机器上装了双系统(Ubuntu 8.10+WinXP)，每次启动的时候如果不在Grub那里选择WinXP的话就会默认启动到Ubuntu。但是一般我都是用WinXP的，这样每次选择对我这种懒人来说太麻烦了，所以今天我就修改了Grub的配置，让它默认启动WinXP...

我们进入Ubuntu后，打开终端，先备份一下Grub的启动列表文件menu.lst：

这个0就代表了Grub默认启动项为Ubuntu，而我们要改成...这个因机而已了，我们往下看。
# 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 use 'savedefault' 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=UUID=898431cf-4249-4de1-a492-7e2f4afd49a9 ro locale=zh_CN

## default grub root device
## e.g. groot=(hd0,0)
# groot=3738b672-62f3-490d-916a-cad379fdb57b

## 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

## should update-grub lock old automagic boot options
## e.g. lockold=false
##      lockold=true
# lockold=false

## Xen hypervisor options to use with the default Xen boot option
# xenhopt=

## Xen Linux kernel options to use with the default Xen boot option
# xenkopt=console=tty0

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

## should update-grub add savedefault to the default options
## can be true or false
# savedefault=false

## ## End Default Options ##

title        Ubuntu 8.10, kernel 2.6.27-11-generic
uuid        3738b672-62f3-490d-916a-cad379fdb57b
kernel        /vmlinuz-2.6.27-11-generic root=UUID=898431cf-4249-4de1-a492-7e2f4afd49a9 ro locale=zh_CN quiet splash
initrd        /initrd.img-2.6.27-11-generic
quiet

title        Ubuntu 8.10, kernel 2.6.27-11-generic (recovery mode)
uuid        3738b672-62f3-490d-916a-cad379fdb57b
kernel        /vmlinuz-2.6.27-11-generic root=UUID=898431cf-4249-4de1-a492-7e2f4afd49a9 ro locale=zh_CN  single
initrd        /initrd.img-2.6.27-11-generic

title        Ubuntu 8.10, kernel 2.6.27-7-generic
uuid        3738b672-62f3-490d-916a-cad379fdb57b
kernel        /vmlinuz-2.6.27-7-generic root=UUID=898431cf-4249-4de1-a492-7e2f4afd49a9 ro locale=zh_CN quiet splash
initrd        /initrd.img-2.6.27-7-generic
quiet

title        Ubuntu 8.10, kernel 2.6.27-7-generic (recovery mode)
uuid        3738b672-62f3-490d-916a-cad379fdb57b
kernel        /vmlinuz-2.6.27-7-generic root=UUID=898431cf-4249-4de1-a492-7e2f4afd49a9 ro locale=zh_CN  single
initrd        /initrd.img-2.6.27-7-generic

title        Ubuntu 8.10, memtest86+
uuid        3738b672-62f3-490d-916a-cad379fdb57b
kernel        /memtest86+.bin
quiet

### 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/sda1

title        Microsoft Windows XP Professional
root        (hd0,0)
savedefault
makeactive
chainloader    +1
恩，我用了7种不同的颜色标记了下面的每一部分，依次编号为0、1、2、3、4、5、6。所以我们看到WinXP系统的编号是6，所以我们只要把 default        0 修改为 default        6 就可以了。

这个是我的电脑，XP的编号为6，你的电脑需要你自己去看是多少。

PS.这里有个技巧，你需要数有多少个title就可以啦，哈哈！

另外上面我不同颜色标记的东西是可以删除的，删除以后Grub启动列表里的对应项目就会消失，貌似可以美观一些，嘎嘎...