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Thread: Grub 2 Basics

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    Grub 2 Basics

    This page has been migrated to the Ubuntu Community Documentation site. For the most up-to-date information, please visit:
    https://help.ubuntu.com/community/Grub2

    On that page are links to a variety of other Grub 2 pages which cover installation, troubleshooting, ISO booting, Grub menu displays, and more. The majority of those pages were migrated from threads started on the Ubuntu Forums.

    Thank you to all the users who posted in these threads and expanded our knowledge of Grub 2 since it's introduction.

    A thread for discussion of the wiki can be found at http://ubuntuforums.org/showthread.php?p=12073029


    Support threads regarding the wiki and it's content should be created in a suitable forum.

    The Grub 2 Guide
    (formerly Grub 2 Basics)


    Better Documentation - Get It From the Grub 2 Developers
    This thread is more than two years old. It was written at a time when Grub 2 was very new and there was very little documentation for end users. Fortunately, over time, the documentation has been greatly improved and GUI apps have been developed to assist users. Two important sources of Grub 2 information are the GNU Grub Manual and on-line information available by running the following command:
    Code:
    info -f grub -n 'Simple configuration'

    Grub 1.99 / Natty: Black Screen, with or without blinking cursor
    If your boot in Natty ends up at a blank black screen, or a screen with a blinking cursor, take a look at the following thread. Forum member MAFoElffen has done some great research and has come up with some workarounds that may get your system booted. Here is the thread:
    Graphics Resolution- Upgrade /Blank Screen after reboot


    Repair Using the Correct CD !
    It appears that Grub 1.98 and Grub 1.99 don't get along well. If having to repair a Grub 2 problem using a LiveCD, make sure the OS and CD are for the same release (Natty LiveCD for Natty, Maverick LiveCD for Maverick, etc). This includes running the 'grub-install' command to write to the MBR.

    Grub 1.99 Changes - A Brief Look
    http://ubuntuforums.org/showthread.php?p=10720322


    Grub 1.99: Error: No Argument Specified, and Error: Invalid Signature.

    While menuentries generated with Grub 1.99 work correctly, menuentries from older custom menus or imported from earlier Grub 2 menus may produce the above errors. The reason is a format change to the "set" section of the 'search' line.
    Old:
    search --no-floppy --fs-uuid --set d789eb41-eaff-458c-be34-0e2f9b414f1e
    New (for Grub 1.99 / Natty only):
    search --no-floppy --fs-uuid --set=root d789eb41-eaff-458c-be34-0e2f9b414f1e

    New for Natty - Grub 1.99 (RC) - Drag & Drop GRUB Background
    For Ubuntu 11.04 Natty and Grub 1.99RC: Place a graphic in /boot/grub, run update-grub and you should have a Grub menu background image. Read more in this thread:
    Grub 2 Drop-In Backgrounds & Fonts


    GUI Apps for Grub 2 - Finally some apps for the GUI enthusiast!
    Grub Customizer - Daniel Richter has developed a graphical Grub2 configuration application. It's an excellent step in making Grub2 menu changes simpler for the average user. It provides users with a method of altering their Grub2 menus without using the command line and obscure commands. The application is available from this Launchpad page. How it works is detailed in this FAQ. Here is the Ubuntu Forum HOWTO on Grub Customizer:
    Grub Customizer

    Boot Repair - Forum member YannBuntu has developed an app which helps repair the MBR or purge and restore Grub 2 without having to use the terminal extensively. If a terminal command is required, the app tells you what it is. Here is the forum link:
    [Boot-Repair] Graphical tool to repair the PC boot in 1 clic !

    Thanks to Daniel and YannBuntu for providing these apps to the Ubuntu community.

    GRUB Changes to /etc/default/grub Options
    Grub 1.98 has made some changes, and Grub 1.99 is making more to the options available in /etc/default/grub. To see the current options available to /etc/default/grub for your version:
    Code:
    grep "export GRUB_DEVICE" -A42 /usr/sbin/grub-mkconfig
    For instance, in Grub 1.98 and earlier, the /etc/default/grub entry to hide "Recovery" menu entries was "GRUB_DISABLE_LINUX_RECOVERY=true". In G2 1.99 it is currently "GRUB_DISABLE_RECOVERY=true".


    Wubi Megathread Guide
    Having problems with your Wubi installation? Forum member Rubi1200 has written an excellent comprehensive guide on resolving Wubi-related problems. View the "Wubi Megathread" at http://ubuntuforums.org/showthread.php?t=1639198


    Grub Submenu
    Test versions of Ubuntu 11.04 (Natty Narwhale) are being released with Grub 1.99. One of the new features is the use of the Submenu. The submenu is still being tweaked, but should hide older kernels in the main OS. Clicking on the Submenu entry will reveal the underlying older kernels. Using a Submenu kernel as the default initially was not possible, but a patch has been submitted by Colin Watson. The user will be able to use either the exact menuentry title or the "saved" function in /etc/default/grub's GRUB_DEFAULT= setting to set a submenu default. The use of a number in GRUB_DEFAULT is currently not possible. More details as they become available.



    1. Introduction
    2. First Look Differences
    3. Improvements
    4. Booting Grub
    5. Grub 2 Files & Options
    6. Adding Entries to Grub 2
    7. Removing Entries from Grub 2
    8. Grub 2 Splash Images & Theming
    9. Changing Menu Resolution
    10. Password Protection
    11. Booting to Recovery Mode w/o Menu Option
    12. Uninstalling GRUB 2 > GRUB
    13. Reinstalling GRUB 2 from the LiveCD
    14. Booting to LiveCD ISO
    15. Booting from the Rescue Mode
    16. Restoring GRUB2 / XP / Vista / Win 7 Bootloaders
    17. Grub Rescue Image
    18. Grub 2 Fallback Option
    19. Selected Problems & Bugs
    20. Links


    1. Introduction
      I've written this guide to present some basic information about Grub 2, now the default bootloader on all supported Ubuntu Desktops. There are now versions 1.97~beta, 1.98 (Lucid/Maverick) and 1.99 (Natty), with improvements (and file changes) in each subsequent version. Since Lucid is the LTS, references to Grub 2 will refer to 1.98 unless otherwise noted. The user can check their current version with the "grub-install -v" command.

      Grub 2 GUI Apps: There are currently 3 GUI apps which support Grub 2. This guide primarily deals with the terminal and editing files, since the thread was originally created when there was little to no support for Grub 2.
      Startup Manager: Provides basic support for Grub 2 but not all options are available. The two most-used items, however, are: setting the default kernel/OS and setting the menu timeout delay. View the StartUpManager community doc or the forum post on which it was based: http://ubuntuforums.org/showthread.php?t=818177
      Grub Customizer: Designed by Daniel Richter for Grub 2 with a good variety of customization options. Here is a guide on installing and using GC:
      Grub Customizer
      Boot Repair: A boot and Grub 2 repair app created by YannBuntu. Repair the MBR and purge/reinstall Grub 2 assistance.
      Boot-Repair


      Official documentation for Grub 2 has been greatly expanded since it's release. The source document should take precedence over material found in this thread, unless otherwise noted. This link is to Grub 1.99:
      http://www.gnu.org/software/grub/manual/grub.html

      For troubleshooting and modifying the Grub menu, it is important to know which version you are using (Grub legacy, 0.97; Grub 2 in Karmic 1.97~beta4; Grub 2 in Lucid 1.98, 1.99RC in Natty). To confirm the version of Grub used in your system, run this command:
      Code:
      grub-install -v
      Which should produce something like this:
      drs305@mycomputer:~$ grub-install -v
      grub-install (GRUB) 1.98+20100804-5ubuntu3
    2. First Look Differences: GRUB vs GRUB 2
      At first boot, there will not be much difference in what the user sees on the boot menu. The one exception is a clean install of Ubuntu with no other installed operating system(s). In this case, GRUB 2 will boot directly to the login prompt or Desktop without displaying a menu. Other major differences:
      • No ''/boot/grub/menu.lst''. It has been replaced by ''/boot/grub/grub.cfg''.
      • Hold down SHIFT to display the hidden menu during boot (formerly ESC is GRUB legacy).
      • There is no "find /boot/grub/stage1" at the grub prompt. Stage 1.5 has also been eliminated.
      • The main menu file, ''/boot/grub/grub.cfg'' is not normally edited directly, as it will be overwritten by certain updates (see next).
      • ''grub.cfg'' is overwritten when there is a Grub update, a kernel is added/removed or the user runs `update-grub` *
      • A pre-made custom file, ''/etc/grub.d/40_custom'', is available in which users can place their own entries. This file will not be overwritten by Grub updates.
      • The primary configuration file for changing menu display settings is ''/etc/default/grub''.
      • There are multiple files for configuring the the menu - ''/etc/default/grub'' mentioned above, and all the scripts in /etc/grub.d/ folder.
      • Other operating systems, such as Windows, should automatically be recognized and added to the menu.
      • No changes made in the configuration files will take effect until the `update-grub` command is also run.
      • Grub 1.99 Changes: This version introduces submenu and drop-in background image capabilities. Read more at: Grub 1.99 Changes

      * To update the GRUB 2 menu, the command sudo update-grub will be used throughout this guide. update-grub actually runs the command "grub-mkconfig -o /boot/grub/grub.cfg" This runs several scripts and incorporates the results into /boot/grub/grub.cfg which detemines what is seen on the screen during boot. Since the GRUB 2 developers do not intend to remove the update-grub 'stub', it will be used for simplicity and ease of use.

