1GRUBBY(8) System Manager's Manual GRUBBY(8)
2
6 grubby - command line tool used to configure bootloader menu entries
7 across multiple architectures
8
11 grubby [OPTIONS]
12
15 General Information
16 grubby is a command line tool for updating and displaying information
17 about the configuration files for various architecture specific boot‐
18 loaders. It is primarily designed to be used from scripts which
19 install new kernels and need to find information about the current boot
20 environment.
21 Architecture Support
24 The grubby executable has full support for the grub2 bootloader on
25 x86_64 systems using legacy BIOS or modern UEFI firmware and ppc64 and
26 ppc64le hardware using OPAL or SLOF as firmware.
27 Legacy s390 and the current s390x architectures and their zipl boot‐
29 loader are fully supported.
30 Support for yaboot has been deprecated as all ppc architecture hardware
32 since the Power8 uses grub2 or petitboot which both use the grub2 con‐
33 figuration file format.
34 Legacy bootloaders LILO, SILO, and ELILO are deprecated and no longer
36 receiving active support in favor of previously mentioned bootloaders.
37 Default Behavior
40 The default bootloader target is primarily determined by the architec‐
41 ture for which grubby has been built. Each architecture has a pre‐
42 ferred bootloader, and each bootloader has its own configuration file.
43 If no bootloader is selected on the command line, grubby will use these
44 default settings to search for an existing configuration. If no boot‐
45 loader configuration file is found, grubby will use the default value
46 for that architecture. These defaults are listed in the table below.
47 ┌────────────────┬────────────┬─────────────────────────────────┐
50 │ Arch │ Bootloader │ Configuration File │
51 ├────────────────┼────────────┼─────────────────────────────────┤
52 │ x86_64 [BIOS] │ grub2 │ /boot/grub2/grub.cfg │
53 ├────────────────┼────────────┼─────────────────────────────────┤
54 │ x86_64 [UEFI] │ grub2 │ /boot/efi/EFI/redhat/grub.cfg │
55 ├────────────────┼────────────┼─────────────────────────────────┤
56 │ i386 │ grub2 │ /boot/grub2/grub.cfg │
57 ├────────────────┼────────────┼─────────────────────────────────┤
58 │ ia64 │ elilo │ /boot/efi/EFI/redhat/elilo.conf │
59 ├────────────────┼────────────┼─────────────────────────────────┤
60 │ ppc [>=Power8] │ grub2 │ /boot/grub2/grub.cfg │
61 ├────────────────┼────────────┼─────────────────────────────────┤
62 │ ppc [<=Power7] │ yaboot │ /etc/yaboot.conf │
63 ├────────────────┼────────────┼─────────────────────────────────┤
64 │ s390 │ zipl │ /etc/zipl.conf │
65 ├────────────────┼────────────┼─────────────────────────────────┤
66 │ s390x │ zipl │ /etc/zipl.conf │
67 └────────────────┴────────────┴─────────────────────────────────┘
68 Special Arguments
71 There are a number of ways to specify the kernel used for --info,
72 --remove-kernel, and --update-kernel. Specifying DEFAULT or ALL selects
73 the default entry and all of the entries, respectively. If a comma
74 separated list of numbers is given, the boot entries indexed by those
75 numbers are selected. Finally, the title of a boot entry may be speci‐
76 fied by using TITLE=title as the argument; all entries with that title
77 are used.
78
81 Basic Options
82 --add-kernel=kernel-path
83 Add a new boot entry for the kernel located at kernel-path. A
84 title for the boot entry must be set using --title. Most invoca‐
85 tions should also include --initrd with memtest86 as a notable
86 exception.
87 The --update-kernel option may not be used in the same invoca‐
89 tion.
90 --remove-kernel=kernel-path
93 Remove all boot entries which match kernel-path. This may be
94 used along with --add-kernel, in which case the new entry being
95 added will not be removed.
96 --update-kernel=kernel-path
99 Update the entries for kernels matching kernel-path. Currently
100 the only item that can be updated is the kernel argument list,
101 which is modified via the --args and --remove-args options.
102 --args=kernel-args
105 When a new kernel is added, this specifies the command line
106 arguments which should be passed to the kernel by default (note
107 they are merged with the arguments from the template if --copy-
108 default is used). When --update-kernel is used, this specifies
109 new arguments to add to the argument list. Multiple, space sepa‐
110 rated arguments may be used. If an argument already exists the
111 new value replaces the old values. The root= kernel argument
112 gets special handling if the configuration file has special han‐
113 dling for specifying the root filesystem (like lilo.conf does).
