GRUBBY(8) System Manager's Manual GRUBBY(8)
NAME
grubby - command line tool used to configure bootloader menu entries across multiple architectures
SYNOPSIS
grubby [OPTIONS]
DESCRIPTION
General Information
grubby is a command line tool for updating and displaying information about the configuration files for vari‐
ous architecture specific bootloaders. It is primarily designed to be used from scripts which install new
kernels and need to find information about the current boot environment.
Architecture Support
The grubby executable has full support for the grub2 bootloader on x86_64 systems using legacy BIOS or modern
UEFI firmware and ppc64 and ppc64le hardware using OPAL or SLOF as firmware.
Legacy s390 and the current s390x architectures and their zipl bootloader are fully supported.
Support for yaboot has been deprecated as all ppc architecture hardware since the Power8 uses grub2 or petit‐
boot which both use the grub2 configuration file format.
Legacy bootloaders LILO, SILO, and ELILO are deprecated and no longer receiving active support in favor of
previously mentioned bootloaders.
Default Behavior
The default bootloader target is primarily determined by the architecture for which grubby has been built.
Each architecture has a preferred bootloader, and each bootloader has its own configuration file. If no boot‐
loader is selected on the command line, grubby will use these default settings to search for an existing con‐
figuration. If no bootloader configuration file is found, grubby will use the default value for that archi‐
tecture. These defaults are listed in the table below.
┌────────────────┬────────────┬─────────────────────────────────┐
│ Arch │ Bootloader │ Configuration File │
├────────────────┼────────────┼─────────────────────────────────┤
│ x86_64 [BIOS] │ grub2 │ /boot/grub2/grub.cfg │
├────────────────┼────────────┼─────────────────────────────────┤
│ x86_64 [UEFI] │ grub2 │ /boot/efi/EFI/redhat/grub.cfg │
├────────────────┼────────────┼─────────────────────────────────┤
│ i386 │ grub2 │ /boot/grub2/grub.cfg │
├────────────────┼────────────┼─────────────────────────────────┤
│ ia64 │ elilo │ /boot/efi/EFI/redhat/elilo.conf │
├────────────────┼────────────┼─────────────────────────────────┤
│ ppc [>=Power8] │ grub2 │ /boot/grub2/grub.cfg │
├────────────────┼────────────┼─────────────────────────────────┤
│ ppc [<=Power7] │ yaboot │ /etc/yaboot.conf │
├────────────────┼────────────┼─────────────────────────────────┤
│ s390 │ zipl │ /etc/zipl.conf │
├────────────────┼────────────┼─────────────────────────────────┤
│ s390x │ zipl │ /etc/zipl.conf │
└────────────────┴────────────┴─────────────────────────────────┘
using --title. Most invocations should also include --initrd with memtest86 as a notable exception.
The --update-kernel option may not be used in the same invocation.
--remove-kernel=kernel-path
Remove all boot entries which match kernel-path. This may be used along with --add-kernel, in which
case the new entry being added will not be removed.
--update-kernel=kernel-path
Update the entries for kernels matching kernel-path. Currently the only item that can be updated is the
kernel argument list, which is modified via the --args and --remove-args options.
--args=kernel-args
When a new kernel is added, this specifies the command line arguments which should be passed to the
kernel by default (note they are merged with the arguments from the template if --copy-default is
used). When --update-kernel is used, this specifies new arguments to add to the argument list. Multi‐
ple, space separated arguments may be used. If an argument already exists the new value replaces the
old values. The root= kernel argument gets special handling if the configuration file has special han‐
dling for specifying the root filesystem (like lilo.conf does).
--remove-args=kernel-args
The arguments specified by kernel-args are removed from the kernels specified by --update-kernel. The
root argument gets special handling for configuration files that support separate root filesystem con‐
figuration.
--copy-default
grubby will copy as much information (such as kernel arguments and root device) as possible from the
current default kernel. The kernel path and initrd path will never be copied.
--title=entry-title
When a new kernel entry is added entry-title is used as the title (lilo label) for the entry. If entry-
title is longer then maximum length allowed by the bootloader (15 for lilo, unlimited for grub and
elilo) the title is shortened to a (unique) entry.
--initrd=initrd-path
Use initrd-path as the path to an initial ram disk for a new kernel being added.
--efi Use appropriate bootloader commands for EFI on this architecture.
--set-default=kernel-path
The first entry which boots the specified kernel is made the default boot entry. This may not be
invoked with --set-default-index.
--set-default-index=entry-index
--debug
Display extra debugging information for failures.
-i, --extra-initrd=initrd-path
Use initrd-path as the path for an auxiliary initrd image.
Display Options
Passing the display option to grubby will cause it to print out the requested information about the current
bootloader configuration and then immediately exit. These options should not be used in any script intended
to update the bootloader configuration.
--default-kernel
Display the full path to the current default kernel and exit.