    3. Improvements
      GRUB 2's major improvements over the original GRUB include:
      • New configuration file structure
      • Scripting support including conditional statements and functions
      • Dynamic module loading
      • Rescue mode
      • Themes - under (very slow development). Users wishing to use theming should search the Internet for "burg".
      • Graphical boot menu support and improved splash capability
      • Boot Ubuntu LiveCD and some other ISO images directly from hard drive
      • Non-X86 platform support (such as PowerPC)
      • Universal support for UUIDs (not just Ubuntu)
      • Improved internationalization, including support for non-ASCII characters


    4. Booting Grub
      Grub 2 loads before the operating system. It's modular components are loaded on an as-needed basis. Menu display behavior is generally determined by settings in /etc/default/grub. Review the "Grub 2 Files & Options" section for specific entry and formatting guidance.

      The main options for displaying the menu are:
      • Initial Default
        • Grub 2 will boot straight into the default operating system if no other operating system is detected. No menu will be displayed. If another operating system is detected, the Grub 2 menu will display.

      • Timed display.
        • The default delay is 10 seconds. If no user input is made Grub 2 boots to the default entry.
        • The countdown can be stopped by pressing any key. The user must then make a selection manually.
        • The booted entry is determined by the DEFAULT= setting in /etc/default/grub, The first "menuentry" is 0.

      • Hidden
        • The user can interrupt the boot process and display the menu by holding down the SHIFT key until the menu displays. Grub 2 searches for a depressed SHIFT key signal during boot. If the key is pressed or Grub 2 cannot determine the status of the key, the menu is displayed. Note: The "SHIFT" keystatus check is currently nested within in a conditional statement within /etc/grub.d/30_os-prober and may not work under certain circumstances.
        • The time the screen remains blank but available for display is determined by a setting in /etc/default/grub.
        • To provide visual feedback during while the countdown continues, a countdown display can be shown on the screen.
        • At the end of the timeout, the default entry determined in /etc/default/grub will be selected.

      • Saved
        • If the default option is set to "saved", the last kernel/system successfully booted will be selected and run if no input is made.
        • Unlike GRUB, GRUB 2 stores the "saved" entry as a string, not as a menu position number. In GRUB 2, the result is applied more consistently. Example: If the first entry (kernel -15) becomes the second entry due to a kernel update, it will still be the "saved" entry even though it's position on the menu has changed.


    5. Grub 2 Files & Options
      Many of the files in /boot/grub will not be recognizable by users of Grub Legacy. Especially noticeable are the multitude of *.mod files. Grub 2 is modular and these files are loaded as necessary by the grub bootloader.

      The Grub 2 user-configurable settings are contained mainly in /etc/default/grub and the files in /etc/grub.d. When update-grub is executed the results are input into the /boot/grub/grub.cfg file.

      • /boot/grub/grub.cfg
        • This is the main Grub 2 file. It "replaces" Grub Legacy's /boot/grub/menu.lst This file contains the Grub menu information but unlike Grub Legacy's menu.lst file, grub.cfg is not normally meant to be edited as it is the product of Grub2 configuration scripts and is overwritten during certain updates. If a user edits grub.cfg, expect the changes to be removed during such updates or disable the ability of the OS to run these updates.
          • grub.cfg is automatcially generated when "update-grub" is executed:
          • Each section (### BEGIN) is clearly delineated and references the file in the /etc/grub.d folder from which the information was generated. The major default sections are 00_header, 05_debian_theme, 10_linux, 30_os-prober, and 40_custom.
          • grub.cfg is updated by running the "update-grub" or "update-grub2" command as root.
          • By default, and whenever the "update-grub" command is executed, this file is made "read-only". This is in keeping with the intent that the file should not be edited manually. If you must edit this file, instructions are provided in Section 2.

      • /etc/default/grub
        Note: Online documentation regarding the options available in this file is available by running the following command in a terminal:
        Code:
        info -f grub -n 'Simple configuration'
        • This file contains information formerly contained in the upper section of Grub Legacy's menu.lst and items contained on the end of the kernel line. The items in this file can be edited by a user with administrator (root) privileges.
        • To find the options available in a specific version of Grub 2, open a terminal and run: grep "DEVICE" -A 40 /usr/sbin/grub-mkconfig
          # If you change this file, run 'update-grub' afterwards to update
          # /boot/grub/grub.cfg.

          GRUB_DEFAULT=0
          #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 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"

      • GRUB_DEFAULT - Sets the default menu entry. Entries may be numeric or "saved"
        • GRUB_DEFAULT=0 - Sets the default menu entry by menu position. As Grub Legacy, the first "menuentry" in grub.cfg is 0, the second is 1, etc.
        • GRUB_DEFAULT=saved - (Grub 1.98) Enables the "grub-reboot" and "grub-set-default" commands.
          • This setting allows the use of the following commands to set a default OS. The default OS will not be set merely by an interactive selection of an OS from the menu.
          • grub-set-default. Sets the default boot entry until changed.
            • The format is "sudo grub-set-default X, with X being the menuentry position (starting with 0 as the first entry) or the exact menu string. Examples: sudo grub-set-default 3 or sudo grub-set-default "Ubuntu, Linux 2.6.32-15-generic"
            • To obtain the existing menuentry choice number (starting from 0) or the menuentry "string", run "grep menuentry /boot/grub/grub.cfg"

          • grub-reboot. This command sets the default boot entry for the next boot only. The format of the command is the same as for "grub-set-default" (see above).
          • For an example of how to enable the "saved" option with a custom menu, see the "Custom User Entries" section.

        • GRUB_DEFAULT="xxxx" - An exact menu entry, including the quotation symbols, may also be used. In this case, location in the menu will not matter. Example: GRUB_DEFAULT="Ubuntu, Linux 2.6.31-9-generic"

      • GRUB_SAVEDEFAULT=true * If set to true this setting will automatically set the last selected OS from the menu as the default OS on the next boot. No commands need be run to set the default OS. For this entry to work, the GRUB_DEFAULT entry should be set to saved.
      • GRUB_TIMEOUT=10 - No change from Grub Legacy. This is the number of seconds before the default entry is automatically booted.
        • Setting this value to -1 will cause the menu to display until the user makes a selection.
        • To display the menu on each boot use a value of 1 or higher.
        • This command defers to the GRUB_HIDDEN_TIMEOUT command. If the GRUB_HIDDEN_TIMEOUT option is interrupted by pressing the SHIFT key, the GRUB_TIMEOUT counter begins its countdown.
        • Caution: Holding down the "SHIFT" key will not display the menu if "GRUB_TIMEOUT=" is set to "0" .
        • In addition to editing the file as root, you can also run the following commands the check and change the default timeout value. The first checks the existing timeout, the second replaces the value. Replace T with the new value.
          Code:
          cat /etc/default/grub | grep 'GRUB_TIMEOUT='   # Checks current TIMEOUT value.
          sudo sed 's/GRUB_TIMEOUT=10/GRUB_TIMEOUT=T/g' -i /etc/default/grub  # Change TIMEOUT value. Replace T with new value.

      • GRUB_HIDDEN_TIMEOUT=0
        • Wait X seconds for a key to be pressed before displaying the menu. If no key is pressed during that time, boot immediately.


      • GRUB_HIDDEN_TIMEOUT_QUIET=true
        • Used with the GRUB_HIDDEN_TIMEOUT setting.
        • true - No countdown is displayed. The screen will be blank.
        • false - A counter will display on a blank screen for the duration of the GRUB_HIDDEN_TIMEOUT value.
        • This feature currently appears to be broken; the timeout counter isn't appearing when set to 'false' or not set.

      • GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
        • Determines the descriptive name in the menu entry. (Ubuntu, Xubuntu, Debian, etc.)

      • GRUB_CMDLINE_LINUX
        If it exists, this line imports any entries to the end of the 'linux' command line (Grub Legacy's "kernel" line) for both normal and recovery modes. This is similar to the "altoptions" line in menu.lst
      • GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
        This line imports any entries to the end of the 'linux' line (Grub Legacy's "kernel" line). The entries are appended to the end of the normal mode only. This is similar to the "defoptions" line in menu.lst. For a black screen with boot processes displayed in text, remove "quiet splash". To see the grub splash image plus a condensed text output, use "splash". This line is where other instructions, such as "acpi=off" are placed.

