

For partitioning, formatting your hard drive.

Super Grub Disk

http://www.supergrubdisk.org/

Will boot you into your OS when you can't do it alone.

Arch Linux, ArchWiki GRUB 2http://wiki.archlinux.org/index.php/GRUB2

Experiences in the Community, Jaunty and GRUB2

http://flossexperiences.wordpress.com/2008/11/19/jaunty-and-grub2/

GRUB 2 installation

http://www.techenclave.com/guides-and-tutorials/grub-2-installation-92883.html

GRUB2 Theming



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KernelTeam/Grub2Testing

https://wiki.ubuntu.com/KernelTeam/Grub2Testing

Using UUID

https://help.ubuntu.com/community/UsingUUID

BIOS Boot Partition, and what does GRUB use it for?

http://grub.enbug.org/BIOS_Boot_Partition

GUID Partition Tablehttp://en.wikipedia.org/wiki/GUID_Partition_Table

Technical Note TN2166, Secrets of the GPT

http://developer.apple.com/mac/library/technotes/tn2006/tn2166.html

HOWTO: Booting LiveCD ISOs from USB flash drive with Grub2, by JustRon.


Booting LiveCD from HD ISO


Boot an iso via Grub 2http://michael-prokop.at/blog/2009/05/25/boot-an-iso-via-grub2/

MultiBoot USB with Grub2 (boot directly from iso files)

http://www.panticz.de/MultiBootUSB

GRUB Graphical Menu Development Journal

http://grub.gibibit.com/Journal

Debian Wiki, GRUB, grub.cfg

http://wiki.debian.org/Grub/grub.cfg.manpage

As of 9-9-09, it doesn't exist.

Tweaking GRUB 2

http://www.drlock.com/blog/2008/07/11/tweaking-grub-2/

GRUB 2 configuration, shirish

http://www.techenclave.com/guides-and-tutorials/grub-2-configuration-93512.html

How To Install GRUB 2 On Ubuntu 9.04

http://www.linuxtoday.com/news_story.php3?ltsn=2009-09-02-005-35-OS-HL-SM

Documents

GRUB 2 - A Guide for Users