This manual is for GNU GRUB (version @value{VERSION},
@value{UPDATED}).
-Copyright @copyright{} 1999,2000,2001,2002,2004,2006,2008,2009 Free Software Foundation, Inc.
+Copyright @copyright{} 1999,2000,2001,2002,2004,2006,2008,2009,2010 Free Software Foundation, Inc.
@quotation
Permission is granted to copy, distribute and/or modify this document
@direntry
* GRUB: (grub). The GRand Unified Bootloader
* grub-install: (grub)Invoking grub-install. Install GRUB on your drive
+* grub-mkconfig: (grub)Invoking grub-mkconfig. Generate GRUB configuration
@end direntry
@setchapternewpage odd
* Troubleshooting:: Error messages produced by GRUB
* Invoking the grub shell:: How to use the grub shell
* Invoking grub-install:: How to use the GRUB installer
+* Invoking grub-mkconfig:: Generate a GRUB configuration file
* Obtaining and Building GRUB:: How to obtain and build GRUB
* Reporting bugs:: Where you should send a bug report
* Future:: Some future plans on GRUB
kernel. @xref{uppermem}, for more information.
+@node Configuration
+@chapter Writing your own configuration file
+
+GRUB is configured using @file{grub.cfg}, usually located under
+@file{/boot/grub}. This file is quite flexible, but most users will not
+need to write the whole thing by hand.
+
+@menu
+* Simple configuration:: Recommended for most users
+* Shell-like scripting:: For power users and developers
+@end menu
+
+
+@node Simple configuration
+@section Simple configuration handling
+
+The program @command{grub-mkconfig} (@pxref{Invoking grub-mkconfig})
+generates @file{grub.cfg} files suitable for most cases. It is suitable for
+use when upgrading a distribution, and will discover available kernels and
+attempt to generate menu entries for them.
+
+The file @file{/etc/default/grub} controls the operation of
+@command{grub-mkconfig}. It is sourced by a shell script, and so must be
+valid POSIX shell input; normally, it will just be a sequence of
+@samp{KEY=value} lines, but if the value contains spaces or other special
+characters then it must be quoted. For example:
+
+@example
+GRUB_TERMINAL_INPUT="console serial"
+@end example
+
+Valid keys in @file{/etc/default/grub} are as follows:
+
+@table @samp
+@item GRUB_DEFAULT
+The default menu entry. This may be a number, in which case it identifies
+the Nth entry in the generated menu counted from zero, or the full name of a
+menu entry, or the special string @samp{saved}. Using the full name may be
+useful if you want to set a menu entry as the default even though there may
+be a variable number of entries before it.
+
+If you set this to @samp{saved}, then the default menu entry will be that
+saved by @samp{GRUB_SAVEDEFAULT}, @command{grub-set-default}, or
+@command{grub-reboot}.
+
+The default is @samp{0}.
+
+@item GRUB_SAVEDEFAULT
+If this option is set to @samp{true}, then, when an entry is selected, save
+it as a new default entry for use by future runs of GRUB. This is only
+useful if @samp{GRUB_DEFAULT=saved}; it is a separate option because
+@samp{GRUB_DEFAULT=saved} is useful without this option, in conjunction with
+@command{grub-set-default} or @command{grub-reboot}. Unset by default.
+
+@item GRUB_TIMEOUT
+Boot the default entry this many seconds after the menu is displayed, unless
+a key is pressed. The default is @samp{5}. Set to @samp{0} to boot
+immediately without displaying the menu, or to @samp{-1} to wait
+indefinitely.
+
+@item GRUB_HIDDEN_TIMEOUT
+Wait this many seconds for a key to be pressed before displaying the menu.
+If no key is pressed during that time, boot immediately. Unset by default.
+
+@item GRUB_HIDDEN_TIMEOUT_QUIET
+In conjunction with @samp{GRUB_HIDDEN_TIMEOUT}, set this to @samp{true} to
+suppress the verbose countdown while waiting for a key to be pressed before
+displaying the menu. Unset by default.
+
+@item GRUB_DEFAULT_BUTTON
+@itemx GRUB_TIMEOUT_BUTTON
+@itemx GRUB_HIDDEN_TIMEOUT_BUTTON
+@itemx GRUB_BUTTON_CMOS_ADDRESS
+Variants of the corresponding variables without the @samp{_BUTTON} suffix,
+used to support vendor-specific power buttons. @xref{Vendor power-on keys}.
+
+@item GRUB_DISTRIBUTOR
+Set by distributors of GRUB to their identifying name. This is used to
+generate more informative menu entry titles.
+
+@item GRUB_TERMINAL_INPUT
+Select the terminal input device. You may select multiple devices here,
+separated by spaces.
+
+Valid terminal input names depend on the platform, but may include
+@samp{console} (PC BIOS and EFI consoles), @samp{serial} (serial terminal),
+@samp{ofconsole} (Open Firmware console), @samp{at_keyboard} (PC AT
+keyboard, mainly useful with Coreboot), or @samp{usb_keyboard} (USB keyboard
+using the HID Boot Protocol, for cases where the firmware does not handle
+this).
+
+The default is to use the platform's native terminal input.
+
+@item GRUB_TERMINAL_OUTPUT
+Select the terminal output device. You may select multiple devices here,
+separated by spaces.