        For the GRUB_CMDLINE_LINUX_DEFAULT and GRUB_CMDLINE, quotation marks are required (single or double) if the entry is more than one alphanumeric entry. For example, quiet splash requires single or double quotes, while an entry such as quiet would not.
      • #GRUB_TERMINAL=console
        Uncomment to disable graphical terminal (grub-pc only). This can be useful if the user plans on spending a lot of time in the GRUB 2 command line mode. Scrolling and screen responsiveness will be greatly speeded up. If enabled, Grub background splash images will not be displayed.
      • #GRUB_DISABLE_LINUX_UUID=true
        Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux
        Update: A bug requires quotation symbols be added for this option to be enabled. Change true to "true" and uncomment the line to eliminate UUIDs for linux entries.
      • #GRUB_GFXMODE=640x480
        You can add this line and remove the # symbol to make it active. This entry sets the resolution of the graphical menu (the menu text size). It provides resolutions supported by the user's graphics card (e.g. 640x480, 800x600, 1280x1024, etc). The setting applies only to the boot menu text.
      • From the GRUB 2 menu you can display available resolutions by typing "c" and then at the "grub>" prompt type "vbeinfo"
      • GRUB_DISABLE_LINUX_RECOVERY=true (GRUB 1.98 & earlier) or GRUB_DISABLE_RECOVERY=true (GRUB 1.99 & later)

        Add or uncomment this line to prevent "Recovery" mode kernel options from appearing in the menu. If you want a "Recovery" option for only one kernel, make a special entry in /etc/grub/40_custom.
      • GRUB_DISABLE_OS_PROBER="true" * Enables/disables the os-prober check of other partitions for operating systems, including Windows, Linux, OSX and Hurd.
      • GRUB_INIT_TUNE="480 440 1"
        • Introduced in Grub 1.98 (Lucid)
        • When uncommented, plays a single beep just prior to the Grub 2 menu display.
        • The format unless a file is named is: "tempo [pitch1 duration1] [pitch2 duration2] ..."
        • The duration is based on the tempo. A tempo of 60 gives the duration a value of 1 second, 120 is .5, 240 is .25, 480 is .125, etc. The length of the tone can be changed by modifying either the tempo (all tones) or duration (individual tone).
          • Just a bit of fun:
            • Warning: The menu will not be displayed until the tone is finished
            • Close Encounters/5 Tone: GRUB_INIT_TUNE="480 900 2 1000 2 800 2 400 2 600 3"
            • Fur Elise (note long): GRUB_INIT_TUNE="480 420 1 400 1 420 1 400 1 420 1 315 1 370 1 335 1 282 3 180 1 215 1 282 1 315 3 213 1 262 1 315 1 335 3 213 1 420 1 400 1 420 1 400 1 420 1 315 1 370 1 335 1 282 3 180 1 215 1 282 1 315 3 213 1 330 1 315 1 282 3"


        • Online documentation is available by typing "info grub --index-search play" in a terminal.

        * Entries which are not found in the default file and must be added by the user.
      • /etc/grub.d/
        • The files in this folder are read during execution of "update-grub" or "update-grub" commands. The contents are imported into /boot/grub/grub.cfg

          The order of the entries in the grub menu is based on the order of the file names. File named with a starting numeral are run before those beginning with a letter. The order the files are run determines the menu order in grub.cfg.
          Custom entries can be added to the "40_custom" file or in a newly created file.

          Any file created must be executable in order to be included in the grub.cfg file during the "update-grub" command.
          • 00_header
          • 05_debian_theme: Set background and text colors, themes
          • 10_hurd Locates Hurd kernels
          • 10_linux Locates Linux kernels based on results of the "lsb_release" command.
          • 10_lupin Locates Linux kernels in Wubi installs within Windows, among other things.
          • 20_memtest86+: If the file /boot/memtest86+.bin exists, it is included as a menu item.
          • 30_os-prober: Searches for Linux and OS's on other partitions and includes them in the menu.
          • 40_custom: A template for adding custom menu entries which will be inserted into grub.cfg upon execution of the "update-grub" command. This and any other custom file must be made executable to allow importation into grub.cfg.


    6. Adding Entries to Grub 2
      Menu entries can be added to grub.cfg automatically or manually.
      • Automatically.
        • When "update-grub" is executed, Grub 2 will search for linux kernels and other Operating Systems. What and where is looks is based on the files contained in /etc/grub.d folder.
          • 10_linux searches for installed linux kernels on the same partition.
          • 30_os-prober searches for other operating systems.


      • Custom User Entries (/etc/grub.d/40_custom).
        • Entries to grub.cfg can be manually inserted by creating a file in the /etc/grub.d folder.
          • The name of the file determines the order in the menu. 30_os-prober entries will be placed before 40_custom entries, which will be placed before 50_my-sample entries.
          • Any created file must be made executable. This can be done as root by running "sudo chmod +x /etc/grub.d/filename".
          • The files in the /etc/grub.d folder will be read and the contents included in grub.cfg when the "update-grub" command is executed as root.

        • A sample entry. This file creates a menu item for running the SystemRescueCD (previously installed) from a partition created on sda10. Folders and files must have been copied to the correct location in accordance with the SystemRescueCD if you wish to actually use this entry. Note this entry will not work for a SystemRescue ISO. See Section 14 for instructions on how to add an entry to boot ISO images.
          • #!/bin/sh
            exec tail -n +3 $0
            # 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.

            menuentry "System Rescue CD" {
            set root=(hd0,10)
            linux /sysrcd/rescuecd subdir=sysrcd setkmap=us
            initrd /sysrcd/initram.igz
            }
          • Note the new partition naming convention. Devices start counting from "0" as done previously. sda is designated as "hd0", sdb is "hd1", etc. However the first partition is now designated as sda1. Counting partitions does not start with "0". sda5 is "5".
          • If the user wishes to get visual confirmation in the terminal that the 40_custom file contents are being added when "update-grub" is executed, the following line can be added to the /etc/grub.d/40_custom file:
            • echo "Adding 40_custom menu entries." >&2
            • Place this line immediately after the first line - "#!/bin/bash" - and before the "exec tail -n +3 $0" line.


        • Tip: If you want to have your custom entries at the top of the menu (say you want custom titles), create a new file and name it "07_xxxx". Since the files in /etc/grub.d/ are read sequentially, those in "07_custom" will be placed before those of "10_linux". I recommend not naming a custom menu file lower than 06 so that any theme run from 05_debian_theme is allowed to run before any custom menu is created. After creating the file, run sudo update-grub and then check the value of "DEFAULT" in /etc/default/grub. If it doesn't point to the correct menuentry, change the value of DEFAULT to the correct menuentry value.
        • Omitting memtest86+: To prevent "memtest86+" entries in your Grub 2 menu, remove the "executable" bit from /etc/grub.d/20_memtest86+. You can do this via a file browser by selecting "Properties (right click), Permissions", or via the command line:
          Code:
          sudo chmod -x /etc/grub.d/20_memtest86+
        • Omitting Recovery Mode entries: The file /etc/grub.d/10_linux was recently updated to include a check for recovery mode options. Edit /etc/default/grub and add or change this line:
          GRUB_DISABLE_LINUX_RECOVERY=true # GRUB 1.98 & earlier
          GRUB_DISABLE_RECOVERY=true # GRUB 1.99 & later
          If you have an older version of /etc/grub.d/10_linux and the above does not work after updating grub, you can prevent "Recovery mode" entries in your Grub 2 menu, by editing /etc/grub.d/10_linux. If there are no conditional "if" statements concerning the recovery mode, place a comment symbol (#) in front of the following lines (at approximately line 146) of the old file:
          # linux_entry "${OS}, Linux ${version} (recovery mode)" \
          # "single ${GRUB_CMDLINE_LINUX}"
          If you wish to retain one "Recovery mode" entry for insurance, you can add an entry to /etc/grub.d/40_custom which will appear at the bottom of your grub menu.
        • Building a Totally Customized Menu: Ok, admit you are a control freak and you want to see only what you build yourself - customized titles, no "memtest86+" and no extra kernels. Here is how you do it:
          • Run sudo update-grub to get the current available kernels.
          • Copy the desired "menuentry" listings from /boot/grub/grub.cfg to /etc/grub.d/40_custom The entry begins with the line starting with "menuentry" and ends with a line containing "}".
          • Add any other "menuentry" items you wish to see on the boot menu.
          • Edit the titles of the "menuentry" line if desired (between the quotation symbols). Do not change the lines following the "menuentry" line. Each entry should start with a "menuentry" line and end with a "}" on the last line.
          • Remove the executable bit from /etc/grub.d/10_linux, /etc/grub.d/20_memtest86+ and /etc/grub.d/30_os-prober
            Removing the executable bit from any file in /etc/grub.d will exclude the file from being included in grub updates.
            Code:
            sudo chmod -x /etc/grub.d/10_linux /etc/grub.d/20_memtest86+ /etc/grub.d/30_os-prober
          • Run "sudo update-grub"
          • The updated /boot/grub/grub.cfg file should now contain only sections for "00_header", "05_debian_theme" and "40_custom".
          • The grub.cfg file will not be updated with the addition of a new kernel. To add a new kernel, make "10_linux" executable, run "sudo update-grub" to refresh the available kernels, and repeat these instructions.

        • Don't forget to run "sudo update-grub" after making any changes to your /etc/grub.d files.


