在终端里输入：sudo gedit /boot/grub/grub.cfg
先装windows而后装linux系统，默认启动项会非常多，执行上面的命令后，会打开一个文档，里面代码如下：
---------------------------------------------------------------------------------------------------------------( 这些小横线是我自己加的)
## DO NOT EDIT THIS FILE## It is automatically generated by /usr/sbin/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 load_envfiset default="8"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=truefifunction 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 ${boot_once} ]; then save_env recordfail; fi; fi}insmod ext2set root='(hd0,9)'search --no-floppy --fs-uuid --set fd9c0f6c-5c20-4d95-b3f4-eebca82bea0fif loadfont /usr/share/grub/unicode.pf2 ; then set gfxmode=640x480 insmod gfxterm insmod vbe if terminal_output gfxterm ; then true ; else # For backward compatibility with versions of terminal.mod that don't # understand terminal_output terminal gfxterm fifiinsmod ext2set root='(hd0,9)'search --no-floppy --fs-uuid --set fd9c0f6c-5c20-4d95-b3f4-eebca82bea0fset locale_dir=($root)/boot/grub/localeset lang=zhinsmod gettextif [ ${recordfail} = 1 ]; then set timeout=-1else set timeout=10fi### END /etc/grub.d/00_header ###### BEGIN /etc/grub.d/05_debian_theme ###set menu_color_normal=white/blackset menu_color_highlight=black/light-gray### END /etc/grub.d/05_debian_theme ###### BEGIN /etc/grub.d/10_linux ###menuentry 'Ubuntu, with Linux 2.6.32-31-generic' --class ubuntu --class gnu-linux --class gnu --class os { recordfail insmod ext2 set root='(hd0,9)' search --no-floppy --fs-uuid --set fd9c0f6c-5c20-4d95-b3f4-eebca82bea0f linux /boot/vmlinuz-2.6.32-31-generic root=UUID=fd9c0f6c-5c20-4d95-b3f4-eebca82bea0f ro quiet splash initrd /boot/initrd.img-2.6.32-31-generic}menuentry 'Ubuntu, with Linux 2.6.32-31-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os { recordfail insmod ext2 set root='(hd0,9)' search --no-floppy --fs-uuid --set fd9c0f6c-5c20-4d95-b3f4-eebca82bea0f echo 'Loading Linux 2.6.32-31-generic ...' linux /boot/vmlinuz-2.6.32-31-generic root=UUID=fd9c0f6c-5c20-4d95-b3f4-eebca82bea0f ro single echo 'Loading initial ramdisk ...' initrd /boot/initrd.img-2.6.32-31-generic}menuentry 'Ubuntu, with Linux 2.6.32-30-generic' --class ubuntu --class gnu-linux --class gnu --class os { recordfail insmod ext2 set root='(hd0,9)' search --no-floppy --fs-uuid --set fd9c0f6c-5c20-4d95-b3f4-eebca82bea0f linux /boot/vmlinuz-2.6.32-30-generic root=UUID=fd9c0f6c-5c20-4d95-b3f4-eebca82bea0f ro quiet splash initrd /boot/initrd.img-2.6.32-30-generic}menuentry 'Ubuntu, with Linux 2.6.32-30-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os { recordfail insmod ext2 set root='(hd0,9)' search --no-floppy --fs-uuid --set fd9c0f6c-5c20-4d95-b3f4-eebca82bea0f echo 'Loading Linux 2.6.32-30-generic ...' linux /boot/vmlinuz-2.6.32-30-generic root=UUID=fd9c0f6c-5c20-4d95-b3f4-eebca82bea0f ro single echo 'Loading initial ramdisk ...' initrd /boot/initrd.img-2.6.32-30-generic}menuentry 