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

1 # If you change this file, run 'update-grub' afterwards to update

2 # /boot/grub/grub.cfg.

3 # For full documentation of the options in this file, see:

4 # info -f grub -n 'Simple configuration'

5

6 GRUB_DEFAULT=7     #更改数字设置默认启动项

7 #GRUB_HIDDEN_TIMEOUT=0

8 GRUB_HIDDEN_TIMEOUT_QUIET=true

9 GRUB_TIMEOUT=10

10 GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`

11 GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

12 GRUB_CMDLINE_LINUX=""

13

14 # Uncomment to enable BadRAM filtering, modify to suit your needs

15 # This works with Linux (no patch required) and with any kernel that obtains

16 # the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...)

17 #GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef"

18

19 # Uncomment to disable graphical terminal (grub-pc only)

20 #GRUB_TERMINAL=console

21

22 # The resolution used on graphical terminal

23 # note that you can use only modes which your graphic card supports via VBE

24 # you can see them in real GRUB with the command `vbeinfo'

25 #GRUB_GFXMODE=640x480

26

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

28 #GRUB_DISABLE_LINUX_UUID=true

29

30 # Uncomment to disable generation of recovery mode menu entries

31 #GRUB_DISABLE_RECOVERY="true"

32

33 # Uncomment to get a beep at grub start

34 #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

1 #

2 # DO NOT EDIT THIS FILE

3 #

4 # It is automatically generated by grub-mkconfig using templates

5 # from /etc/grub.d and settings from /etc/default/grub

6 #

7

8 ### BEGIN /etc/grub.d/00_header ###

9 if [ -s $prefix/grubenv ]; then

10 set have_grubenv=true

11 load_env

12 fi

13 set default="7" #改这个数字设置默认启动项，启动项的特征在下面有标记

14 if [ "${prev_saved_entry}" ]; then

15 set saved_entry="${prev_saved_entry}"

16 save_env saved_entry

17 set prev_saved_entry=

18 save_env prev_saved_entry

19 set boot_once=true

20 fi

21

22 function savedefault {

23 if [ -z "${boot_once}" ]; then

24 saved_entry="${chosen}"

25 save_env saved_entry

26 fi

27 }

28

29 function recordfail {

30 set recordfail=1

31 if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi

32 }

33

34 function load_video {

35 insmod vbe

36 insmod vga

37 insmod video_bochs

38 insmod video_cirrus

39 }

40

41 insmod part_msdos

42 insmod ext2

43 set root='(hd0,msdos7)'

44 search --no-floppy --fs-uuid --set=root dea69c19-08d2-433a-89b9-f917b6d5cce4

45 if loadfont /usr/share/grub/unicode.pf2 ; then

46 set gfxmode=auto

47 load_video

48 insmod gfxterm

49 insmod part_msdos

50 insmod ext2

51 set root='(hd0,msdos7)'

52 search --no-floppy --fs-uuid --set=root dea69c19-08d2-433a-89b9-f917b6d5cce4

53 set locale_dir=($root)/boot/grub/locale

54 set lang=zh_CN

55 insmod gettext

56 fi

57 terminal_output gfxterm

58 if [ "${recordfail}" = 1 ] ; then

59 set timeout=30

60 else

61 set timeout=10

62 fi

63 ### END /etc/grub.d/00_header ###

64

65 ### BEGIN /etc/grub.d/05_debian_theme ###

66 set menu_color_normal=white/black

67 set menu_color_highlight=black/light-gray

68 if background_color 44,0,30; then

69 clear

70 fi

71 ### END /etc/grub.d/05_debian_theme ###

72

73 ### BEGIN /etc/grub.d/10_linux ###

74 function gfxmode {

75 set gfxpayload="${1}"

76 if [ "${1}" = "keep" ]; then

77 set vt_handoff=vt.handoff=7

78 else

79 set vt_handoff=

80 fi

81 }

82 if [ "${recordfail}" != 1 ]; then

83 if [ -e ${prefix}/gfxblacklist.txt ]; then

84 if hwmatch ${prefix}/gfxblacklist.txt 3; then

85 if [ ${match} = 0 ]; then

86 set linux_gfx_mode=keep

87 else

88 set linux_gfx_mode=text

89 fi

90 else

91 set linux_gfx_mode=text

92 fi

93 else

94 set linux_gfx_mode=keep

95 fi

96 else

97 set linux_gfx_mode=text

98 fi

99 export linux_gfx_mode

100 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

112 menuentry 'Ubuntu, with Linux 3.2.0-101-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os {

113 recordfail

114 insmod gzio

115 insmod part_msdos

116 insmod ext2

117 set root='(hd0,msdos7)'

118 search --no-floppy --fs-uuid --set=root dea69c19-08d2-433a-89b9-f917b6d5cce4

119 echo '载入 Linux 3.2.0-101-generic ...'

120 linux /boot/vmlinuz-3.2.0-101-generic root=UUID=dea69c19-08d2-433a-89b9-f917b6d5cce4 ro recovery nomodeset

121 echo '载入初始化内存盘...'

122 initrd /boot/initrd.img-3.2.0-101-generic

123 }

#********************这是一个启动项，启动项2

124 menuentry 'Ubuntu，Linux 3.19.0-68-generic' --class ubuntu --class gnu-linux --class gnu --class os { 125 recordfail 126 gfxmode $linux_gfx_mode 127 insmod gzio 128 insmod part_msdos 129 insmod ext2 130 set root='(hd0,msdos7)' 131 search --no-floppy --fs-uuid --set=root dea69c19-08d2-433a-89b9-f917b6d5cce4 132 linux /boot/vmlinuz-3.19.0-68-generic root=UUID=dea69c19-08d2-433a-89b9-f917b6d5cce4 ro quiet splash $vt_handoff 133 initrd /boot/initrd.img-3.19.0-68-generic134 } 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

来源：https://www.cnblogs.com/hb91/p/5809710.html