Explain my Menu.lst

Johnny Faster · 06-21-2006, 04:03 AM

I recently posted a thread asking how to edit the boot order in my menu.lst file and have just managed to do so. Haven't tried to re-boot yet, but it seemed fairly simple and so I am confident that all will work well.

However, while looking over the file I see a lot of entries, and as I am a new User, I think it would be good to understand this file, what it contains and what the entries mean and do.

So I am posting it here as a reference for future questions regarding the file that I may ask in this thread.

I don't know if there is any information in this file that should not be made public (nothing jumps out at me) but if there is please let me know.

Quote:

# menu.lst - See: grub(8), info grub, update-grub(8)
# grub-install(8), grub-floppy(8),
# grub-md5-crypt, /usr/share/doc/grub
# and /usr/share/doc/grub-doc/.

## default num
# Set the default entry to the entry number NUM. Numbering starts from 0, and
# the entry number 0 is the default if the command is not used.
#
# You can specify 'saved' instead of a number. In this case, the default entry
# is the entry saved with the command 'savedefault'.
# WARNING: If you are using dmraid do not change this entry to 'saved' or your
# array will desync and will not let you boot your system.
default 0

## timeout sec
# Set a timeout, in SEC seconds, before automatically booting the default entry
# (normally the first entry defined).
timeout 10

## hiddenmenu
# Hides the menu by default (press ESC to see the menu)
#hiddenmenu

# Pretty colours
#color cyan/blue white/blue

## password ['--md5'] passwd
# If used in the first section of a menu file, disable all interactive editing
# control (menu entry editor and command-line) and entries protected by the
# command 'lock'
# e.g. password topsecret
# password --md5 $1$gLhU0/$aW78kHK1QfV3P2b2znUoe/
# password topsecret

#
# examples
#
# title Windows 95/98/NT/2000
# root (hd0,0)
# makeactive
# chainloader +1
#
# title Linux
# root (hd0,1)
# kernel /vmlinuz root=/dev/hda2 ro
#

#
# Put static boot stanzas before and/or after AUTOMAGIC KERNEL LIST

### BEGIN AUTOMAGIC KERNELS LIST
## lines between the AUTOMAGIC KERNELS LIST markers will be modified
## by the debian update-grub script except for the default options below

## DO NOT UNCOMMENT THEM, Just edit them to your needs

## ## Start Default Options ##
## default kernel options
## default kernel options for automagic boot options
## If you want special options for specific kernels use kopt_x_y_z
## where x.y.z is kernel version. Minor versions can be omitted.
## e.g. kopt=root=/dev/hda1 ro
## kopt_2_6_8=root=/dev/hdc1 ro
## kopt_2_6_8_2_686=root=/dev/hdc2 ro
# kopt=root=/dev/sda2 ro

## default grub root device
## e.g. groot=(hd0,0)
# groot=(hd1,1)

## should update-grub create alternative automagic boot options
## e.g. alternative=true
## alternative=false
# alternative=true

## should update-grub lock alternative automagic boot options
## e.g. lockalternative=true
## lockalternative=false
# lockalternative=false

## additional options to use with the default boot option, but not with the
## alternatives
## e.g. defoptions=vga=791 resume=/dev/hda5
# defoptions=quiet splash

## altoption boot targets option
## multiple altoptions lines are allowed
## e.g. altoptions=(extra menu suffix) extra boot options
## altoptions=(recovery mode) single
# altoptions=(recovery mode) single

## controls how many kernels should be put into the menu.lst
## only counts the first occurence of a kernel, not the
## alternative kernel options
## e.g. howmany=all
## howmany=7
# howmany=all

## should update-grub create memtest86 boot option
## e.g. memtest86=true
## memtest86=false
# memtest86=true

## should update-grub adjust the value of the default booted system
## can be true or false
# updatedefaultentry=false

## ## End Default Options ##

title Ubuntu, kernel 2.6.15-25-386
root (hd1,1)
kernel /boot/vmlinuz-2.6.15-25-386 root=/dev/sda2 ro quiet splash
initrd /boot/initrd.img-2.6.15-25-386
savedefault
boot

title Ubuntu, kernel 2.6.15-25-386 (recovery mode)
root (hd1,1)
kernel /boot/vmlinuz-2.6.15-25-386 root=/dev/sda2 ro single
initrd /boot/initrd.img-2.6.15-25-386
boot

