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- 1 GRUB
- 1.1 修改GRUB的引导选项Modifying boot options in GRUB
- 1.2 自发现内核列表
- 1.3 Setting kernel parameters
- 1.4 If /boot is on another partition
- 1.5 Changing the Disk that Grub is installed to
- 1.6 Boot splash images
- 1.7 Backup, Repairing and Reinstalling GRUB
- 1.8 Creating a boot floppy
- 1.9 Change the default operating system
- 1.10 Network booting
- 1.11 Security
- 1.12 Windows
- 1.13 More information
- 2 Other Languages
修改GRUB的引导选项Modifying boot options in GRUB
要想进入GRUB的菜单修改引导选项或者选择不同的内核，只需要在它启动后按“ESC”键。在默认配置下，你必须手脚敏捷地按动“ESC”键。如果不想那么狼狈，可以编辑GRUB的配置文件/boot/grub/menu.lst，增加TIMEOUT部分的时间值。或者，你可以要求GRUB在每次启动时都自动打开菜单。要做到这一点，请在“hiddenmenu”前面加上注释号“#”。After pressing 'ESC' you will be presented with a list of kernels and operating systems that you can boot. To modify the boot options highlight the operating system you want to edit and press 'e'. There you will be presented with lines starting with 'root', 'kernel', 'initrd', 'quiet' and 'savedefault'. To receive a more verbose boot process you can remove the 'quiet' line by highlighting it and pressing 'd' to remove that line. You will also need to highlight the 'kernel' line press 'e' to edit and remove the word 'splash' from the end of the line . After making any necessary modifications you can press 'b' to boot that operating system. These modifications will not persist across reboots. If the Ubuntu installer detected other operating systems on the disk during the installation, then the grub menu will be displayed by default and the timeout will be increased, so the step above will be unnecessary.
/boot 下的内核, 并为每一个内核应用全局的设置. 任何时候你一旦更新了内核,
menu.lst "### BEGIN AUTOMAGIC KERNELS LIST" 和 "### END DEBIAN AUTOMAGIC KERNELS LIST" 之间的文本. 注释前至少有两个 '#', 例如： '## this is a comment'. 全局设置以单个 '#' 开头, 例如： '# groot=(hd0,4)'. 我们最常更新的是groot选项，当
/ 目录不在同一个分区上的时候你就需要更改groot选项，关于这一点的更多信息见本页相应的部分. 另一个常见选项是 'kopt=', 该选项应用于所有内核.
Setting kernel parameters
In `/boot/grub/menu.lst`, you will find a line like this:
# kopt=root=/dev/sda1 ro This looks like a comment, but do not remove the '# ' at the beginning. /!\ THIS IS IMPORTANT:
grub sees this line as a comment and ignores it, but it is used as a configuration parameter by
update-grub to generate the contents of the file that
grub will read at boot. If you require additional kernel parameters (for example, if someone has asked you to test booting with certain parameters in order to troubleshoot a problem), add them to the end of the line, for example to add `noapic`:
# kopt=root=/dev/sda1 ro noapic After editing the file, run:
sudo update-grub Note that you can temporarily add kernel parameters at the grub boot menu also, by pressing 'e ' and editing the kernel line.
If /boot is on another partition
/boot is mounted on another partition and you use
update-grub, then you may run into problems. One fix is to use
grub-install, which is a distribution-agnostic way to install the
grub boot loader to a boot sector.
sudo grub-install --root-directory=/boot /dev/sda This is probably less desirable because
update-grub is very good at setting things up properly, therefore it should be used instead. Another fix is to create a symlink in
/boot to itself:
cd /boot sudo ln -s . boot
The reasoning behind this is when grub boots, it looks at whatever partition it is installed on.
grub-install) assumes that everything is in
/boot is on the same partition as
/, then all is OK, as
menu.lst will be in
/boot is on a separate partition, then grub sees
/ (hence the '--root-directory' above). By adding a symlink, when it looks for
/boot/grub, it will be there. By creating the symlink, you have put a loop in the file system, which may cause problems when using certain options of
Changing the Disk that Grub is installed to
Consider the following problem: You have two hard drives, one SATA (/dev/sda), the other PATA (/dev/hda). Your BIOS seems to think that PATA drives should always be booted in preference of SATA drives, but you want to boot from the SATA drive. Grub can work around this problem. Finding groot First, figure out what Grub names the drives. This is listed in
/boot/grub/device.map. There you will find a table of Grub-style names (e.g. (hd0)) and Linux-style names (e.g. /dev/hda/). You need to know what drive and partition
/boot is on. To find where
/boot is, use
df /boot This should tell you the Linux-style partition name where
/boot is. Then simply match it with the Grub-style name in
device.map. This is what groot should be. Example:
$ df /boot Filesystem Size Used Avail Use% Mounted on /dev/sda5 46M 15M 30M 33% /boot $ cat /boot/grub/device.map (hd0) /dev/hda (hd1) /dev/sda
So groot should be (hd1,4) (note that Grub partition numbers are always one less than Linux numbers). Thus in
## default grub root device # groot=(hd1,4)
Finding kernel root The other piece of the puzzle is telling the kernel where
/ is. Simply find out where
/ is mounted.
