1SFDISK(8) System Administration SFDISK(8)
2
6 sfdisk - display or manipulate a disk partition table
7
9 sfdisk [options] device [-N partition-number]
10 sfdisk [options] command
12
14 sfdisk is a script-oriented tool for partitioning any block device. It
15 runs in interactive mode if executed on terminal (stdin refers to a
16 terminal).
17 Since version 2.26 sfdisk supports MBR (DOS), GPT, SUN and SGI disk
19 labels, but no longer provides any functionality for CHS (Cylinder-
20 Head-Sector) addressing. CHS has never been important for Linux, and
21 this addressing concept does not make any sense for new devices.
22 sfdisk (since version 2.26) aligns the start and end of partitions to
24 block-device I/O limits when relative sizes are specified, when the
25 default values are used or when multiplicative suffixes (e.g., MiB) are
26 used for sizes. It is possible that partition size will be optimized
27 (reduced or enlarged) due to alignment if the start offset is specified
28 exactly in sectors and partition size relative or by multiplicative
29 suffixes.
30 The recommended way is not to specify start offsets at all and specify
32 partition size in MiB, GiB (or so). In this case sfdisk align all par‐
33 titions to block-device I/O limits (or when I/O limits are too small
34 then to megabyte boundary to keep disk layout portable). If this
35 default behaviour is unwanted (usually for very small partitions) then
36 specify offsets and sizes in sectors. In this case sfdisk entirely
37 follows specified numbers without any optimization.
38 sfdisk does not create the standard system partitions for SGI and SUN
40 disk labels like fdisk(8) does. It is necessary to explicitly create
41 all partitions including whole-disk system partitions.
42 sfdisk uses BLKRRPART (reread partition table) ioctl to make sure that
44 the device is not used by system or another tools (see also --no-
45 reread). It's possible that this feature or another sfdisk activity
46 races with udevd. The recommended way how to avoid possible collisions
47 is to use exclusive flock for the whole-disk device to serialize device
48 access. The exclusive lock will cause udevd to skip the event handling
49 on the device. For example:
50 flock /dev/sdc sfdisk /dev/sdc
52 Note, this semantic is not currently supported by udevd for MD and DM
54 devices.
55
58 The commands are mutually exclusive.
59 [-N partition-number] device
61 The default sfdisk command is to read the specification for the
62 desired partitioning of device from standard input, and then
63 create a partition table according to the specification. See
64 below for the description of the input format. If standard
65 input is a terminal, then sfdisk starts an interactive session.
66 If the option -N is specified, then the changes are applied to
68 the partition addressed by partition-number. The unspecified
69 fields of the partition are not modified.
70 Note that it's possible to address an unused partition with -N.
72 For example, an MBR always contains 4 partitions, but the number
73 of used partitions may be smaller. In this case sfdisk follows
74 the default values from the partition table and does not use
75 built-in defaults for the unused partition given with -N. See
76 also --append.
77 -A, --activate device [partition-number...]
79 Switch on the bootable flag for the specified partitions and
80 switch off the bootable flag on all unspecified partitions. The
81 special placeholder '-' may be used instead of the partition
82 numbers to switch off the bootable flag on all partitions.
83 The activation command is supported for MBR and PMBR only. If
85 GPT label is detected than sfdisk prints warning and automati‐
86 cally enter PMBR.
87 If no partition-number is specified, then list the partitions
89 with an enabled flag.
90 --delete device [partition-number...]
92 Delete all or the specified partitions.
93 -d, --dump device
95 Dump the partitions of a device in a format that is usable as
96 input to sfdisk. See the section BACKING UP THE PARTITION TA‐
97 BLE.
98 -g, --show-geometry [device...]
100 List the geometry of all or the specified devices. For backward
101 compatibility the deprecated option --show-pt-geometry have the
102 same meaning as this one.
103 -J, --json device
105 Dump the partitions of a device in JSON format. Note that
106 sfdisk is not able to use JSON as input format.
107 -l, --list [device...]
109 List the partitions of all or the specified devices. This com‐
110 mand can be used together with --verify.
111 -F, --list-free [device...]
113 List the free unpartitioned areas on all or the specified
114 devices.
115 --part-attrs device partition-number [attributes]
117 Change the GPT partition attribute bits. If attributes is not
118 specified, then print the current partition settings. The
119 attributes argument is a comma- or space-delimited list of bits.
120 The currently supported attribute bits are: RequiredPartition,
121 NoBlockIOProtocol, LegacyBIOSBootable and GUID-specific bits in
122 the range from 48 to 63. For example, the string "RequiredPar‐
123 tition,50,51" sets three bits.
