1SFDISK(8) System Administration SFDISK(8)
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6 sfdisk - display or manipulate a disk partition table
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9 sfdisk [options] device [-N partition-number]
10 sfdisk [options] command
12
14 sfdisk is a script-oriented tool for partitioning any block device.
15 Since version 2.26 sfdisk supports MBR (DOS), GPT, SUN and SGI disk
17 labels, but no longer provides any functionality for CHS (Cylinder-
18 Head-Sector) addressing. CHS has never been important for Linux, and
19 this addressing concept does not make any sense for new devices.
20 sfdisk (since version 2.26) aligns the start and end of partitions to
22 block-device I/O limits when relative sizes are specified, when the
23 default values are used or when multiplicative suffixes (e.g. MiB) are
24 used for sizes. It is possible that partition size will be optimized
25 (reduced or enlarged) due to alignment if the start offset is specified
26 exactly in sectors and partition size relative or by multiplicative
27 suffixes.
28 The recommended way is not to specify start offsets at all and specify
30 partition size in MiB, GiB (or so). In this case sfdisk align all par‐
31 titions to block-device I/O limits (or when I/O limits are too small
32 then to megabyte boundary to keep disk layout portable). If this
33 default behaviour is unwanted (usually for very small partitions) then
34 specify offsets and sizes in sectors. In this case sfdisk entirely
35 follows specified numbers without any optimization.
36 sfdisk does not create the standard system partitions for SGI and SUN
38 disk labels like fdisk(8) does. It is necessary to explicitly create
39 all partitions including whole-disk system partitions.
40 sfdisk uses BLKRRPART (reread partition table) ioctl to make sure that
42 the device is not used by system or another tools (see also --no-
43 reread). It's possible that this feature or another sfdisk activity
44 races with udevd. The recommended way how to avoid possible collisions
45 is to use exclusive flock for the whole-disk device to serialize device
46 access. The exclusive lock will cause udevd to skip the event handling
47 on the device. For example:
48 flock /dev/sdc sfdisk /dev/sdc
50 Note, this semantic is not currently supported by udevd for MD and DM
52 devices.
53
56 The commands are mutually exclusive.
57 [-N partition-number] device
59 The default sfdisk command is to read the specification for the
60 desired partitioning of device from standard input, and then
61 create a partition table according to the specification. See
62 below for the description of the input format. If standard
63 input is a terminal, then sfdisk starts an interactive session.
64 If the option -N is specified, then the changes are applied to
66 the partition addressed by partition-number. The unspecified
67 fields of the partition are not modified.
68 Note that it's possible to address an unused partition with -N.
70 For example, an MBR always contains 4 partitions, but the number
71 of used partitions may be smaller. In this case sfdisk follows
72 the default values from the partition table and does not use
73 built-in defaults for the unused partition given with -N. See
74 also --append.
75 -A, --activate device [partition-number...]
77 Switch on the bootable flag for the specified partitions and
78 switch off the bootable flag on all unspecified partitions. The
79 special placeholder '-' may be used instead of the partition
80 numbers to switch off the bootable flag on all partitions.
81 The activation command is supported for MBR and PMBR only. If
83 GPT label is detected than sfdisk prints warning and automati‐
84 cally enter PMBR.
85 If no partition-number is specified, then list the partitions
87 with an enabled flag.
88 --delete device [partition-number...]
90 Delete all or the specified partitions.
91 -d, --dump device
93 Dump the partitions of a device in a format that is usable as
94 input to sfdisk. See the section BACKING UP THE PARTITION TA‐
95 BLE.
96 -g, --show-geometry [device...]
98 List the geometry of all or the specified devices. For backward
99 compatibility the deprecated option --show-pt-geometry have the
100 same meaning as this one.
101 -J, --json device
103 Dump the partitions of a device in JSON format. Note that
104 sfdisk is not able to use JSON as input format.
105 -l, --list [device...]
107 List the partitions of all or the specified devices. This com‐
108 mand can be used together with --verify.
109 -F, --list-free [device...]
111 List the free unpartitioned areas on all or the specified
112 devices.
113 --part-attrs device partition-number [attributes]
115 Change the GPT partition attribute bits. If attributes is not
116 specified, then print the current partition settings. The
117 attributes argument is a comma- or space-delimited list of bits.
118 The currently supported attribute bits are: RequiredPartition,
119 NoBlockIOProtocol, LegacyBIOSBootable and GUID-specific bits in
120 the range from 48 to 63. For example, the string "RequiredPar‐
121 tition,50,51" sets three bits.