'Ubuntu, with Linux 2.6.32-24-generic' --class ubuntu --class gnu-linux --class gnu --class os { recordfail insmod ext2 set root='(hd0,9)' search --no-floppy --fs-uuid --set fd9c0f6c-5c20-4d95-b3f4-eebca82bea0f linux /boot/vmlinuz-2.6.32-24-generic root=UUID=fd9c0f6c-5c20-4d95-b3f4-eebca82bea0f ro quiet splash initrd /boot/initrd.img-2.6.32-24-generic}menuentry 'Ubuntu, with Linux 2.6.32-24-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os { recordfail insmod ext2 set root='(hd0,9)' search --no-floppy --fs-uuid --set fd9c0f6c-5c20-4d95-b3f4-eebca82bea0f echo 'Loading Linux 2.6.32-24-generic ...' linux /boot/vmlinuz-2.6.32-24-generic root=UUID=fd9c0f6c-5c20-4d95-b3f4-eebca82bea0f ro single echo 'Loading initial ramdisk ...' initrd /boot/initrd.img-2.6.32-24-generic}### END /etc/grub.d/10_linux ###### BEGIN /etc/grub.d/20_memtest86+ ###menuentry "Memory test (memtest86+)" { insmod ext2 set root='(hd0,9)' search --no-floppy --fs-uuid --set fd9c0f6c-5c20-4d95-b3f4-eebca82bea0f linux16 /boot/memtest86+.bin}menuentry "Memory test (memtest86+, serial console 115200)" { insmod ext2 set root='(hd0,9)' search --no-floppy --fs-uuid --set fd9c0f6c-5c20-4d95-b3f4-eebca82bea0f linux16 /boot/memtest86+.bin console=ttyS0,115200n8}### END /etc/grub.d/20_memtest86+ ###### BEGIN /etc/grub.d/30_os-prober ###menuentry "Windows 7 (loader) (on /dev/sda1)" { insmod ntfs set root='(hd0,1)' search --no-floppy --fs-uuid --set de1ca47d1ca45277 chainloader +1}### 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 ###
--------------------------------------------------------------------------------------------------------------------------------------
如上所示，每一个menuentry表示一个启动项，如：
menuentry "Windows 7 (loader) (on /dev/sda1)" {insmod ntfsset root='(hd0,1)'search --no-floppy --fs-uuid --set de1ca47d1ca45277chainloader +1}
表示win7的启动项，处于最后一个(本人计算机共有9个启动项，一般的也可能是7个等等)。若想修改启动项，只需将红色标记的部分中的数字做个修改，如set default="8" 表示默认启动项是列表中的第九个，即本人计算机中的win7系统，“0”表示启动项列表中的第一个。蓝色标记的部分set timeout=10表示留10秒的时间供用户选择。当然了，如果嫌启动项太多太麻烦，只需将menuentry及其后面大括号所包含的部分删除，则相应的启动项就不会在启动时出现。
还可以采取另外一种办法：
将包含win7启动项的部分
### BEGIN /etc/grub.d/30_os-prober ###menuentry "Windows 7 (loader) (on /dev/sda1)" { insmod ntfs set root='(hd0,1)' search --no-floppy --fs-uuid --set de1ca47d1ca45277 chainloader +1}### END /etc/grub.d/30_os-prober ###
整个地放到一下部分的前面：
### BEGIN /etc/grub.d/10_linux ###menuentry 'Ubuntu, with Linux 2.6.32-31-generic' --class ubuntu --class gnu-linux --class gnu --class os { recordfail insmod ext2 set root='(hd0,9)' search --no-floppy --fs-uuid --set fd9c0f6c-5c20-4d95-b3f4-eebca82bea0f linux /boot/vmlinuz-2.6.32-31-generic root=UUID=fd9c0f6c-5c20-4d95-b3f4-eebca82bea0f ro quiet splash initrd /boot/initrd.img-2.6.32-31-generic}。。。。。(在这里省略了)### END /etc/grub.d/10_linux ###
(注：此时 set default="0" 不需要修改，因为此时win7已经排在第一个了，至于其他的很多启动项，反正在后面，不需要管它们。)
最后一种方法 ：
其实不用那么麻烦，要解决启动项问题，你只要新立得安装 startupmanager
“系统”——“系统管理”——“启动管理器” 即可进行设置
不仅可以选择默认启动项，还可以选择等待时间