      • Manual Editing of grub.cfg
        Manual editing of /boot/grub/grub.cfg is not normally encouraged, as it can be overwritten by system operations and updates. grub.cfg is created by various Grub2 scripts, and it is usually preferable to edit the content of the scripts so the changes are retained during updates. The files that should be edited are contained in the /etc/grub.d folders and the /etc/default/grub file. Users making changes to grub.cfg should recognize these changes may be overwritten or should disable the ability of the system to update the grub.cfg file.

        In order to discourage its editing, grub.cfg is read-only. If you must edit this file:
        Code:
        gksudo gedit /boot/grub/grub.cfg
        Note: This file is returned to 'read-only' status anytime the update-grub command is run.


    7. Removing Entries from Grub 2
      Entries should be removed by editing or removing files in the /etc/grub.d folder. The /boot/grub/grub.cfg file is read-only and should not normally require editing.

      • Automatically.
        • Too Many Kernels?
          • If you are not sure of the kernel you are currently using, in a terminal type "uname -r".
          • Kernels removed via APT (Synaptic, "apt-get remove", etc.) will automatically update grub.cfg and no user action is required. A great tool for removing kernels (and menu entries) is Ubuntu-Tweak, a safe and easy-to-use GUI app.
          • Many users keep one previous kernel known to work on the machine as a backup.
            • Synaptic
              • Type the kernel number in the search window at the upper right (for example - 2.6.28-11).
              • Find the "linux-image" and "linux-headers" files for the applicable kernel (example - linux-image-2.6.26-11 or "linux-image-2.6.26-11-generic).
              • Right click and select "Mark for Complete Removal" and then press the Apply main menu button.
              • The kernels will be removed from your system and from the Grub menu.

            • Ubuntu-Tweak
              • Go to the Ubuntu-Tweak download page.
              • Add the repository as per the instructions, or download the file manually and double-click the .deb file to install.
              • Ubuntu-Tweak will be available under Applications > System Tools.
              • To clean the kernels:
                • Select "Package Cleaner" on the left and ""Clean Kernel" from the right panel.
                • Press the "Unlock" button at the lower right, enter your password.
                • Select from the displayed list the kernel images and headers you wish to remove. The kernel in use is not listed.
                • Press the "Cleanup" button at the lower right to remove the selected kernel images and headers.


            • Too Many Operating Systems?
              • Other Operating Systems which have been removed from the computer will also be removed from the menu once "update-grub" is run as root.
              • Menu items are placed on the Grub2 menu by scripts. If you don't want other Operating Systems to be entered in the menu, disable /etc/grub.d/30_osprober
                • Run this command to stop the script from running: sudo chmod -x /etc/grub.d/30_os-prober
                • GRUB_DISABLE_OS_PROBER='true' in /etc/default/grub


            • Memtest86+
              • Code:
                sudo chmod -x /etc/grub.d/20_memtest86+


          • Run the update-grub command to allow the changes to be incorporated in grub.cfg



      • User-Created Entries.
        • To remove a user-created menu entry, remove the applicable file from the /etc/grub.d folder.
        • If a custom file contains multiple entries, individual items may be removed and others retained.
        • Once the file has been removed or edited, run "update-grub" to update grub.cfg.


    8. Grub 2 Splash Images & Theming
      There are two distinct areas of this section.

      Backgrounds & Fonts: In Grub 2, adding a background image and changing font colors is relatively easy and are detailed briefly below. I've included additional information in the Grub 2 Drop-In Backgrounds & Font Selection thread, which was written specifically for Grub 1.99 (Natty and later) but which can be applied in part in earlier versions.

      Here is a link to Herman's page on creating Grub 2 background images: http://members.iinet.net/~herman546/p20/GRUB2%20Splashimages.html]

      Themes: Although there are no easy-to-use GUI applications to construct great-looking themes, Grub 2 allows the user to create complex menus if the user wishes to construct them manually. Forum member towheedm has written an extremely comprehensive and well-documented guide to creating great-looking themes with Grub 2. His PDF document and sample files walk you through the process of buidling a custom theme. Take a look at his example in the thumbnail at the bottom of this post. Here is the download link for A Beginner's Guide to Theming GRUB2

      Adding a Background Image:
      • Manually copy grub splash images into the /usr/share/images/grub folder or install the default grub2 splash images via Synaptic or:
        Code:
        sudo apt-get install grub2-splashimages
      • The grub2's splash images are normally, but not always, controlled by /etc/grub.d/05_debian_theme. There are additional options in Grub 1.99 & later, and 2 variants in Grub 1.98 (see below).

        • Grub 1.99 (Natty)
          In addition to the methods mentioned in the next section, Grub 1.99 allows the user to simply place an image in the Grub folder. This image will be used as the Grub 2 splash image (background). Here are the details on how it works:
          Grub 2 Drop-In Backgrounds & Font Selection

        • Grub 1.98 late + Grub 1.99 (Maverick / Natty )
          Rather than edit the /etc/grub.d/05_header or /usr/share/desktop-base/grub_background.sh file, the user can now include the background image designation directly into /etc/default/grub. The path assumes the folder is located in the default system partition.
          GRUB_BACKGROUND=/path/filename
          Example: GRUB_BACKGROUND="/home/my_username/grub_images/my_grubimage.png"

        • Grub 1.98 (Lucid)
          For Grub 1.98, attempt to open the following two files for editing:
          Code:
          gksudo gedit /usr/share/desktop-base/grub_background.sh /etc/grub.d/05_debian_theme
          • If the file /usr/share/desktop-base/grub_background.sh is empty/blank, edit /etc/grub.d/05_debian_theme
          • If the file /usr/share/desktop-base/grub_background.sh exists, edit this file and not /etc/grub.d/05_debian_theme.


          Find the following line and edit the highlighted area, replacing it with the path and grub splash image you wish to use:
          WALLPAPER="/<path-to-image>/<your-image-name-here-including-extension>"
          Example: WALLPAPER="/home/my_username/grub_images/my_grubimage.png"

        • Grub 1.97~beta4
          Find the following line and edit the highlighted area, replacing it with the grub splash image you wish to use (and located in /usr/share/images/grub):
          for i in {/boot/grub,/usr/share/images/grub}/moreblue-orbit-grub.{png,tga} ; do
          Note: There is a period ( . ) following the filename.
          • At one point Grub 2 splash images were downloaded and stored in /usr/share/images/desktop.base If this is where your grub images are stored, change the address in the previous command accordingly ( ... /usr/share/images/desktop-base} ... ).

      • Save the file, then update grub2:
        Code:
        sudo update-grub


      A Note About Grub 2 Theming


    9. Changing Menu Resolutions
      If the user wishes to change the resolution of the GRUB 2 screen while using a splash image follow these steps:
      1. Set the desired resolution in /etc/default/grub
        • Change the value of GRUB_GFXMODE= (Example: GRUB_GFXMODE=800x600)
          • If unsure of what resolutions are available to GRUB 2 they can be displayed by typing vbeinfo in the GRUB 2 command line. The command line is accessed by typing "c" when the main GRUB 2 menu screen is displayed.


      2. Select an image of the same size and make the change in /etc/grub.d/05_debian_theme
        • The image name is located in the line beginning with "WALLPAPER=" (Grub 1.98) or " for i in {/boot" in Grub 1.97-beta.
        • If an image of the correct size is not used, the menu may not be positioned correctly.
        • Use the image editor of your choice to create/resize an image to the correct size.
        • The user may be able to view the image size via Properties in a file browser (check the Properties Image tab in Nautilus).
        • Images must be .tga, .png, or .jpg (8-bit) images, saved in RGB format (non-indexed).

      3. Run update-grub as root to add the new settings to /boot/grub/grub.cfg


    10. Basic Password Protection

      Note: To reduce the size of this entry, a separate post with information on establishing Grub 2 password protection is located on the Ubuntu forums at: Grub 2 Password Protection and in the links at the bottom of this post.

      Grub 2 currently supports unencrypted password protection. Encrypted password protection using PBKDF2, as well as password scripting, is currently under development.

      Some of the major points regarding Grub 2 password protection:
      • Grub 2 has the ability to set password protection on individual menuentries and/or for specific users. Examples: Password protect Windows Recovery; prevent user2 from opening the Recovery mode.
      • If password protection is enabled, the superuser username and password are required to gain access to the Grub 2 command line and menu editing modes.
      • The username and/or password do not have to be the same as the Ubuntu logon name/password.
      • This is basic password security. The name/password are unencrypted; anyone having physical access to the machine and more than an elementary knowledge of how Linux works will be able to access the configuration files and bypass this feature.
      • Grub 2 password protection is still being developed. Encryption is available in experimental versions only. If password protection is used, recheck your scripts for changes whenever a new Grub 2 update is released. In 1.97~beta4, passwords must be assigned to each desired menu item. In Lucid Lynx, expect Grub 1.97 to password protect the entire Grub 2 menu if a superuser is designated.