122 --part-label device partition-number [label]
124 Change the GPT partition name (label). If label is not speci‐
125 fied, then print the current partition label.
126 --part-type device partition-number [type]
128 Change the partition type. If type is not specified, then print
129 the current partition type. The type argument is hexadecimal
130 for MBR, or a GUID for GPT. For backward compatibility the
131 options -c and --id have the same meaning as this one.
132 --part-uuid device partition-number [uuid]
134 Change the GPT partition UUID. If uuid is not specified, then
135 print the current partition UUID.
136 -r, --reorder device
138 Renumber the partitions, ordering them by their start offset.
139 -s, --show-size [device...]
141 List the sizes of all or the specified devices in units of 1024
142 byte size. This command is DEPRECATED in favour of blockdev(1).
143 -T, --list-types
145 Print all supported types for the current disk label or the
146 label specified by --label.
147 -V, --verify [device...]
149 Test whether the partition table and partitions seem correct.
150
153 -a, --append
154 Don't create a new partition table, but only append the speci‐
155 fied partitions.
156 -b, --backup
158 Back up the current partition table sectors before starting the
159 partitioning. The default backup file name is
160 ~/sfdisk-<device>-<offset>.bak; to use another name see option
161 -O, --backup-file.
162 --color[=when]
164 Colorize the output. The optional argument when can be auto,
165 never or always. If the when argument is omitted, it defaults
166 to auto. The colors can be disabled; for the current built-in
167 default see the --help output. See also the COLORS section.
168 -f, --force
170 Disable all consistency checking.
171 --Linux
173 Deprecated and ignored option. Partitioning that is compatible
174 with Linux (and other modern operating systems) is the default.
175 -n, --no-act
177 Do everything except writing to the device.
178 --no-reread
180 Do not check through the re-read-partition-table ioctl whether
181 the device is in use.
182 --no-tell-kernel
184 Don't tell the kernel about partition changes. This option is
185 recommended together with --no-reread to modify a partition on
186 used disk. The modified partition should not be used (e.g.
187 mounted).
188 -O, --backup-file path
190 Override the default backup file name. Note that the device
191 name and offset are always appended to the file name.
192 --move-data[=path]
194 Move data after partition relocation, for example when moving
195 the beginning of a partition to another place on the disk. The
196 size of the partition has to remain the same, the new and old
197 location may overlap. This option requires option -N in order
198 to be processed on one specific partition only.
199 The path overrides the default log file name (the default is
201 ~/sfdisk-<devname>.move). The log file contains information
202 about all read/write operations on the partition data.
203 Note that this operation is risky and not atomic. Don't forget
205 to backup your data!
206 In the example below, the first command creates a 100MiB free
208 area before the first partition and moves the data it contains
209 (e.g. a filesystem), the next command creates a new partition
210 from the free space (at offset 2048), and the last command
211 reorders partitions to match disk order (the original sdc1 will
212 become sdc2).
213 echo '+100M,' | sfdisk --move-data /dev/sdc -N 1
215 echo '2048,' | sfdisk /dev/sdc --append
216 sfdisk /dev/sdc --reorder
217 -o, --output list
221 Specify which output columns to print. Use --help to get a list
222 of all supported columns.
223 The default list of columns may be extended if list is specified
225 in the format +list (e.g. -o +UUID).
226 -q, --quiet
228 Suppress extra info messages.
229 -u, --unit S
231 Deprecated option. Only the sector unit is supported. This
232 option is not supported when using the --show-size command.
233 -X, --label type
235 Specify the disk label type (e.g. dos, gpt, ...). If this
236 option is not given, then sfdisk defaults to the existing label,
237 but if there is no label on the device yet, then the type
238 defaults to dos. The default or the current label may be over‐
239 written by the "label: <name>" script header line. The option
240 --label does not force sfdisk to create empty disk label (see
241 the EMPTY DISK LABEL section below).
242 -Y, --label-nested type
244 Force editing of a nested disk label. The primary disk label
245 has to exist already. This option allows to edit for example a
246 hybrid/protective MBR on devices with GPT.
247 -w, --wipe when
250 Wipe filesystem, RAID and partition-table signatures from the
251 device, in order to avoid possible collisions. The argument
252 when can be auto, never or always. When this option is not
253 given, the default is auto, in which case signatures are wiped
254 only when in interactive mode; except the old partition-table
255 signatures which are always wiped before create a new partition-
256 table if the argument when is not never. In all cases detected
257 signatures are reported by warning messages before a new parti‐
258 tion table is created. See also wipefs(8) command.