124 --part-label device partition-number [label]
126 Change the GPT partition name (label). If label is not speci‐
127 fied, then print the current partition label.
128 --part-type device partition-number [type]
130 Change the partition type. If type is not specified, then print
131 the current partition type. The type argument is hexadecimal
132 for MBR, or a GUID for GPT. For backward compatibility the
133 options -c and --id have the same meaning as this one.
134 --part-uuid device partition-number [uuid]
136 Change the GPT partition UUID. If uuid is not specified, then
137 print the current partition UUID.
138 -r, --reorder device
140 Renumber the partitions, ordering them by their start offset.
141 -s, --show-size [device...]
143 List the sizes of all or the specified devices in units of 1024
144 byte size. This command is DEPRECATED in favour of blockdev(8).
145 -T, --list-types
147 Print all supported types for the current disk label or the
148 label specified by --label.
149 -V, --verify [device...]
151 Test whether the partition table and partitions seem correct.
152
155 -a, --append
156 Don't create a new partition table, but only append the speci‐
157 fied partitions.
158 -b, --backup
160 Back up the current partition table sectors before starting the
161 partitioning. The default backup file name is
162 ~/sfdisk-<device>-<offset>.bak; to use another name see option
163 -O, --backup-file.
164 --color[=when]
166 Colorize the output. The optional argument when can be auto,
167 never or always. If the when argument is omitted, it defaults
168 to auto. The colors can be disabled; for the current built-in
169 default see the --help output. See also the COLORS section.
170 -f, --force
172 Disable all consistency checking.
173 --Linux
175 Deprecated and ignored option. Partitioning that is compatible
176 with Linux (and other modern operating systems) is the default.
177 -n, --no-act
179 Do everything except writing to the device.
180 --no-reread
182 Do not check through the re-read-partition-table ioctl whether
183 the device is in use.
184 --no-tell-kernel
186 Don't tell the kernel about partition changes. This option is
187 recommended together with --no-reread to modify a partition on
188 used disk. The modified partition should not be used (e.g.,
189 mounted).
190 -O, --backup-file path
192 Override the default backup file name. Note that the device
193 name and offset are always appended to the file name.
194 --move-data[=path]
196 Move data after partition relocation, for example when moving
197 the beginning of a partition to another place on the disk. The
198 size of the partition has to remain the same, the new and old
199 location may overlap. This option requires option -N in order
200 to be processed on one specific partition only.
201 The optional path specifies log file name. The log file contains
203 information about all read/write operations on the partition
204 data. The word "@default" as a path forces sfdisk to use
205 ~/sfdisk-<devname>.move for the log. The log is optional since
206 v2.35.
207 Note that this operation is risky and not atomic. Don't forget
209 to backup your data!
210 See also --move-use-fsync.
212 In the example below, the first command creates a 100MiB free
214 area before the first partition and moves the data it contains
215 (e.g., a filesystem), the next command creates a new partition
216 from the free space (at offset 2048), and the last command
217 reorders partitions to match disk order (the original sdc1 will
218 become sdc2).
219 echo '+100M,' | sfdisk --move-data /dev/sdc -N 1
221 echo '2048,' | sfdisk /dev/sdc --append
222 sfdisk /dev/sdc --reorder
223 --move-use-fsync
227 Use fsync system call after each write when move dara to a new
228 location by --move-data.
229 -o, --output list
231 Specify which output columns to print. Use --help to get a list
232 of all supported columns.
233 The default list of columns may be extended if list is specified
235 in the format +list (e.g., -o +UUID).
236 -q, --quiet
238 Suppress extra info messages.
239 -u, --unit S
241 Deprecated option. Only the sector unit is supported. This
242 option is not supported when using the --show-size command.
243 -X, --label type
245 Specify the disk label type (e.g., dos, gpt, ...). If this
246 option is not given, then sfdisk defaults to the existing label,
247 but if there is no label on the device yet, then the type
248 defaults to dos. The default or the current label may be over‐
249 written by the "label: <name>" script header line. The option
250 --label does not force sfdisk to create empty disk label (see
251 the EMPTY DISK LABEL section below).
252 -Y, --label-nested type
254 Force editing of a nested disk label. The primary disk label
255 has to exist already. This option allows to edit for example a
256 hybrid/protective MBR on devices with GPT.
257 -w, --wipe when
260 Wipe filesystem, RAID and partition-table signatures from the
261 device, in order to avoid possible collisions. The argument
262 when can be auto, never or always. When this option is not
263 given, the default is auto, in which case signatures are wiped
264 only when in interactive mode; except the old partition-table
265 signatures which are always wiped before create a new partition-
266 table if the argument when is not never. In all cases detected
267 signatures are reported by warning messages before a new parti‐
268 tion table is created. See also wipefs(8) command.