    11. How to Boot to the Recovery Mode w/o a Menu Option
      1. If you have Grub 2 set to boot without displaying the menu at all, hold the SHIFT key down until the menu displays. (In Grub it was the ESC key.)
      2. Press any key once the menu is displayed to 'freeze' it. Then arrow to the kernel you want to boot.
      3. Press "e"
      4. Scroll to the end of the "linux /boot/vmlinuz...." line. If displayed, remove "quiet" and/or "splash". Add the word "single" to the end of the line.
      5. Press CTRL-X to boot to the Recovery menu.


    12. Uninstalling GRUB 2
      The command line produces a cleaner uninstall and reinstallation. While adding and removing the packages can be accomplished with Synaptic, certain steps must be accomplished in a terminal.
      • Open a terminal: Applications, Accessories, Terminal.
      • Make backup copies of the main GRUB 2 folders & files
        • Code:
          sudo cp /etc/default/grub /etc/default/grub.old
          sudo cp -R /etc/grub.d /etc/grub.d.old
          sudo cp -R /boot/grub /boot/grub.old

      • Remove GRUB 2
        • Ensure you have an Internet connection and reliable power source. An interruption of either could leave your system in an unbootable condition.
        • Code:
          sudo apt-get purge grub-common grub-pc
        • The user will be warned the system will be unbootable without installing another bootloader.
        • Once the packages are removed, many files will still remain in '/boot/grub'

      • Install GRUB 2
        • Code:
          sudo apt-get install grub-common grub-pc
          • The user will be asked for any special commands to add to the default "linux" line. If you aren't sure, leave it blank, press the TAB key to highlight "OK" and press ENTER.
          • Select the appropriate drive on which to install Grub2 (sda, sdb, etc) by highlighting the entry and pressing the space bar. Normally a partition (sda1, etc) should not be selected.
        • Code:
          sudo update-grub
        • Reboot


    13. Reinstalling GRUB 2 from LiveCD
      If you cannot boot from GRUB 2 and need to reinstall it, here is the simple method. For more details or for advanced options, refer to the Ubuntu community documentation here: Grub2 - Reinstalling GRUB 2:
      • Boot the Ubuntu Live CD (Try without installing).
      • From the Desktop, open a terminal - Applications, Accessories, Terminal.
      • Determine your normal system partition - `sudo fdisk -l` (That is a lowercase L)
      • If you aren't sure, run `df -Th`. Look for the correct disk size and ext3 or ext4 format.
      • Mount your normal system partition:
        Code:
        sudo mount /dev/sdXY /mnt
        • If you aren't sure if you mounted the correct partition, once it's mounted run "nautilus /mnt" to inspect the partition. If it is the correct partition, you should see the normal Ubuntu folders such as /bin, /boot, /etc, /home, etc

        • Example: sudo mount /dev/sda1 /mnt
        • Note: The partition to mount is normally the partition on which Ubuntu was installed: sda1, sdb5, etc. If you have a separate /boot partition, use the device on which the /boot partition is located. Grub 2 works best when installed in the MBR of the drive to which BIOS boots. Also remember that you mount the partition (including the number) in this step, but you do not include the partition number when you run the "sudo grub-install" command later.
        • Note: GRUB 2 counts the first drive (X) as "0", but the first partition (Y) as "1"

      • Only if you have a separate boot partition:
        • Code:
          sudo mount /dev/sdXY /mnt/boot
          with sdXY being your /boot partition designation.

      • Reinstall GRUB 2:
        Code:
        sudo grub-install --root-directory=/mnt /dev/sdX
        Do NOT include the partition number.

        • Example: sudo grub-install --root-directory=/mnt /dev/sda
        • Note: Substitute the device on which Ubuntu was installed - sda, sdb, etc. Do not specify a partition number.

      • Unmount the partition *:
        Code:
        sudo umount /mnt
        • * Note: If you mounted a separate /boot partition, unmount it first:
          Code:
          sudo umount /mnt/boot
      • Reboot.


    14. Booting LiveCD and Other ISOs
      Grub 2 provides the capability to boot certain .iso images. These image files (ISO's) include the Ubuntu LiveCDs, SystemrescueCD and the Parted Magic CD.

      See the following thread in the Tutorials section for information and instructions on how to boot Ubuntu and other system ISOs:
      ISO Booting with Grub 2

    15. Booting from the Rescue Mode
      One of the improvements of Grub 2 is the ability to recover from a failed boot from the Grub 2 "grub rescue>" or "grub>" prompt. For a detailed discussion and instructions on booting from the Grub 2 prompt, please refer to this tutorial:
      HOWTO: Boot & Install Ubuntu from the Grub Rescue Prompt

      Additional information on the rescue mode is available in the "Command Line & Rescue Mode" section of the Ubuntu Grub 2 community doc.

    16. Restoring GRUB2 / XP / Vista / Win 7 Bootloaders
      talsemgeest has written an excellent guide on how to restore the bootloaders of various operating systems following the installation of another one. Make sure you reference the section for "9.10 and Beyond", which is for GRUB 2.

      Rather than duplicate his efforts in this post, here is the link to the original:
      http://ubuntuforums.org/showthread.php?t=1014708

      Restoring Windows MBR without a Windows CD
      If you want to boot directly to Windows but Grub has overwritten the MBR, the normal procdeure is to use the Windows CD to restore things. If you do not have access to the Windows CD, the following commands will rewrite the MBR, removing Grub and allowing the system to boot directly into Windows.

      Boot the Ubuntu LiveCD, open a terminal (Applications, Accessories, Terminal) and enter the following commands. Make sure you correctly identify the Windows device (normally sda):
      Code:
      sudo apt-get install lilo
      sudo lilo -M /dev/sda mbr
      Bonus Section: BSD Menuentry - If you need to have an entry to boot into BSD/Windows from the Grub2 menu, here is the menuentry to put into a custom file:
      menuentry "FreeBSD" {
      insmod ufs2
      set root=(hd1,1)
      chainloader +1
      }
    17. Grub Rescue Image
      A bootable Grub 2 rescue image is available for both floppies and CDs. To obtain the images, install "grub-rescue-pc". Once installed, three images are available in /usr/lib/grub-mkrescue. Use the I]grub-mkrescue [/I] command to create the rescue ISO. See the MAN page for more information. Note: A customized rescue ISO only uses the current systems Grub 2 /boot/grub files. No information from /etc/grub.d or /etc/default/grub is imported.

      The ISO only boots to the grub prompt. It uses the Grub 2 files found on the ISO; if the problem is with the system's Grub 2 files the rescue ISO should boot. However, the ISO contains no kernels and must be told where to find the correct kernel and initrd files on the system. The user must know the drive/partition on which the boot files are located and the non-Grub files must exist and be uncorrupted.

      If the user hasn't made a rescue floppy/ISO, other alternatives include the Ubuntu Installation/LiveCD or SuperGrub Disk.
      • grub-rescue-floppy.img - For floppy images.
        • To Install:
        • Insert a disk in the floppy drive.
        • Code:
          fdformat /dev/fd0
          mkfs -t msdos /dev/fd0
          dd if=/usr/lib/grub-rescue/grub-rescue-floppy.img of=/dev/fd0

      • grub-rescue-cdrom.iso - When burning the image to a CD, select the option to copy an image and not the files.
        • Generate the image using the following command:
          • Code:
            grub-mkrescue --output=<path/filename>

        • If an error message "/usr/bin/grub-mkrescue: 324: xorriso: not found", install the xorriso package and rerun the command.
        • Copy the ISO image to a CD using the CD burning app of your choice.



      Once the grub rescue floppy/CD boots to the grub prompt, run the following commands.

      The commands are slightly different than those used for booting by other means. The Grub 2 files on the floppy/CD are used, and only the kernel and initrd.img files need to be loaded.

      Command line tips:
      • Drives start counting at 0 (sda=0, sdb=1, etc). Partitions start counting at 1 (1=1, etc). Substitute the correct drive letter for X, correct number for Y, and substitute the correct numbers for (hd0,1).
      • You must type the entire path and kernel and initrd names if (hdX,Y)/vmlinuz and (hdX,Y)/initrd.img do not exist. You can check by running this command:
        • ls (hdX,Y)/


        If vmlinuz and initrd.img do not exist at (hdX,Y)/, you can simplify the typing using the TAB complete feature.
      • On the linux line, type "vml" and then TAB to help complete the kernel number. Ensure the complete kernel name is entered. Be sure to fill the kernel number completely, and don't forget the "root=" and "ro" sections of the linux line.
      • On the initrd line, type "ini" and TAB to fill in a large part of the name. Continue typing/TABBING to ensure the complete .img name is used.
      • Sections in bold should be changed to match the user's system.


      Code:
      set root=(hd0,1)
      linux (hdX,Y)/vmlinuz root=/dev/sdXY ro
      # or if (hdX,Y)/vmlinuz does not exist:
      linux (hdX,Y)/boot/vmlinuz-2.6.32.25-generic root=/dev/sdXY ro
      # then
      initrd (hdX,Y)/boot/initrd.img 
      # or if (hdX,Y)/initrd.img does not exist:
      initrd (hdX,Y)/boot/initrd.img-2.6.33-25-generic 
      boot
    18. Grub 2 Fallback
      There is a little-documented 'fallback' capability which allows Grub 2 to select an alternate menuentry should the default entry fail. Since Grub 2/Natty uses submenus which may alter the way to use fallback, this section covers Grub 1.98/Maverick & earlier.

