開啟終端，su命令切換到root許可權，使用vi開啟“grub.conf”檔案（vi /etc/grub.conf），內容如下：# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE: You have a /boot partition. This means that
# all kernel and initrd paths are relative to /boot/, eg.
# root (hd0,4)
# kernel /vmlinuz-version ro root=/dev/VolGroup00/LogVol00
# initrd /initrd-version.img
#boot=/dev/sda
default=2
timeout=5
splashimage=(hd0,4)/grub/splash.xpm.gz
hiddenmenu
title Fedora (2.6.23.15-80.fc7)
root (hd0,4)
kernel /vmlinuz-2.6.23.15-80.fc7 ro root=/dev/VolGroup00/LogVol00 rhgb quiet
initrd /initrd-2.6.23.15-80.fc7.img
title Fedora (2.6.21-1.3194.fc7)
root (hd0,4)
kernel /vmlinuz-2.6.21-1.3194.fc7 ro root=/dev/VolGroup00/LogVol00 rhgb quiet
initrd /initrd-2.6.21-1.3194.fc7.img
title Microsoft Windows Option System
rootnoverify (hd0,0)
chainloader +1
其中“default=2”便是預設啟動項，改變他即可。
vi編輯器的使用：http://www.cnblogs.com/EasyData/archive/2008/04/17/1157434.html
