ubuntu更改启动顺序

在ubuntu中修改启动配置。

启动相关grub2主要包含下面三个文件：1.   /boot/grub/grub.cfg 文件    2.   /etc/grub.d/ 文件夹   3.   /etc/default/grub 文件，可以通过修改这三个文件来修改启动项

链接：http://blog.csdn.net/zhu_liangwei/article/details/7847034

一

更改启动顺序，验证过的两种方式

1、修改 /etc/default/grub 文件

打开文件

sudo gedit /etc/default/grub

修改文件

GRUB_DEFAULT=0     #更改数字设置默认启动项

更新

sudo update-grub

 # If you change this file, run 'update-grub' afterwards to update
 # /boot/grub/grub.cfg.
 # For full documentation of the options in this file, see:
 #   info -f grub -n 'Simple configuration'

 GRUB_DEFAULT=7     #更改数字设置默认启动项
 #GRUB_HIDDEN_TIMEOUT=0
 GRUB_HIDDEN_TIMEOUT_QUIET=true
 GRUB_TIMEOUT=10
 GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
 GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
 GRUB_CMDLINE_LINUX=""

 # Uncomment to enable BadRAM filtering, modify to suit your needs
 # This works with Linux (no patch required) and with any kernel that obtains
 # the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...)
 #GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef"

 # Uncomment to disable graphical terminal (grub-pc only)
 #GRUB_TERMINAL=console

 # The resolution used on graphical terminal
 # note that you can use only modes which your graphic card supports via VBE
 # you can see them in real GRUB with the command `vbeinfo'
 #GRUB_GFXMODE=640x480

 # Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux
 #GRUB_DISABLE_LINUX_UUID=true

 # Uncomment to disable generation of recovery mode menu entries
 #GRUB_DISABLE_RECOVERY="true"

 # Uncomment to get a beep at grub start
 #GRUB_INIT_TUNE="480 440 1"

配置文件详解 http://lesca.me/archives/manage-grub2-config-file.html

二

修改 /boot/grub/grub.cfg文件，使用sudo update-grub会被覆盖掉。

打开文件

sudo gedit /boot/grub/grub.cfg

修改文件

set default = '0'   修改数字

 #
 # DO NOT EDIT THIS FILE
 #
 # It is automatically generated by grub-mkconfig using templates
 # from /etc/grub.d and settings from /etc/default/grub
 #

 ### BEGIN /etc/grub.d/00_header ###
 if [ -s $prefix/grubenv ]; then
   set have_grubenv=true
   load_env
 fi
 set default=""    #改这个数字设置默认启动项，启动项的特征在下面有标记
 if [ "${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=true
 fi

 function 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
 }

 function load_video {
   insmod vbe
   insmod vga
   insmod video_bochs
   insmod video_cirrus
 }

 insmod part_msdos
 insmod ext2
 set root='(hd0,msdos7)'
 search --no-floppy --fs-uuid --set=root dea69c19-08d2-433a-89b9-f917b6d5cce4
 if loadfont /usr/share/grub/unicode.pf2 ; then
   set gfxmode=auto
   load_video
   insmod gfxterm
   insmod part_msdos
   insmod ext2
   set root='(hd0,msdos7)'
   search --no-floppy --fs-uuid --set=root dea69c19-08d2-433a-89b9-f917b6d5cce4
   set locale_dir=($root)/boot/grub/locale
   set lang=zh_CN
   insmod gettext
 fi
 terminal_output gfxterm
 if [ "${recordfail}" = 1 ] ; then
   set timeout=30
 else
   set timeout=10
 fi
 ### END /etc/grub.d/00_header ###

 ### BEGIN /etc/grub.d/05_debian_theme ###
 set menu_color_normal=white/black
 set menu_color_highlight=black/light-gray
 if background_color 44,0,30; then
   clear
 fi
 ### END /etc/grub.d/05_debian_theme ###

 ### BEGIN /etc/grub.d/10_linux ###
 function gfxmode {
     set gfxpayload="${1}"
     if [ "${1}" = "keep" ]; then
         set vt_handoff=vt.handoff=7
     else
         set vt_handoff=
     fi
 }
 if [ "${recordfail}" != 1 ]; then
   if [ -e ${prefix}/gfxblacklist.txt ]; then
     if hwmatch ${prefix}/gfxblacklist.txt 3; then
       if [ ${match} = 0 ]; then
         set linux_gfx_mode=keep
       else
         set linux_gfx_mode=text
       fi
     else
       set linux_gfx_mode=text
     fi
   else
     set linux_gfx_mode=keep
   fi
 else
   set linux_gfx_mode=text
 fi
 export linux_gfx_mode
 if [ "${linux_gfx_mode}" != "text" ]; then load_video; fi
#********************这是一个启动项，启动项0，红色的是启动项名字
101 menuentry 'Ubuntu，Linux 3.2.0-101-generic' --class ubuntu --class gnu-linux --class gnu --class os {
102     recordfail
103     gfxmode $linux_gfx_mode
104     insmod gzio
105     insmod part_msdos
106     insmod ext2
107     set root='(hd0,msdos7)'
108     search --no-floppy --fs-uuid --set=root dea69c19-08d2-433a-89b9-f917b6d5cce4
109     linux    /boot/vmlinuz-3.2.0-101-generic root=UUID=dea69c19-08d2-433a-89b9-f917b6d5cce4 ro   quiet splash $vt_handoff
110     initrd    /boot/initrd.img-3.2.0-101-generic
111 }

#********************这是一个启动项，启动项1
 menuentry 'Ubuntu, with Linux 3.2.0-101-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os {
     recordfail
     insmod gzio
     insmod part_msdos
     insmod ext2
     set root='(hd0,msdos7)'
     search --no-floppy --fs-uuid --set=root dea69c19-08d2-433a-89b9-f917b6d5cce4
     echo    '载入 Linux 3.2.0-101-generic ...'
     linux    /boot/vmlinuz-3.2.0-101-generic root=UUID=dea69c19-08d2-433a-89b9-f917b6d5cce4 ro recovery nomodeset
     echo    '载入初始化内存盘...'
     initrd    /boot/initrd.img-3.2.0-101-generic
 }

#********************这是一个启动项，启动项2

 menuentry 'Ubuntu，Linux 3.19.0-68-generic' --class ubuntu --class gnu-linux --class gnu --class os { 
  recordfail 
  gfxmode $linux_gfx_mode 
  insmod gzio 
  insmod part_msdos 
  insmod ext2 
 set root='(hd0,msdos7)' 
 search --no-floppy --fs-uuid --set=root dea69c19-08d2-433a-89b9-f917b6d5cce4 
 linux /boot/vmlinuz-3.19.0-68-generic root=UUID=dea69c19-08d2-433a-89b9-f917b6d5cce4 ro quiet splash $vt_handoff 
 initrd /boot/initrd.img-3.19.0-68-generic
 } 

后边的代码太多删了
submenu "Previous Linux versions" 算一个，在启动时选择该项，能选择里面的启动内核

谨慎修改grub