      To designate a fallback menuentry, add the following to /etc/grub.d/40_custom. X is the menuentry number (start counting the grub.cfg menuentries at 0):
      set fallback=X
      Notes regarding the Grub 2 Fallback Option:
      • In Maverick, using the title rather than the menuentry number does not appear to work in /etc/grub.d/40_custom
      • The title can be used if set fallback="<title>" is placed in /boot/grub/grub.cfg, but is not recommended as it will be removed during updates.
      • Instructions for using the fallback option in Natty/Grub 1.99 will be added once Natty is officially released.


    19. Selected Problems & Bugs


      "out of disk" ,"device not found", "no such device" , "root device" Errors
      Causes are many, but can be caused by Grub2 not finding partitions/files it is looking for. Some possible areas to explore while troubleshooting:
      • Does your BIOS see the files? Older BIOS may not see past 8GB or 137GB of the partition. You may need to create a separate /boot partition or adjust the BIOS to use the 'large disk' mode or update the BIOS to allow it to use today's larger disks.
      • Some users may need to add "rootdelay=90" to the end of the "linux" line in /etc/default/grub. The might be necessary if the system takes a long time to recognize the drive.
      • The BIOS controller mode may need to be changed. Change the BIOS entry for the SATA Controller from from AHCI to Compatibility mode.


      Lubuntu Dual Booters - No Windows Menu
      Lubuntu apparently doesn't ship with the package os-prober so Windows will not be added to the Grub 2 menu. To add Windows, install os-prober, update grub and then check to see if Windows is now in the menu:
      Code:
      sudo apt-get install os-prober
      sudo update-grub
      grep menuentry /boot/grub/grub.cfg

      http://www.gnu.org/software/grub/manual/


      Grub Update results in "No Such Disk":
      A late July 2010 Grub 2 update is causing a "no such disk" error for some users of WUBI, resulting in an unbootable system. If the system doesn't display the original Windows menu, the most likely cause of the failure is that Grub 2 was installed in the MBR and/or on the Windows partition. To correct this, restore the Windows bootloader using this link:
      How to restore the Ubuntu/XP/Vista/7 bootloader

      Whether the failure is due to improper user selections or Grub 2's failure to recognize a Wubi install, it has been reported in the following bug and users can review it for status updates and recovery options when they become available:
      https://bugs.launchpad.net/wubi/+bug/610898


      "Fix Symbol 'grub-puts' Not Found" Error Message:
      http://www.webupd8.org/2010/05/fix-symbol-grubputs-not-found-when.html
      If you can get to a normal installation, run the grub-install command or use the "dpkg-reconfigure grub-pc" command to put Grub onto your current partition. If you have to use the Live CD, use chroot to run these commands (see chroot link in my signature line.


      Note: Most of this information has been incorporated, with a few graphics, into a page in the Ubuntu Help site. I will try to keep this post up-to-date and users are free to continue to post comments here. The help page is located here: https://help.ubuntu.com/community/Grub2


      meierfra has been busily building pages which detail how to solve many of the common problems users are experiencing with Grub 2. His SourceForge web page should be one of the first stops for those seeking answers to Grub 2 issues.


      Wubi (Windows Ubuntu) Users - wubildr
      Grub2 updates in the spring of 2010 triggered a bug in the ntfs module causing Wubi boot failures. The solution to this boot problem was posted by Agostino Russo and is found in this Lucid Lynx LaunchPad Bug Report #477169, Post 210. The module causing the errors has been fixed and replacing the "wubildr" file in Windows permanently solves this problem. meierfra has kindly provided clear instructions on how to fix this problem at http://sourceforge.net/apps/mediawiki/bootinfoscript/index.php?title=Boot_Problems:Wubi_9.10

      Lose Ubuntu/Windows After Installing the Other
      If you have lost the ability to boot into Windows or Ubuntu following the installation/reinstallation of the other OS it could be an overwritten MBR issue. If the OS was previously working, there is an excellent guide written by talsemgeest that may very well restore the lost OS. Here is the link:
      How to restore the Ubuntu/XP/Vista/7 bootloader (Updated for Ubuntu 9.10)


      No Menu On Initial Boot
      If you are already on the Ubuntu Desktop, run "sudo update-grub". This may detect additional operating systems, which may allow the Grub menu to be displayed on the next boot. Otherwise:
      Open /etc/default/grub:
      Code:
      gksu gedit /etc/default/grub
      Disable the "GRUB_HIDDEN_TIMEOUT=" line by placing a # symbol at the beginning of the line.
      Set "GRUB_TIMEOUT=" to a positive integer (number of seconds to display the menu before automatic selection) or "-1" to wait for the user to press ENTER (no timeout). The entry will look like this:
      #GRUB_HIDDEN_TIMEOUT=0
      GRUB_HIDDEN_TIMEOUT_QUIET=true
      GRUB_TIMEOUT="10"
      Save the file, update grub ("sudo update-grub") and reboot.


      HP Machines Fails to Load Grub after Using Windows - Bug bug/441941
      After installing Grub 2 on a HP machine, the system boots normally until the first time it's booted into Windows. On the next boot, the system hangs at "Grub loading".

      Workaround: HP protection tools are rewriting to the MBR when Windows is run. The protecttools app must be removed/disabled. Refer to post #10 in the Bug Report.


      "Grub loading. The symbol ' ' not found. Aborted." on Dell machines..
      On Dell computers with Dell DataSafe Local Backup (DDSLB) installed, the above message is displayed with a series of characters within the ' ' section. This is a reported bug,
      bug #482757. Thanks to merry_meercat's post which details how to fix the problem.

      "error: the symbol `grub_xputs` not found".
      Use the Live CD to chroot into your Ubuntu partition and purge/reinstall Grub2. See post #5 here:
      http://ubuntuforums.org/showpost.php?p=9836539&postcount=5.


      "error: unknown filesystem" on old motherboard & BIOS.
      If you are using an older motherboard/BIOS, make sure the BIOS and system can read your hard drive. There is a 137GB limit in old BIOS settings that prevents the system from recognizing data placed 'deeper' into the partition. Try creating a /boot partition smaller than 130GB and see if the system now recognizes it. You can also check to see if there is a BIOS update which may eliminate this problem.


      Grub "error: out of disk" or "failed to boot default entries".
      This error message is sometimes generated when Grub 2 cannot properly write to the file /boot/grub/grubenv. Refer to meierfra's Boot_Problems:Write page.


      "Grub loading. The symbol ' ' not found. Aborted." on Dell machines..
      On Dell computers with Dell DataSafe Local Backup (DDSLB) installed, the above message is displayed with a series of characters within the ' ' section. This is a reported bug,
      bug #482757. Thanks to merry_meercat's post which details how to fix the problem.

    20. Links
      My Threads
      Grub 2 (help.ubuntu.com)
      Grub 2: Title Tweaks
      Grub 2: 5 Common Tasks
      Grub 2: Introduction
      Grub 2: Purge & Reinstall
      Grub 2: ISO Booting with Grub 2
      Grub 2: Password Protection
      Grub 1.99 Changes
      Grub 1.99 Submenus
      Grub 2 Drop-In Backgrounds & Font Selection

      Apps
      Grub Customizer
      Boot Repair
      StartUp-Manager

      Other Links
      Wubi Megathread by Rubi1200
      Grub 2: A Guide for Users (from Kubuntu Forums)
      'Official' GNU Grub 2 Manual (1.99)
      GNU Grub 2 Manual/Wiki (in development)
      Grub 2 Wiki
      Herman's Grub 2 Site Comprehensive.
      Herman's Grub 2 Scripts Useful scripts for many Grub 2 tasks.
      How to restore the Ubuntu/XP/Vista/7 bootloader
      http://grub.gibibit.com/Grub 2 Theming (currently for Ubuntu G2 experimental)
      How to restore the Ubuntu/XP/Vista/7 bootloader
      http://sourceforge.net/apps/mediawik...itle=Main_Page meierfra's Grub 2 Solutions Page
      How-to Install 9.10 karmic on fakeraid by gilson585
      How to create a Grub 2 Floppy See post 283 of this thread. Thank you peter b
      Customizing the graphics in Grub See post 283 of this thread. Thank you peter b
      MultiBootUSB Script to install multiple OS's on thumb/USB drives. Thanks sundar_ima
      How to: Create a Customized GRUB2 Screen that is Maintenance Free Thanks Cavsfan
      The Definitive Guide To Theming GRUB 2 - 2nd Edition. PDF with Theme example files for your reading pleasure. The title says it all. Thanks towheedm


    A sample Grub 2 Theme as detailed by forum member towheedm:
    Attached Images Attached Images
    Last edited by drs305; July 3rd, 2012 at 11:55 PM.
    GRUB2

    Retired.