title Ubuntu, kernel 2.6.15-23-386
root (hd1,1)
kernel /boot/vmlinuz-2.6.15-23-386 root=/dev/sda2 ro quiet splash
initrd /boot/initrd.img-2.6.15-23-386
savedefault
boot

title Ubuntu, kernel 2.6.15-23-386 (recovery mode)
root (hd1,1)
kernel /boot/vmlinuz-2.6.15-23-386 root=/dev/sda2 ro single
initrd /boot/initrd.img-2.6.15-23-386
boot

title Ubuntu, memtest86+
root (hd1,1)
kernel /boot/memtest86+.bin
boot

### END DEBIAN AUTOMAGIC KERNELS LIST

# This is a divider, added to separate the menu items below from the Debian
# ones.
title Other operating systems:
root

# This entry automatically added by the Debian installer for a non-linux OS
# on /dev/hdc1
title Microsoft Windows XP Home Edition
root (hd0,0)
savedefault
makeactive
chainloader +1

# This entry automatically added by the Debian installer for a non-linux OS
# on /dev/sda1
title Windows NT/2000/XP (loader)
root (hd1,0)
savedefault
makeactive
map (hd0) (hd1)
map (hd1) (hd0)
chainloader +1

binary_y2k2 · 06-21-2006, 04:17 AM

There's a lot of items in the menu.lst, but it't well a comented file, you should also try

Code:

man grub

but there is more in /usr/share/doc/grub/ and if you install grub-doc then more docs in /usr/share/doc/grub-doc/.
The grub-doc files are in HTML and give lots of info on grub.

m_yates · 06-21-2006, 07:36 AM

Every line starting with "#" is a comment.

Every line starting with "title" is the start of an entry. In your case, you have 8 entries. They are numbered starting with 0.

The "Default" line states what entry you want be selected by default. In your case it is number 0, or the first entry (the latest Ubuntu kernel 2.6.15-25-386).

If you want to boot something else by default, you can either (1) Cut and past the entry you want to boot by default to move it first, so that it becomes number 0, or (2) Change the default number.

For example, in your case if you want Windows XP Home Edition to boot by default, you could change the default number to 6, OR you could cut the entire Windows XP Home entry and paste it above the first Ubuntu entry so that Windows XP Home Edition becomes number 0.

The "timeout" line sets how long you have before the default entry is booted. During that time, you can use up/down arrow keys and the enter key to select and alternate entry.

Another option useful to some is "hiddenmenu". If you add a line under timeout that has "hiddenmenu", you won't see the menu entries and the default one will just be booted. Hiddenmenu is really only useful if you are not dual booting with Windows.

Finally, there is usually no need to keep multiple kernels if the latest one is working properly. The extra kernels take up a lot of disk space. You can get rid of the old kernel with:

Code:

sudo dpkg -P linux-image-2.6.15-23-386

Any time you add or remove a kernel, the menu.lst file will be automatically edited to change the entries. You can go back and make manual changes later if you want.

Johnny Faster · 06-21-2006, 01:44 PM

Quote:

Finally, there is usually no need to keep multiple kernels if the latest one is working properly. The extra kernels take up a lot of disk space. You can get rid of the old kernel with:

I read the word "kernel" constantly but do not have a clear sense of exactly what a kernel is.

Excatly what is a kernel, and why is the word used so frequently?

Also, I have read several references to an (Ubuntu) "User Manual". Does one exist ? If so, how can I get one ?

Thanks in advance,

Johnny

m_yates · 06-21-2006, 03:12 PM

The kernel is really the linux operating system: http://en.wikipedia.org/wiki/Kernel_...ter_science%29 It is the communication layer between software and hardware.

The Ubuntu manual is here: http://ubuntuguide.org/

jstephens84 · 06-22-2006, 10:29 AM

Think of the kernel as the core of everything. Pretty much everything is built around it. Kde and gnome are the window managers or interfaces to the core. ( I hope I am saying this right. I know what I am thinking but it's hard to write down.) If you would like to learn more about the linux kernel I would suggest two really good books.

1)Linux kernel Development. http://www.amazon.com/gp/product/067...Fencoding=UTF8

2)Understanding the linux kernel
http://www.amazon.com/gp/product/059...Fencoding=UTF8