259 -W, --wipe-partitions when
262 Wipe filesystem, RAID and partition-table signatures from a
263 newly created partitions, in order to avoid possible collisions.
264 The argument when can be auto, never or always. When this
265 option is not given, the default is auto, in which case signa‐
266 tures are wiped only when in interactive mode and after confir‐
267 mation by user. In all cases detected signatures are reported
268 by warning messages after a new partition is created. See also
269 wipefs(8) command.
270 -v, --version
273 Display version information and exit.
274 -h, --help
276 Display help text and exit.
277
280 sfdisk supports two input formats and generic header lines.
281 Header lines
283 The optional header lines specify generic information that apply
284 to the partition table. The header-line format is:
285 <name>: <value>
287 The currently recognized headers are:
289 unit Specify the partitioning unit. The only supported
291 unit is sectors.
292 label Specify the partition table type. For example dos
294 or gpt.
295 label-id
297 Specify the partition table identifier. It should
298 be a hexadecimal number (with a 0x prefix) for
299 MBR and a UUID for GPT.
300 first-lba
302 Specify the first usable sector for GPT parti‐
303 tions.
304 last-lba
306 Specify the last usable sector for GPT partitions.
307 table-length
309 Specify the maximal number of GPT partitions.
310 grain Specify minimal size in bytes used to calculate
312 partitions alignment. The default is 1MiB and
313 it's strongly recommended to use the default. Do
314 not modify this variable if you're not sure.
315 Note that it is only possible to use header lines before the
317 first partition is specified in the input.
318 Unnamed-fields format
320 start size type bootable
322 where each line fills one partition descriptor.
324 Fields are separated by whitespace, comma or semicolon possibly
326 followed by whitespace; initial and trailing whitespace is
327 ignored. Numbers can be octal, decimal or hexadecimal; decimal
328 is the default. When a field is absent, empty or specified as
329 '-' a default value is used. But when the -N option (change a
330 single partition) is given, the default for each field is its
331 previous value.
332 The default value of start is the first non-assigned sector
334 aligned according to device I/O limits. The default start off‐
335 set for the first partition is 1 MiB. The offset may be fol‐
336 lowed by the multiplicative suffixes (KiB, MiB, GiB, TiB, PiB,
337 EiB, ZiB and YiB) then the number is interpreted as offset in
338 bytes.
339 The default value of size indicates "as much as possible"; i.e.
341 until the next partition or end-of-device. A numerical argument
342 is by default interpreted as a number of sectors, however if the
343 size is followed by one of the multiplicative suffixes (KiB,
344 MiB, GiB, TiB, PiB, EiB, ZiB and YiB) then the number is inter‐
345 preted as the size of the partition in bytes and it is then
346 aligned according to the device I/O limits. A '+' can be used
347 instead of a number to enlarge the partition as much as possi‐
348 ble. Note '+' is equivalent to the default behaviour for a new
349 partition; existing partitions will be resized as required.
350 The partition type is given in hex for MBR (DOS), without the 0x
352 prefix, a GUID string for GPT, or a shortcut:
353 L Linux; means 83 for MBR and
355 0FC63DAF-8483-4772-8E79-3D69D8477DE4 for GPT.
356 S swap area; means 82 for MBR and 0657FD6D-
358 A4AB-43C4-84E5-0933C84B4F4F for GPT
359 E extended partition; means 5 for MBR
361 H home partition; means
363 933AC7E1-2EB4-4F13-B844-0E14E2AEF915 for GPT
364 X linux extended partition; means 85 for MBR.
366 U EFI System partition, means EF for MBR and
368 C12A7328-F81F-11D2-BA4B-00A0C93EC93B for GPT
369 R Linux RAID; means FD for MBR and
371 A19D880F-05FC-4D3B-A006-743F0F84911E for GPT
372 V LVM; means 8E for MBR and
374 E6D6D379-F507-44C2-A23C-238F2A3DF928 for GPT
375 The default type value is L
377 bootable is specified as [*|-], with as default not-bootable.
379 The value of this field is irrelevant for Linux - when Linux
380 runs it has been booted already - but ir might play a role for
381 certain boot loaders and for other operating systems.
382 Named-fields format
384 This format is more readable, robust, extensible and allows to
385 specify additional information (e.g. a UUID). It is recommended
386 to use this format to keep your scripts more readable.