--default-index
Display the numeric index of the current default boot entry and exit.
--default-title
Display the title of the current default boot entry and exit.
--info=kernel-path
Display information on all boot entries which match kernel-path. I
--bootloader-probe
Attempt to probe for installed bootloaders. If this option is specified, grubby tries to determine if
grub or lilo is currently installed. When one of those bootloaders is found the name of that bootloader
is displayed on stdout. Both could be installed (on different devices), and grubby will print out the
names of both bootloaders, one per line. The probe for grub requires a commented out boot directive
grub.conf identical to the standard directive in the lilo configuration file. If this is not present
grubby will assume grub is not installed (note that anaconda places this directive in grub.conf files
it creates).
This option is only available on x86 BIOS platforms.
-v, --version
Display the version of grubby being run and then exit immediately.
Output Format Options
Sane default options for the current platform are compiled into grubby on a per platform basis. These defaults
determine the format and layout of the generated bootloader configuration file. A different configuration file
format may be specified on the command line if the system uses a supported alternative bootloader.
--elilo
Use an elilo style configuration file. This is the default on ia64 platforms. This format is depre‐
and ppc64le architectures running on Power8 or later hardware.
--lilo Use a lilo style configuration file.
--silo Use a silo style configuration file. This is the default on SPARC systems. This format is legacy, dep‐
recated, and unsupported.
--yaboot
Use a yaboot style configuration file. This is the default for the ppc architecture on on Power7 and
earlier hardware.
--zipl Use a zipl style configuration file. This is the default on the legacy s390 and current s390x architec‐
tures.
Override Options
--bad-image-okay
When grubby is looking for a entry to use for something (such as a template or a default boot entry) it
uses sanity checks, such as ensuring that the kernel exists in the filesystem, to make sure entries
that obviously won't work aren't selected. This option overrides that behavior, and is designed primar‐
ily for testing.
--boot-filesystem=bootfs
The grub boot loader expects file paths listed in its configuration path to be relative to the top of
the filesystem they are on, rather then relative to the current root filesystem. By default grubby
searches the list of currently mounted filesystems to determine this. If this option is given grubby
acts as if the specified filesystem was the filesystem containing the kernel (this option is designed
primarily for testing).
--env=path
Path for the file where grub environment data is stored.
-c, --config-file=path
Use path as the configuration file rather then the default.
-o, --output-file=file_path
The destination path for the updated configuration file. Use "-" to send it to stdout.
Multiboot Options
The Multiboot Specification provides a generic interface for boot loaders and operating systems. It is sup‐
ported by the GRUB bootloader.
--add-multiboot=multiboot-path
Add a new boot entry for the multiboot kernel located at multiboot-path. Note that this is generally
--remove-mbargs=multiboot-args
The arguments specified by multiboot-args are removed from the kernels specified by --update-kernel.
BUGS
The command line syntax is more than a little baroque. This probably won't be fixed as grubby is only intended
to be called from shell scripts which can get it right.
EXAMPLE
The following examples assume the following:
┌────────────────┬─────────────────────────────────────────────┐
│ cfg_file │ Full path to bootloader config file │
├────────────────┼─────────────────────────────────────────────┤
│ new_kernel │ Full path to kernel image to be installed │
├────────────────┼─────────────────────────────────────────────┤
│ old_kernel │ Full path to old kernel image to be removed │
├────────────────┼─────────────────────────────────────────────┤
│ current_kernel │ Full path to a currently installed kernel │
├────────────────┼─────────────────────────────────────────────┤
│ entry_title │ Title that appears on bootloader menu │
├────────────────┼─────────────────────────────────────────────┤
│ new_initrd │ Full path to initrd for a new kernel │
├────────────────┼─────────────────────────────────────────────┤
│ kernel_args │ Set of arguments for the kernel │
├────────────────┼─────────────────────────────────────────────┤
│ menu_index │ Index number of a menu entry │
└────────────────┴─────────────────────────────────────────────┘
The examples below quote strings that may have spaces or other whitespace in them. It is also perfectly valid
to backslash escape these strings if that is more convenient.
Add a new kernel entry and copy all options from the current default kernel. This is the behavior that most
users will want.
grubby --add-kernel=new_kernel --title="entry_title" --initrd="new_initrd" --copy-default
Add a new kernel entry with custom arguments
grubby --add-kernel=new_kernel --title="entry_title" --initrd="new_initrd" --args=kernel_args
Remove all menu entries for a specified kernel.
grubby --remove-kernel=old_kernel
Target a single menu entry to remove without targetting other entries with the same kernel.
grubby --info=old_kernel
grubby --remove-kernel=menu_index
SEE ALSO
grub(8), lilo(8), yaboot(8), zipl(8), dracut(8), mkinitrd(8)
AUTHORS
Erik Troan
Jeremy Katz
Peter Jones
Robert Marshall
Tue Jan 18 2005 GRUBBY(8)
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