114 --remove-args=kernel-args
117 The arguments specified by kernel-args are removed from the ker‐
118 nels specified by --update-kernel. The root argument gets spe‐
119 cial handling for configuration files that support separate root
120 filesystem configuration.
121 --copy-default
124 grubby will copy as much information (such as kernel arguments
125 and root device) as possible from the current default kernel.
126 The kernel path and initrd path will never be copied.
127 --title=entry-title
130 When a new kernel entry is added entry-title is used as the
131 title (lilo label) for the entry. If entry-title is longer then
132 maximum length allowed by the bootloader (15 for lilo, unlimited
133 for grub and elilo) the title is shortened to a (unique) entry.
134 --initrd=initrd-path
137 Use initrd-path as the path to an initial ram disk for a new
138 kernel being added.
139 --efi Use appropriate bootloader commands for EFI on this architec‐
142 ture.
143 --set-default=kernel-path
146 The first entry which boots the specified kernel is made the
147 default boot entry. This may not be invoked with --set-default-
148 index.
149 --set-default-index=entry-index
152 Makes the given entry number the default boot entry. This may
153 not be invoked with --set-default. The given value represents
154 the index in the post-modification boot entry list.
155 --make-default
158 Make the new kernel entry being added the default entry.
159 --set-index=entry-index
162 Set the position at which to add a new entry created with --add-
163 kernel.
164 --debug
167 Display extra debugging information for failures.
168 -i, --extra-initrd=initrd-path
171 Use initrd-path as the path for an auxiliary initrd image.
172 Display Options
175 Passing the display option to grubby will cause it to print out the
176 requested information about the current bootloader configuration and
177 then immediately exit. These options should not be used in any script
178 intended to update the bootloader configuration.
179 --default-kernel
182 Display the full path to the current default kernel and exit.
183 --default-index
186 Display the numeric index of the current default boot entry and
187 exit.
188 --default-title
191 Display the title of the current default boot entry and exit.
192 --info=kernel-path
195 Display information on all boot entries which match kernel-path.
196 I
197 --bootloader-probe
200 Attempt to probe for installed bootloaders. If this option is
201 specified, grubby tries to determine if grub or lilo is cur‐
202 rently installed. When one of those bootloaders is found the
203 name of that bootloader is displayed on stdout. Both could be
204 installed (on different devices), and grubby will print out the
205 names of both bootloaders, one per line. The probe for grub
206 requires a commented out boot directive grub.conf identical to
207 the standard directive in the lilo configuration file. If this
208 is not present grubby will assume grub is not installed (note
209 that anaconda places this directive in grub.conf files it cre‐
210 ates).
211 This option is only available on x86 BIOS platforms.
213 -v, --version
216 Display the version of grubby being run and then exit immedi‐
217 ately.
218 Output Format Options
221 Sane default options for the current platform are compiled into grubby
222 on a per platform basis. These defaults determine the format and layout
223 of the generated bootloader configuration file. A different configura‐
224 tion file format may be specified on the command line if the system
225 uses a supported alternative bootloader.
226 --elilo
229 Use an elilo style configuration file. This is the default on
230 ia64 platforms. This format is deprecated.
231 --extlinux
234 Use an extlinux style configuration file. This format is depre‐
235 cated.
236 --grub Use a grub style configuration file. This is the default on the
239 i386 architecture.
240 --grub2
243 Use a grub2 style configuration file. This is the default on
244 x86_64 architecture as well as the ppc64 and ppc64le architec‐
245 tures running on Power8 or later hardware.
246 --lilo Use a lilo style configuration file.
249 --silo Use a silo style configuration file. This is the default on
252 SPARC systems. This format is legacy, deprecated, and unsup‐
253 ported.
254 --yaboot
257 Use a yaboot style configuration file. This is the default for
258 the ppc architecture on on Power7 and earlier hardware.
259 --zipl Use a zipl style configuration file. This is the default on the
262 legacy s390 and current s390x architectures.
263 Override Options
266 --bad-image-okay
267 When grubby is looking for a entry to use for something (such as
268 a template or a default boot entry) it uses sanity checks, such
269 as ensuring that the kernel exists in the filesystem, to make
270 sure entries that obviously won't work aren't selected. This
271 option overrides that behavior, and is designed primarily for
272 testing.