387 [device :] name[=value], ...
389 The device field is optional. sfdisk extracts the partition
391 number from the device name. It allows to specify the parti‐
392 tions in random order. This functionality is mostly used by
393 --dump. Don't use it if you are not sure.
394 The value can be between quotation marks (e.g. name="This is
396 partition name"). The currently supported fields are:
397 start=number
399 The first non-assigned sector aligned according to
400 device I/O limits. The default start offset for
401 the first partition is 1 MiB. The offset may be
402 followed by the multiplicative suffixes (KiB, MiB,
403 GiB, TiB, PiB, EiB, ZiB and YiB) then the number
404 is interpreted as offset in bytes.
405 size=number
407 Specify the partition size in sectors. The number
408 may be followed by the multiplicative suffixes
409 (KiB, MiB, GiB, TiB, PiB, EiB, ZiB and YiB), then
410 it's interpreted as size in bytes and the size is
411 aligned according to device I/O limits.
412 bootable
414 Mark the partition as bootable.
415 attrs=string
417 Partition attributes, usually GPT partition
418 attribute bits. See --part-attrs for more details
419 about the GPT-bits string format.
420 uuid=string
422 GPT partition UUID.
423 name=string
425 GPT partition name.
426 type=code
428 A hexadecimal number (without 0x) for an MBR par‐
429 tition, or a GUID for a GPT partition. For back‐
430 ward compatibility the Id= field has the same
431 meaning.
432
435 sfdisk does not create partition table without partitions by default.
436 The lines with partitions are expected in the script by default. The
437 empty partition table has to be explicitly requested by "label: <name>"
438 script header line without any partitions lines. For example:
439 echo 'label: gpt' | sfdisk /dev/sdb
441 creates empty GPT partition table. Note that the --append disables this
443 feature.
444
447 It is recommended to save the layout of your devices. sfdisk supports
448 two ways.
449 Use the --dump option to save a description of the device layout to a
451 text file. The dump format is suitable for later sfdisk input. For
452 example:
453 sfdisk --dump /dev/sda > sda.dump
455 This can later be restored by:
457 sfdisk /dev/sda < sda.dump
459 If you want to do a full (binary) backup of all sectors where the par‐
461 tition table is stored, then use the --backup option. It writes the
462 sectors to ~/sfdisk-<device>-<offset>.bak files. The default name of
463 the backup file can be changed with the --backup-file option. The
464 backup files contain only raw data from the device. Note that the same
465 concept of backup files is used by wipefs(8). For example:
466 sfdisk --backup /dev/sda
468 The GPT header can later be restored by:
470 dd if=~/sfdisk-sda-0x00000200.bak of=/dev/sda \
472 seek=$((0x00000200)) bs=1 conv=notrunc
473 Note that sfdisk since version 2.26 no longer provides the -I option to
475 restore sectors. dd(1) provides all necessary functionality.
476
479 Implicit coloring can be disabled by an empty file /etc/terminal-col‐
480 ors.d/sfdisk.disable.
481 See terminal-colors.d(5) for more details about colorization configura‐
483 tion. The logical color names supported by sfdisk are:
484 header The header of the output tables.
486 warn The warning messages.
488 welcome
490 The welcome message.
491
494 Since version 2.26 sfdisk no longer provides the -R or --re-read option
495 to force the kernel to reread the partition table. Use blockdev
496 --rereadpt instead.
497 Since version 2.26 sfdisk does not provide the --DOS, --IBM,
499 --DOS-extended, --unhide, --show-extended, --cylinders, --heads, --sec‐
500 tors, --inside-outer, --not-inside-outer options.
501
504 SFDISK_DEBUG=all
505 enables sfdisk debug output.
506 LIBFDISK_DEBUG=all
508 enables libfdisk debug output.
509 LIBBLKID_DEBUG=all
511 enables libblkid debug output.
512 LIBSMARTCOLS_DEBUG=all
514 enables libsmartcols debug output.
515
518 fdisk(8), cfdisk(8), parted(8), partprobe(8), partx(8)
519
522 Karel Zak <kzak@redhat.com>
523 The current sfdisk implementation is based on the original sfdisk from
525 Andries E. Brouwer.
526
529 The sfdisk command is part of the util-linux package and is available
530 from https://www.kernel.org/pub/linux/utils/util-linux/.
531util-linux June 2015 SFDISK(8)