Ubuntu 开机引导文件 /etc/default/grub

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

# /boot/grub/grub.cfg.

GRUB_DEFAULT=saved

GRUB_SAVEDEFAULT=true

#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_LINUX_RECOVERY="true"

# Uncomment to get a beep at grub start

#GRUB_INIT_TUNE="480 440 1"

对于grub2，ubuntu给了一个官方的配置文件/etc/default/grub。大部分情况下grub2的设置都可以在这个文件中搞定，而且这个文件结构也比较简单，修改起来也容易。完全没有必要直接改/boot/grub/grub.cfg或者/etc/grub.d/下的文件。

修改/etc/default/grub只需简单一个命令：sudo
gedit /etc/default/grub

下面是系统默认的内容，以及最常用的修改菜单显示时间和默认操作系统的方法：

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

# /boot/grub/grub.cfg.

GRUB_DEFAULT=0 #将0改为saved，可让grub记住上次启动时选择的系统

GRUB_HIDDEN_TIMEOUT=0

GRUB_HIDDEN_TIMEOUT_QUIET=true

GRUB_TIMEOUT="5" #显示启动选择菜单的时间

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

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

GRUB_CMDLINE_LINUX=""

# 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 entrys

#GRUB_DISABLE_LINUX_RECOVERY="true"

修改完成后使用命令：

代码:sudo update-grub

会自动更新/boot/grub/grub.cfg，这样做最大的好处是当系统更新内核时，你的设置不会被覆盖掉。

另外对于从9.10 beta及以前一路升级上来的朋友，如果确定想使用grub2，手动运行：

代码:sudo apt-get install grub2

升级并确保grub2正确配置。（我全新安装的9.10 beta，一路升级上来后，系统中的grub工具居然还是老版，运行这个命令后才正常）

其实Ubuntu官方wiki上对这些都有说明：

https://wiki.ubuntu.com/Grub2

PS： 官方文件只说/boot/grub/grub.cfg不要手工修改，这个文件是运行update-grub自动生成的，/etc/default/grub和/etc/grub.d/ (folder)都很重要。

要修改配置文件的只要打开/boot/grub/grub.cfg文件，找到想修改的地方，然后根据注释找到相应的/etc/default/grub或/etc/grub.d/ (folder)进行修改，很方便滴。

File Structure

/boot/grub/grub.cfg This is in keeping with the intent that the file should not be edited manually.

/etc/default/grub

/etc/grub.d/ (folder)