grubby(8) - command line tool used to configure bootloader menu entries...

  • GRUBBY(8)                   System Manager's Manual                  GRUBBY(8)
           grubby  -  command  line tool used to configure bootloader menu entries
           across multiple architectures
           grubby [OPTIONS]
       General Information
           grubby is a command line tool for updating and  displaying  information
           about  the  configuration files for various architecture specific boot‐
           loaders.  It is primarily  designed  to  be  used  from  scripts  which
           install new kernels and need to find information about the current boot
       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  boot‐
           loader are fully supported.
           Support for yaboot has been deprecated as all ppc architecture hardware
           since the Power8 uses grub2 or petitboot which both use the grub2  con‐
           figuration 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  architec‐
           ture  for  which  grubby  has been built.  Each architecture has a pre‐
           ferred bootloader, and each bootloader has its own configuration  file.
           If no bootloader is selected on the command line, grubby will use these
           default settings to search for an existing configuration.  If no  boot‐
           loader  configuration  file is found, grubby will use the default value
           for that architecture.  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                  │
       Special Arguments
           There are a number of ways to  specify  the  kernel  used  for  --info,
           --remove-kernel, and --update-kernel. Specifying DEFAULT or ALL selects
           the default entry and all of the entries,  respectively.   If  a  comma
           separated  list  of numbers is given, the boot entries indexed by those
           numbers are selected. Finally, the title of a boot entry may be  speci‐
           fied  by using TITLE=title as the argument; all entries with that title
           are used.
       Basic Options
                  Add a new boot entry for the kernel located  at  kernel-path.  A
                  title for the boot entry must be set using --title. Most invoca‐
                  tions should also include --initrd with memtest86 as  a  notable
                  The  --update-kernel  option may not be used in the same invoca‐
                  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 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.
                  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. Multiple, space sepa‐
                  rated  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).
                  The arguments specified by kernel-args are removed from the ker‐
                  nels  specified  by --update-kernel. The root argument gets spe‐
                  cial handling for configuration files that support separate root
                  filesystem configuration.
                  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.
                  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.
                  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 architec‐
                  The first entry which boots the specified  kernel  is  made  the
                  default  boot entry. This may not be invoked with --set-default-
                  Makes the given entry number the default boot  entry.  This  may
                  not  be  invoked with --set-default.  The given value represents
                  the index in the post-modification boot entry list.
                  Make the new kernel entry being added the default entry.
                  Set the position at which to add a new entry created with --add-
                  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.
                  Display the full path to the current default kernel and exit.
                  Display the numeric index of the current default boot entry  and
                  Display the title of the current default boot entry and exit.
                  Display information on all boot entries which match kernel-path.
                  If kernel-path is DEFAULT, then information on the default  ker‐
                  nel is displayed. If kernel-path is ALL, then information on all
                  boot entries are displayed.
                  Attempt to probe for installed bootloaders.  If this  option  is
                  specified,  grubby  tries  to  determine if grub or lilo is cur‐
                  rently 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 cre‐
                  This option is only available on x86 BIOS platforms.
           -v, --version
                  Display the version of grubby being run and  then  exit  immedi‐
       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 configura‐
           tion file format may be specified on the command  line  if  the  system
           uses a supported alternative bootloader.
                  Use  an  elilo  style configuration file. This is the default on
                  ia64 platforms. This format is deprecated.
                  Use an extlinux style configuration file. This format is  depre‐
           --grub Use  a grub style configuration file. This is the default on the
                  i386 architecture.
                  Use a grub2 style configuration file. This  is  the  default  on
                  x86_64  architecture  as well as the ppc64 and ppc64le architec‐
                  tures 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, deprecated, and unsup‐
                  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 architectures.
       Override Options
                  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  primarily  for
                  The grub boot loader expects file paths listed in its configura‐
                  tion 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  filesys‐
                  tems  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).
                  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.
                  Use path for device tree path  in  place  of  the  path  of  any
                  devicetree directive found in the template stanza.
                  Use  the  specified file path to load the devicetree definition.
                  This is for platforms where a  flat  file  is  used  instead  of
                  firmware to instruct the kernel how to communicate with devices.
       Multiboot Options
           The Multiboot Specification provides a generic interface for boot load‐
           ers and operating systems.  It is supported by the GRUB bootloader.
                  Add a new boot entry for the multiboot kernel located at  multi‐
                  boot-path.   Note  that  this  is  generally  accompanied with a
                  --add-kernel option.
                  Removes all boot entries which match multiboot-path.
                  When a new multiboot kernel is added, this specifies the command
                  line  arguments which should be passed to that kernel by default
                  When --update-kernel is used, this specifies  new  arguments  to
                  add  to  the  argument list. Multiple, space separated arguments
                  may be used.  If  an  argument  already  exists  the  new  value
                  replaces the old values.
                  The  arguments  specified by multiboot-args are removed from the
                  kernels specified by --update-kernel.
           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.
           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  white‐
           space  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"  --ini‐
                  trd="new_initrd" --copy-default
           Add a new kernel entry with custom arguments
                  grubby  --add-kernel=new_kernel   --title="entry_title"   --ini‐
                  trd="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
           Update the arguments for all entries of a specific  kernel.  New  argu‐
           ments get added while existing arguments get updated values.
                  grubby --update-kernel=current_kernel --args="kernel_args"
           Remove the arguments for a single entry of a specific kernel.
                  grubby --info=current_kernel
                  grubby --remove-args=menu_index --args="kernel_args"
           grub(8), lilo(8), yaboot(8), zipl(8), dracut(8), mkinitrd(8)
           Erik Troan
           Jeremy Katz
           Peter Jones
           Robert Marshall
                                    Tue Jan 18 2005                      GRUBBY(8)

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