269 -W, --wipe-partitions when
272 Wipe filesystem, RAID and partition-table signatures from a
273 newly created partitions, in order to avoid possible collisions.
274 The argument when can be auto, never or always. When this
275 option is not given, the default is auto, in which case signa‐
276 tures are wiped only when in interactive mode and after confir‐
277 mation by user. In all cases detected signatures are reported
278 by warning messages after a new partition is created. See also
279 wipefs(8) command.
280 -v, --version
283 Display version information and exit.
284 -h, --help
286 Display help text and exit.
287
290 sfdisk supports two input formats and generic header lines.
291 Header lines
293 The optional header lines specify generic information that apply
294 to the partition table. The header-line format is:
295 <name>: <value>
297 The currently recognized headers are:
299 unit Specify the partitioning unit. The only supported
301 unit is sectors.
302 label Specify the partition table type. For example dos
304 or gpt.
305 label-id
307 Specify the partition table identifier. It should
308 be a hexadecimal number (with a 0x prefix) for
309 MBR and a UUID for GPT.
310 first-lba
312 Specify the first usable sector for GPT parti‐
313 tions.
314 last-lba
316 Specify the last usable sector for GPT partitions.
317 table-length
319 Specify the maximal number of GPT partitions.
320 grain Specify minimal size in bytes used to calculate
322 partitions alignment. The default is 1MiB and
323 it's strongly recommended to use the default. Do
324 not modify this variable if you're not sure.
325 sector-size
327 Specify sector size. This header is informative
328 only and it is not used when sfdisk creates a new
329 partition table, in this case the real device spe‐
330 cific value is always used and sector size from
331 the dump is ignored.
332 Note that it is only possible to use header lines before the
334 first partition is specified in the input.
335 Unnamed-fields format
337 start size type bootable
339 where each line fills one partition descriptor.
341 Fields are separated by whitespace, comma or semicolon possibly
343 followed by whitespace; initial and trailing whitespace is
344 ignored. Numbers can be octal, decimal or hexadecimal; decimal
345 is the default. When a field is absent, empty or specified as
346 '-' a default value is used. But when the -N option (change a
347 single partition) is given, the default for each field is its
348 previous value.
349 The default value of start is the first non-assigned sector
351 aligned according to device I/O limits. The default start off‐
352 set for the first partition is 1 MiB. The offset may be fol‐
353 lowed by the multiplicative suffixes (KiB, MiB, GiB, TiB, PiB,
354 EiB, ZiB and YiB) then the number is interpreted as offset in
355 bytes.
356 The default value of size indicates "as much as possible"; i.e.,
358 until the next partition or end-of-device. A numerical argument
359 is by default interpreted as a number of sectors, however if the
360 size is followed by one of the multiplicative suffixes (KiB,
361 MiB, GiB, TiB, PiB, EiB, ZiB and YiB) then the number is inter‐
362 preted as the size of the partition in bytes and it is then
363 aligned according to the device I/O limits. A '+' can be used
364 instead of a number to enlarge the partition as much as possi‐
365 ble. Note '+' is equivalent to the default behaviour for a new
366 partition; existing partitions will be resized as required.
367 The partition type is given in hex for MBR (DOS), without the 0x
369 prefix, a GUID string for GPT, or a shortcut:
370 L Linux; means 83 for MBR and
372 0FC63DAF-8483-4772-8E79-3D69D8477DE4 for GPT.
373 S swap area; means 82 for MBR and 0657FD6D-
375 A4AB-43C4-84E5-0933C84B4F4F for GPT
376 E extended partition; means 5 for MBR
378 H home partition; means
380 933AC7E1-2EB4-4F13-B844-0E14E2AEF915 for GPT
381 X linux extended partition; means 85 for MBR.
383 U EFI System partition, means EF for MBR and
385 C12A7328-F81F-11D2-BA4B-00A0C93EC93B for GPT
386 R Linux RAID; means FD for MBR and
388 A19D880F-05FC-4D3B-A006-743F0F84911E for GPT
389 V LVM; means 8E for MBR and
391 E6D6D379-F507-44C2-A23C-238F2A3DF928 for GPT
392 The default type value is L
394 bootable is specified as [*|-], with as default not-bootable.
396 The value of this field is irrelevant for Linux - when Linux
397 runs it has been booted already - but it might play a role for
398 certain boot loaders and for other operating systems.