273 --boot-filesystem=bootfs
276 The grub boot loader expects file paths listed in its configura‐
277 tion path to be relative to the top of the filesystem they are
278 on, rather then relative to the current root filesystem. By
279 default grubby searches the list of currently mounted filesys‐
280 tems to determine this. If this option is given grubby acts as
281 if the specified filesystem was the filesystem containing the
282 kernel (this option is designed primarily for testing).
283 --env=path
286 Path for the file where grub environment data is stored.
287 -c, --config-file=path
290 Use path as the configuration file rather then the default.
291 -o, --output-file=file_path
294 The destination path for the updated configuration file. Use "-"
295 to send it to stdout.
296 Multiboot Options
299 The Multiboot Specification provides a generic interface for boot load‐
300 ers and operating systems. It is supported by the GRUB bootloader.
301 --add-multiboot=multiboot-path
304 Add a new boot entry for the multiboot kernel located at multi‐
305 boot-path. Note that this is generally accompanied with a
306 --add-kernel option.
307 --remove-multiboot=multiboot-path
310 Removes all boot entries which match multiboot-path.
311 --mbargs=multiboot-args
314 When a new multiboot kernel is added, this specifies the command
315 line arguments which should be passed to that kernel by default
316 When --update-kernel is used, this specifies new arguments to
317 add to the argument list. Multiple, space separated arguments
318 may be used. If an argument already exists the new value
319 replaces the old values.
320 --remove-mbargs=multiboot-args
323 The arguments specified by multiboot-args are removed from the
324 kernels specified by --update-kernel.
325
328 The command line syntax is more than a little baroque. This probably
329 won't be fixed as grubby is only intended to be called from shell
330 scripts which can get it right.
331
334 The following examples assume the following:
335 ┌────────────────┬─────────────────────────────────────────────┐
338 │ cfg_file │ Full path to bootloader config file │
339 ├────────────────┼─────────────────────────────────────────────┤
340 │ new_kernel │ Full path to kernel image to be installed │
341 ├────────────────┼─────────────────────────────────────────────┤
342 │ old_kernel │ Full path to old kernel image to be removed │
343 ├────────────────┼─────────────────────────────────────────────┤
344 │ current_kernel │ Full path to a currently installed kernel │
345 ├────────────────┼─────────────────────────────────────────────┤
346 │ entry_title │ Title that appears on bootloader menu │
347 ├────────────────┼─────────────────────────────────────────────┤
348 │ new_initrd │ Full path to initrd for a new kernel │
349 ├────────────────┼─────────────────────────────────────────────┤
350 │ kernel_args │ Set of arguments for the kernel │
351 ├────────────────┼─────────────────────────────────────────────┤
352 │ menu_index │ Index number of a menu entry │
353 └────────────────┴─────────────────────────────────────────────┘
354 The examples below quote strings that may have spaces or other white‐
355 space in them. It is also perfectly valid to backslash escape these
356 strings if that is more convenient.
357 Add a new kernel entry and copy all options from the current default
360 kernel. This is the behavior that most users will want.
361 grubby --add-kernel=new_kernel --title="entry_title" --ini‐
363 trd="new_initrd" --copy-default
364 Add a new kernel entry with custom arguments
366 grubby --add-kernel=new_kernel --title="entry_title" --ini‐
368 trd="new_initrd" --args=kernel_args
369 Remove all menu entries for a specified kernel.
371 grubby --remove-kernel=old_kernel
373 Target a single menu entry to remove without targetting other entries
375 with the same kernel.
376 grubby --info=old_kernel
378 grubby --remove-kernel=menu_index
380 Update the arguments for all entries of a specific kernel. New argu‐
382 ments get added while existing arguments get updated values.
383 grubby --update-kernel=current_kernel --args="kernel_args"
385 Remove the arguments for a single entry of a specific kernel.
387 grubby --info=current_kernel
389 grubby --remove-args=menu_index --args="kernel_args"
391
394 grub(8), lilo(8), yaboot(8), zipl(8), dracut(8), mkinitrd(8)
395
398 Erik Troan
399 Jeremy Katz
400 Peter Jones
401 Robert Marshall
402 Tue Jan 18 2005 GRUBBY(8)