df / This is what root should be in kopt. Example:
$ df / Filesystem Size Used Avail Use% Mounted on /dev/sda3 14G 8.3G 5.0G 63% /
/ is on
/dev/hda3. Because this is going to be passed to the kernel, there's no need to translate to Grub notation. The 'ro' causes the kernel to mount the drive read-only initially; later the drive will be remounted read/write. This is generally done so
fsck can run on
/ at bootup.
## default kernel options # kopt=root=/dev/sda3 ro
In summary, groot is where
/boot is, and is what Grub sees that drive as. kopt=root is where
/ is, and is what the kernel sees that drive as.
Boot splash images
Grub allows an image to be displayed behind the menu. You can obtain a set of images with the package "grub-splashimages", or you can make your own. The images must be 640x480 pixels, contain no more than 16 colors (but a smaller number like 12 works better to allow some different colors for the menu text), and be in gzipped xpm format. The GIMP can be used to resize (Image -> Scale Image...), reduce colors (Image -> Mode -> Indexed...), and can save to .xpm.gz files.
I'm out of laegue here. Too much brain power on display!
Splash Image with update-grub
The command update-grub will automatically pick up /boot/grub/splash.xpm.gz and configure the menu.lst file for you. It will take care of the correct hdX and partition number [no need to type in (hd0,4)].
sudo apt-get install grub-splashimages sudo ln -s /boot/grub/splashimages/my_image.xpm.gz /boot/grub/splash.xpm.gz sudo update-grub
Note: replace the my_image.xpm.gz with the one that you want.
Backup, Repairing and Reinstalling GRUB
To make a backup a copy of the existing menu.lst file use: cp /boot/grub/menu.lst /boot/grub/menu.lst.old You can try re-installing the grub using the Ubuntu Live CD, in two different ways.
- Boot your computer up with Ubuntu CD
- Go through all the process until you reach "[!!!] Disk Partition"
- Select Manual Partition
- Mount your appropriate linux partions
/ /boot swap .....
5.#5 DO NOT FORMAT THEM.
- Finish the manual partition
- Say "Yes" when it asks you to save the changes
- It will give you errors saying that "the system couldn't install ....." after that
- Ignore them, keep select "continue" until you get back to the Ubuntu installation menu
10. Jump to "Install Grub ...." 11. Once it is finished, just restart your computer
- Boot your computer up with Ubuntu CD
- Open a terminal window or switch to a tty.
- Go SuperUser (that is, type "sudo -s"). Enter root passwords as necessary.
- Type "grub"
- Type "find /boot/grub/stage1". You'll get a response like "(hd1,0)". Use whatever your computer spits out for the following lines.
- Type "root (hd1,0)", or whatever your harddisk + boot partition numbers are for Ubuntu.
- Type "setup (hd1,0)", ot whatever your harddisk nr is.
- Quit grub by typing "quit".
- Reboot and remove the bootable CD.
Creating a boot floppy
You can use grub to create a boot floppy. See BootFloppy
Change the default operating system
By default, Grub in Ubuntu boots Ubuntu by default. If you wish to change this to another operating system, see ChangeDefaultOS
If you use LTSP or Edubuntu, you may want to boot from your network card. Specific network cards need a specifc rom to boot from. To find which one you need, run
lsmod and then search for your floppy. Then go to www.rom-o-matic.com and get the appropriate rom. Edit `/boot/grub/menu.lst` and add the following before
### BEGIN AUTOMAGIC KERNELS LIST or after
### END DEBIAN AUTOMAGIC KERNELS LIST, otherwise your changes will be wiped out by security updates, etc.
title LTSP root (hd0,2) kernel /boot/(rom you get from rom-o-matic)
By editing the boot command in grub, root access can be gained without the need of a password. To avoid this, edit the part "## password ['--md5'] passwd" of `/boot/grub/menu.lst`:
Insert the password of your choice. To prevent normal users to read this password, you should also remove read permission for these:
sudo chmod o-r /boot/grub/menu.lst
You can also use a md5 password, more info in the Gentoo Security Handbook.
- The official GNU GRUB manual has a "DOS/Windows" chapter with hints on setting up dual-boot systems.
- This page has a lot of Grub information (and other general information).
- Reinstall Ubuntu Grub Bootloader After Windows Wipes it Out
- Installing GRUB using grub-install
- How To Repair your GRUB