399 Named-fields format
401 This format is more readable, robust, extensible and allows to
402 specify additional information (e.g., a UUID). It is recom‐
403 mended to use this format to keep your scripts more readable.
404 [device :] name[=value], ...
406 The device field is optional. sfdisk extracts the partition
408 number from the device name. It allows to specify the parti‐
409 tions in random order. This functionality is mostly used by
410 --dump. Don't use it if you are not sure.
411 The value can be between quotation marks (e.g., name="This is
413 partition name"). The currently supported fields are:
414 start=number
416 The first non-assigned sector aligned according to
417 device I/O limits. The default start offset for
418 the first partition is 1 MiB. The offset may be
419 followed by the multiplicative suffixes (KiB, MiB,
420 GiB, TiB, PiB, EiB, ZiB and YiB) then the number
421 is interpreted as offset in bytes.
422 size=number
424 Specify the partition size in sectors. The number
425 may be followed by the multiplicative suffixes
426 (KiB, MiB, GiB, TiB, PiB, EiB, ZiB and YiB), then
427 it's interpreted as size in bytes and the size is
428 aligned according to device I/O limits.
429 bootable
431 Mark the partition as bootable.
432 attrs=string
434 Partition attributes, usually GPT partition
435 attribute bits. See --part-attrs for more details
436 about the GPT-bits string format.
437 uuid=string
439 GPT partition UUID.
440 name=string
442 GPT partition name.
443 type=code
445 A hexadecimal number (without 0x) for an MBR par‐
446 tition, a GUID for a GPT partition, or a shortcut
447 as for unnamed-fields format. For backward com‐
448 patibility the Id= field has the same meaning.
449
452 sfdisk does not create partition table without partitions by default.
453 The lines with partitions are expected in the script by default. The
454 empty partition table has to be explicitly requested by "label: <name>"
455 script header line without any partitions lines. For example:
456 echo 'label: gpt' | sfdisk /dev/sdb
458 creates empty GPT partition table. Note that the --append disables this
460 feature.
461
464 It is recommended to save the layout of your devices. sfdisk supports
465 two ways.
466 Use the --dump option to save a description of the device layout to a
468 text file. The dump format is suitable for later sfdisk input. For
469 example:
470 sfdisk --dump /dev/sda > sda.dump
472 This can later be restored by:
474 sfdisk /dev/sda < sda.dump
476 If you want to do a full (binary) backup of all sectors where the par‐
478 tition table is stored, then use the --backup option. It writes the
479 sectors to ~/sfdisk-<device>-<offset>.bak files. The default name of
480 the backup file can be changed with the --backup-file option. The
481 backup files contain only raw data from the device. Note that the same
482 concept of backup files is used by wipefs(8). For example:
483 sfdisk --backup /dev/sda
485 The GPT header can later be restored by:
487 dd if=~/sfdisk-sda-0x00000200.bak of=/dev/sda \
489 seek=$((0x00000200)) bs=1 conv=notrunc
490 Note that sfdisk since version 2.26 no longer provides the -I option to
492 restore sectors. dd(1) provides all necessary functionality.
493
496 Implicit coloring can be disabled by an empty file /etc/terminal-col‐
497 ors.d/sfdisk.disable.
498 See terminal-colors.d(5) for more details about colorization configura‐
500 tion. The logical color names supported by sfdisk are:
501 header The header of the output tables.
503 warn The warning messages.
505 welcome
507 The welcome message.
508
511 Since version 2.26 sfdisk no longer provides the -R or --re-read option
512 to force the kernel to reread the partition table. Use blockdev
513 --rereadpt instead.
514 Since version 2.26 sfdisk does not provide the --DOS, --IBM,
516 --DOS-extended, --unhide, --show-extended, --cylinders, --heads, --sec‐
517 tors, --inside-outer, --not-inside-outer options.
518
521 SFDISK_DEBUG=all
522 enables sfdisk debug output.
523 LIBFDISK_DEBUG=all
525 enables libfdisk debug output.
526 LIBBLKID_DEBUG=all
528 enables libblkid debug output.
529 LIBSMARTCOLS_DEBUG=all
531 enables libsmartcols debug output.
532
535 fdisk(8), cfdisk(8), parted(8), partprobe(8), partx(8)
536
539 Karel Zak <kzak@redhat.com>
540 The current sfdisk implementation is based on the original sfdisk from
542 Andries E. Brouwer.
543
546 The sfdisk command is part of the util-linux package and is available
547 from https://www.kernel.org/pub/linux/utils/util-linux/.
548util-linux June 2015 SFDISK(8)