  2. #2
    Join Date
    Apr 2005
    Beans
    1,347

    Re: Grub 2 Basics

    I am running
    Code:
    sudo update-grub
    and have the following:
    Code:
    ~$ sudo update-grub
    Updating /boot/grub/grub.cfg ...
    Found linux image: /boot/vmlinuz-2.6.28-14-generic
    Found initrd image: /boot/initrd.img-2.6.28-14-generic
    Found linux image: /boot/vmlinuz-2.6.28-13-generic
    Found initrd image: /boot/initrd.img-2.6.28-13-generic
    Found linux image: /boot/vmlinuz-2.6.28-12-generic
    Found initrd image: /boot/initrd.img-2.6.28-12-generic
    Found linux image: /boot/vmlinuz-2.6.28-11-generic
    Found initrd image: /boot/initrd.img-2.6.28-11-generic
    Found memtest86+ image: /memtest86+.bin
    Found Ubuntu karmic (development branch) (9.10) on /dev/sda6
    done
    But it does not add the last Karmic entry in the menu:

    Code:
    #
    # DO NOT EDIT THIS FILE
    #
    # It is automatically generated by /usr/sbin/update-grub using templates
    # from /etc/grub.d and settings from /etc/default/grub
    #
    
    ### BEGIN /etc/grub.d/00_header ###
    set default=0
    set timeout=5
    set root=(hd0,9)
    search --fs-uuid --set 9018bfe2-9de3-4692-9883-fc2f875e6455
    if font /usr/share/grub/ascii.pff ; then
      set gfxmode=640x480
      insmod gfxterm
      insmod vbe
      terminal gfxterm
    fi
    ### END /etc/grub.d/00_header ###
    
    ### BEGIN /etc/grub.d/05_debian_theme ###
    set menu_color_normal=cyan/blue
    set menu_color_highlight=white/blue
    ### END /etc/grub.d/05_debian_theme ###
    
    ### BEGIN /etc/grub.d/10_hurd ###
    ### END /etc/grub.d/10_hurd ###
    
    ### BEGIN /etc/grub.d/10_linux ###
    set root=(hd0,8)
    search --fs-uuid --set c3eb67b1-7f8f-419b-a462-c79a6c76e5de
    menuentry "Ubuntu, linux 2.6.28-14-generic" {
    	linux	/vmlinuz-2.6.28-14-generic root=UUID=9018bfe2-9de3-4692-9883-fc2f875e6455 ro  quiet splash
    	initrd	/initrd.img-2.6.28-14-generic
    }
    menuentry "Ubuntu, linux 2.6.28-14-generic (single-user mode)" {
    	linux	/vmlinuz-2.6.28-14-generic root=UUID=9018bfe2-9de3-4692-9883-fc2f875e6455 ro single 
    	initrd	/initrd.img-2.6.28-14-generic
    }
    menuentry "Ubuntu, linux 2.6.28-13-generic" {
    	linux	/vmlinuz-2.6.28-13-generic root=UUID=9018bfe2-9de3-4692-9883-fc2f875e6455 ro  quiet splash
    	initrd	/initrd.img-2.6.28-13-generic
    }
    menuentry "Ubuntu, linux 2.6.28-13-generic (single-user mode)" {
    	linux	/vmlinuz-2.6.28-13-generic root=UUID=9018bfe2-9de3-4692-9883-fc2f875e6455 ro single 
    	initrd	/initrd.img-2.6.28-13-generic
    }
    menuentry "Ubuntu, linux 2.6.28-12-generic" {
    	linux	/vmlinuz-2.6.28-12-generic root=UUID=9018bfe2-9de3-4692-9883-fc2f875e6455 ro  quiet splash
    	initrd	/initrd.img-2.6.28-12-generic
    }
    menuentry "Ubuntu, linux 2.6.28-12-generic (single-user mode)" {
    	linux	/vmlinuz-2.6.28-12-generic root=UUID=9018bfe2-9de3-4692-9883-fc2f875e6455 ro single 
    	initrd	/initrd.img-2.6.28-12-generic
    }
    menuentry "Ubuntu, linux 2.6.28-11-generic" {
    	linux	/vmlinuz-2.6.28-11-generic root=UUID=9018bfe2-9de3-4692-9883-fc2f875e6455 ro  quiet splash
    	initrd	/initrd.img-2.6.28-11-generic
    }
    menuentry "Ubuntu, linux 2.6.28-11-generic (single-user mode)" {
    	linux	/vmlinuz-2.6.28-11-generic root=UUID=9018bfe2-9de3-4692-9883-fc2f875e6455 ro single 
    	initrd	/initrd.img-2.6.28-11-generic
    }
    ### END /etc/grub.d/10_linux ###
    
    ### BEGIN /etc/grub.d/20_memtest86+ ###
    menuentry "Memory test (memtest86+)" {
    	linux	/memtest86+.bin
    }
    menuentry "Memory test (memtest86+, serial console 115200)" {
    	linux	/memtest86+.bin console=ttyS0,115200n8
    }
    ### END /etc/grub.d/20_memtest86+ ###
    
    ### BEGIN /etc/grub.d/30_os-prober ###
    ### END /etc/grub.d/30_os-prober ###
    
    ### BEGIN /etc/grub.d/40_custom ###
    # This file is an example on how to add custom entries
    ### END /etc/grub.d/40_custom ###
    ASUS K53S Ubuntu 14.04 64-bit
    ASUS U36jc, i5-480M, 2.66GHz, 4Gb, nVidia Optimus Ubuntu 14.04 64-bit
    HP DV6-2113sa, AMD Turion™ II M620, 4Gb, ATI Radeon™ HD 4530 Ubuntu 14.04 64-bit
    ASUS 1015PX Netbook Lubuntu 14.04

  3. #3
    Join Date
    Jan 2007
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    Ubuntu Development Release

    Re: Grub 2 Basics

    I don't know why grub2 isn't picking it up. I have had a few instances of grub2 not picking up all the kernels scattered over my drives but I don't remember grub2 actually ignoring ones that it located.

    Here are a couple of things I do when troubleshooting:

    a. Change one of the titles so I know the grub.cfg I see when it boots is the one I am looking at in the editor (i.e. if there are multiple grub.cfg files on your system). You will have to chmod +w to actually edit grub.cfg

    b. Search your system for multiple instances of the file.

    c. Place the kernel you want to show up in /etc/grub.d/40_custom so at least it shows up when you update grub. At best you will have two instances - the detected and the custom entries; at worst you will have at least the one from the 40_custom file. Don't forget to make the file executable.

    d. Reinstall grub2 with grub-install.
    Last edited by drs305; July 18th, 2009 at 12:38 PM. Reason: 40_custom file problem
    GRUB2

    Retired.

  4. #4
    Join Date
    Apr 2005
    Beans
    1,347

    Re: Grub 2 Basics

    It seems I have to unmount the Karmic partition before running 'grub-setup'. It has listed Karmic now. But I still cannot log in. I have now a message something like:
    Code:
    booting from kernel on /dev/sda6
    you need to load kernel first
    The entries in grub.cfg:
    Code:
    set root=(hd0,8) 
    search --fs-uuid --set c3eb67b1-7f8f-419b-a462-c79a6c76e5de
    menuentry "Ubuntu, linux 2.6.28-14-generic" {
    	linux	/vmlinuz-2.6.28-14-generic root=UUID=9018bfe2-9de3-4692-9883-fc2f875e6455 ro  quiet splash
    	initrd	/initrd.img-2.6.28-14-generic
    
    menuentry "Ubuntu karmic (development branch), kernel 2.6.31-2-generic (on /dev/sda6)" {
    	set root=(hd0,7)
    	linux /boot/vmlinuz-2.6.31-2-generic root=UUID=6ad1f928-50b9-4aea-9495-95df46d08d58 ro quiet splash
    	initrd /boot/initrd.img-2.6.31-2-generic
    The first entry is for Jaunty, which is my primary OS, the second is for Karmic.

    This is my fstab:
    Code:
    # / was on /dev/sda9 during installation
    UUID=9018bfe2-9de3-4692-9883-fc2f875e6455 /               ext3    relatime,errors=remount-ro 0       1
    
    # /boot was on /dev/sda8 during installation
    UUID=c3eb67b1-7f8f-419b-a462-c79a6c76e5de /boot           ext2    relatime        0       2
    
    # /home was on /dev/sda5 during installation
    UUID=4802e809-ecaa-4932-bd01-4a816c0bbd4f /home           ext3    relatime        0       2
    
    # /media/test_boot was on /dev/sda7 during installation
    UUID=0c98fbe4-ed7c-4134-994a-07d49074e137 /media/test_boot ext2    relatime        0       2
    
    # /test was on /dev/sda6 during installation
    UUID=6ad1f928-50b9-4aea-9495-95df46d08d58 /test           ext3    relatime        0       2
    I am a bit lost with all this partition numbers
    ASUS K53S Ubuntu 14.04 64-bit
    ASUS U36jc, i5-480M, 2.66GHz, 4Gb, nVidia Optimus Ubuntu 14.04 64-bit
    HP DV6-2113sa, AMD Turion™ II M620, 4Gb, ATI Radeon™ HD 4530 Ubuntu 14.04 64-bit
    ASUS 1015PX Netbook Lubuntu 14.04

  5. #5
    Join Date
    Jan 2007
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    Ubuntu Development Release

    Re: Grub 2 Basics

    Quote Originally Posted by foxy123 View Post
    I still cannot log in. I have now a message something like:
    Code:
    booting from kernel on /dev/sda6
    you need to load kernel first
    The entries in grub.cfg:
    Code:
    menuentry "Ubuntu karmic (development branch), kernel 2.6.31-2-generic (on /dev/sda6)" {
    	set root=(hd0,7)
    	linux /boot/vmlinuz-2.6.31-2-generic root=UUID=6ad1f928-50b9-4aea-9495-95df46d08d58 ro quiet splash
    	initrd /boot/initrd.img-2.6.31-2-generic
    This is my fstab:
    Code:
    # /test was on /dev/sda6 during installation
    UUID=6ad1f928-50b9-4aea-9495-95df46d08d58 /test           ext3    relatime        0       2
    I am a bit lost with all this partition numbers
    Edit: foxy123 has a separate boot partition for his Karmic install as well, so his sda7 entry was correct. The following was written before I found out the separate test-boot partition was linked to the Karmic installation.