+
+Valid terminal output names depend on the platform, but may include
+@samp{console} (PC BIOS and EFI consoles), @samp{serial} (serial terminal),
+@samp{gfxterm} (graphics-mode output), @samp{ofconsole} (Open Firmware
+console), or @samp{vga_text} (VGA text output, mainly useful with Coreboot).
+
+The default is to use the platform's native terminal input.
+
+@item GRUB_TERMINAL
+If this option is set, it overrides both @samp{GRUB_TERMINAL_INPUT} and
+@samp{GRUB_TERMINAL_OUTPUT} to the same value.
+
+@item GRUB_SERIAL_COMMAND
+A command to configure the serial port when using the serial console.
+@xref{serial}. Defaults to @samp{serial}.
+
+@item GRUB_CMDLINE_LINUX
+Command-line arguments to add to menu entries for the Linux kernel.
+
+@item GRUB_CMDLINE_LINUX_DEFAULT
+Unless @samp{GRUB_DISABLE_LINUX_RECOVERY} is set, two menu entries will be
+generated for each Linux kernel: one default entry and one entry for
+recovery mode. This option lists command-line arguments to add only to the
+default menu entry, after those listed in @samp{GRUB_CMDLINE_LINUX}.
+
+@item GRUB_CMDLINE_NETBSD
+@itemx GRUB_CMDLINE_NETBSD_DEFAULT
+As @samp{GRUB_CMDLINE_LINUX} and @samp{GRUB_CMDLINE_LINUX_DEFAULT}, but for
+NetBSD.
+
+@item GRUB_DISABLE_LINUX_UUID
+Normally, @command{grub-mkconfig} will generate menu entries that use
+universally-unique identifiers (UUIDs) to identify the root filesystem to
+the Linux kernel, using a @samp{root=UUID=...} kernel parameter. This is
+usually more reliable, but in some cases it may not be appropriate. To
+disable the use of UUIDs, set this option to @samp{true}.
+
+@item GRUB_DISABLE_LINUX_RECOVERY
+Disable the generation of recovery mode menu entries for Linux.
+
+@item GRUB_DISABLE_NETBSD_RECOVERY
+Disable the generation of recovery mode menu entries for NetBSD.
+
+@item GRUB_GFXMODE
+Set the resolution used on the @samp{gfxterm} graphical terminal. Note that
+you can only use modes which your graphics card supports via VESA BIOS
+Extensions (VBE), so for example native LCD panel resolutions may not be
+available. The default is @samp{640x480}.
+
+@item GRUB_BACKGROUND
+Set a background image for use with the @samp{gfxterm} graphical terminal.
+The value of this option must be a file readable by GRUB at boot time, and
+it must end with @file{.png}, @file{.tga}, @file{.jpg}, or @file{.jpeg}.
+The image will be scaled if necessary to fit the screen.
+
+@item GRUB_THEME
+Set a theme for use with the @samp{gfxterm} graphical terminal.
+@xref{Themes}.
+
+@item GRUB_GFXPAYLOAD_LINUX
+Set to @samp{text} to force the Linux kernel to boot in normal text mode,
+@samp{keep} to preserve the graphics mode set using @samp{GRUB_GFXMODE},
+@samp{@var{width}x@var{height}}[@samp{x@var{depth}}] to set a particular
+graphics mode, or a sequence of these separated by commas or semicolons to
+try several modes in sequence.
+
+Depending on your kernel, your distribution, your graphics card, and the
+phase of the moon, note that using this option may cause GNU/Linux to suffer
+from various display problems, particularly during the early part of the
+boot sequence. If you have problems, simply unset this option and GRUB will
+tell Linux to boot in normal text mode.
+
+@item GRUB_DISABLE_OS_PROBER
+Normally, @command{grub-mkconfig} will try to use the external
+@command{os-prober} program, if installed, to discover other operating
+systems installed on the same system and generate appropriate menu entries
+for them. Set this option to @samp{true} to disable this.
+
+@item GRUB_INIT_TUNE
+Play a tune on the speaker when GRUB starts. This is particularly useful
+for users unable to see the screen. The value of this option is passed
+directly to @ref{play}.
+@end table
+
+For more detailed customisation of @command{grub-mkconfig}'s output, you may
+edit the scripts in @file{/etc/grub.d} directly.
+@file{/etc/grub.d/40_custom} is particularly useful for adding entire custom
+menu entries; simply type the menu entries you want to add at the end of
+that file, making sure to leave at least the first two lines intact.
+
+
+@node Shell-like scripting
+@section Writing full configuration files directly
+
+
@node Serial terminal
@chapter Using GRUB via a serial line
@end table
+@node Invoking grub-mkconfig
+@chapter Invoking grub-mkconfig
+
+The program @command{grub-mkconfig} generates a configuration file for GRUB
+(@pxref{Simple configuration}).
+
+@example
+grub-mkconfig -o /boot/grub/grub.cfg
+@end example
+
+@command{grub-mkconfig} accepts the following options:
+
+@table @option
+@item --help
+Print a summary of the command-line options and exit.
+
+@item --version
+Print the version number of GRUB and exit.
+
+@item -o @var{file}
+@itemx --output=@var{file}
+Send the generated configuration file to @var{file}. The default is to send
+it to standard output.
+@end table
+
+
@node Obtaining and Building GRUB
@appendix How to obtain and build GRUB
projects / thirdparty / grub.git / commitdiff