    I believe the problem is with your partition numbers. First, a disclaimer. I'm relying on the comments in fstab being accurate. Since they aren't updated, they really can't be relied upon unless confirmed via "mount", "sudo blkid", or some other command. So I'm relying on sda6 being the correct partition number. I'm also making the assumption that the Karmic install is on sda6 and not sda7, since it is the sda6 UUID in the boot menu.

    Grub 2 counts partitions a bit differently. sdXY, with X being the device (a,b,c) and Y being the partition number (1,2,3). The device starts counting at 0 - sda is device 0. The partitions (and this is a change) start counting at 1, so partition 1 is counted as 1. So sdb3 is device 1, partition 3.

    In your setup, sda6 should be listed as (0,6). Try this as your Karmic entry and see if it works correctly. If it doesn't, confirm the device and UUID designations by running "sudo blkid -c /dev/null".

    menuentry "Ubuntu karmic (development branch), kernel 2.6.31-2-generic (on /dev/sda6)" {
    set root=(hd0,6)
    linux /boot/vmlinuz-2.6.31-2-generic root=UUID=6ad1f928-50b9-4aea-9495-95df46d08d58 ro quiet splash
    initrd /boot/initrd.img-2.6.31-2-generic

    Last edited by drs305; July 19th, 2009 at 04:49 PM.
    GRUB2

    Retired.

  6. #6
    Join Date
    Jul 2009
    Beans
    2

    Re: Grub 2 Basics

    What about LILO?

    You may have heard about another Linux bootloader called LILO (stands for LInux LOader). While a sensible option for many Linux users, I believe that GRUB is a better choice, for several reasons:

    • LILO supports only up to 16 different boot selections; GRUB supports an unlimited number of boot entries.
    • LILO cannot boot from network; GRUB can.
    • LILO must be written again every time you change the configuration file; GRUB does not.
    • LILO does not have an interactive command interface.

    All in all, it seems that GRUB is the winner. So let's see what this baby can do.

  7. #7
    Join Date
    Apr 2005
    Beans
    1,347

    Re: Grub 2 Basics

    well, no luck. Same error. Also after I have it I cannot boot into Jaunty (same error) and have to reboot.

    I have checked with sudo blkid -c /dev/null:

    Code:
    /dev/sda2: UUID="4d5250be-75cf-4ce4-9295-ae5e2cabd441" TYPE="swap" 
    /dev/sda5: UUID="4802e809-ecaa-4932-bd01-4a816c0bbd4f" TYPE="ext3" - my /home partition
    /dev/sda6: UUID="6ad1f928-50b9-4aea-9495-95df46d08d58" TYPE="ext3" - Karmic / partition
    /dev/sda7: UUID="0c98fbe4-ed7c-4134-994a-07d49074e137" TYPE="ext2" - Karmic /boot partition
    /dev/sda8: UUID="c3eb67b1-7f8f-419b-a462-c79a6c76e5de" TYPE="ext2" - Jaunty /boot partition
    /dev/sda9: UUID="9018bfe2-9de3-4692-9883-fc2f875e6455" TYPE="ext3" - Jaunty / partition
    In the Jaunty setup the menu points out to a /boot partition (sda8 c3eb67b1-7f8f-419b-a462-c79a6c76e5de). So I have to use something like:

    Code:
    menuentry "Ubuntu karmic (development branch), kernel 2.6.31-2-generic (on /dev/sda6)" {
    	set root=(hd0,7)
    	linux /boot/vmlinuz-2.6.31-2-generic root=UUID=0c98fbe4-ed7c-4134-994a-07d49074e137 ro quiet splash
    	initrd /boot/initrd.img-2.6.31-2-generic
    But it does not either
    ASUS K53S Ubuntu 14.04 64-bit
    ASUS U36jc, i5-480M, 2.66GHz, 4Gb, nVidia Optimus Ubuntu 14.04 64-bit
    HP DV6-2113sa, AMD Turion™ II M620, 4Gb, ATI Radeon™ HD 4530 Ubuntu 14.04 64-bit
    ASUS 1015PX Netbook Lubuntu 14.04

  8. #8
    Join Date
    Oct 2004
    Location
    Switzerland
    Beans
    60

    Re: Grub 2 Basics

    Thank you for the background information.

    I am having a small issue I cannot figure out. It is not world stopping but annoying.

    I have also posted this on the kubuntu forum as I am running Kubuntu but since we are all a family:
    http://kubuntuforums.net/forums/inde...opic=3105336.0

    To be short here, my issue is the following:
    I have a ubuntu 9.04 and a kubuntu karmic partition with grub2 on a separate /boot.

    The grub2 boot menu shows 2 ubuntu's.
    One pointing to the swap partition the other going to the correct partition.

    The details are on the link above.

    Any help would be greatly appreciated

    As some of mentioned that they cannot see the atch. on the kubuntu site I will add them here as well. sorry.
    Attached Files Attached Files
    Last edited by Fintan; July 26th, 2009 at 03:25 PM.

  9. #9
    Join Date
    Feb 2005
    Location
    Paris, France
    Beans
    19
    Distro
    Ubuntu 9.04 Jaunty Jackalope

    Post Re: Grub 2 Basics

    Hi guys,

    Pretty good guide, thanx.
    I have a problem that many guys have aparently,
    but I think it's not exactly about the same issue.
    I get...
    Quote Originally Posted by my computer
    Invalid or unsupported executable format
    ... when I hit my Windows Grub launcher.

    Here is my fdisk
    Code:
    Disque /dev/sda: 1000.2 Go, 1000204886016 octets
    255 têtes, 63 secteurs/piste, 121601 cylindres, total 1953525168 secteurs
    Unités = secteurs de 1 * 512 = 512 octets
    Identifiant de disque : 0x00063093
    
    Périphérique Amorce  Début        Fin      Blocs     Id  Système
    /dev/sda1   *          63  1941455249   970727593+  83  Linux
    /dev/sda2      1941455250  1953520064     6032407+   5  Etendue
    /dev/sda5      1941455313  1953520064     6032376   82  Linux swap / Solaris
    
    Disque /dev/sdb: 320.0 Go, 320072933376 octets
    255 têtes, 63 secteurs/piste, 38913 cylindres, total 625142448 secteurs
    Unités = secteurs de 1 * 512 = 512 octets
    Identifiant de disque : 0x375e8732
    
    Périphérique Amorce  Début        Fin      Blocs     Id  Système
    /dev/sdb1   *          63    40965749    20482843+   6  FAT16
    /dev/sdb2        40965750   625137344   292085797+   f  W95 Etendue (LBA)
    /dev/sdb5        40965813   625137344   292085766    7  HPFS/NTFS
    
    Disque /dev/sdc: 203.9 Go, 203928109056 octets
    255 têtes, 63 secteurs/piste, 24792 cylindres, total 398297088 secteurs
    Unités = secteurs de 1 * 512 = 512 octets
    Identifiant de disque : 0x16c175da
    
    Périphérique Amorce  Début        Fin      Blocs     Id  Système
    /dev/sdc1   *          63   398283479   199141708+   7  HPFS/NTFS
    Here is my Windows Grub boot file section:

    Code:
    title           Microsoft Windows XP Professional
    rootnoverify    (hd2,0)
    savedefault
    makeactive
    map             (hd0) (hd2)
    map             (hd2) (hd0)
    chainloader     +1
    My Windows system is actually located in sdc1.

    Do somebody have a clue ?

  10. #10
    Join Date
    Jan 2007
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    Ubuntu Development Release

    Re: Grub 2 Basics

    Quote Originally Posted by glide View Post
    My Windows system is actually located in sdc1.
    Do somebody have a clue ?
    Glide,

    I don't have a lot of expertise with setting up dual boots with Windows - if it was something obvious and I had a solution I'd post it here.

    It appears yours is a Grub legacy question. Since this thread was written about Grub 2, I suggest you create a new thread for your issue. It will get a bit confusing if we mix the two on this thread.

    Thanks.
    GRUB2

    Retired.

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