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.
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 If no partition-number is specified, then list the partitions
83 with an enabled flag.
84 --delete device [partition-number...]
86 Delete all or the specified partitions.
87 -d, --dump device
89 Dump the partitions of a device in a format that is usable as
90 input to sfdisk. See the section BACKING UP THE PARTITION TA‐
91 BLE.
92 -g, --show-geometry [device...]
94 List the geometry of all or the specified devices. For backward
95 compatibility the deprecated option --show-pt-geometry have the
96 same meaning as this one.
97 -J, --json device
99 Dump the partitions of a device in JSON format. Note that
100 sfdisk is not able to use JSON as input format.
101 -l, --list [device...]
103 List the partitions of all or the specified devices. This com‐
104 mand can be used together with --verify.
105 -F, --list-free [device...]
107 List the free unpartitioned areas on all or the specified
108 devices.
109 --part-attrs device partition-number [attributes]
111 Change the GPT partition attribute bits. If attributes is not
112 specified, then print the current partition settings. The
113 attributes argument is a comma- or space-delimited list of bits.
114 The currently supported attribute bits are: RequiredPartition,
115 NoBlockIOProtocol, LegacyBIOSBootable and GUID-specific bits in
116 the range from 48 to 63. For example, the string "RequiredPar‐
117 tition,50,51" sets three bits.
118 --part-label device partition-number [label]
120 Change the GPT partition name (label). If label is not speci‐
121 fied, then print the current partition label.
122 --part-type device partition-number [type]
124 Change the partition type. If type is not specified, then print
125 the current partition type. The type argument is hexadecimal
126 for MBR, or a GUID for GPT. For backward compatibility the
127 options -c and --id have the same meaning as this one.
128 --part-uuid device partition-number [uuid]
130 Change the GPT partition UUID. If uuid is not specified, then
131 print the current partition UUID.
132 -r, --reorder device
134 Renumber the partitions, ordering them by their start offset.
135 -s, --show-size [device...]
137 List the sizes of all or the specified devices in units of 1024
138 byte size. This command is DEPRECATED in favour of blockdev(1).
139 -T, --list-types
141 Print all supported types for the current disk label or the
142 label specified by --label.
143 -V, --verify [device...]
145 Test whether the partition table and partitions seem correct.
146
149 -a, --append
150 Don't create a new partition table, but only append the speci‐
151 fied partitions.
152 -b, --backup
154 Back up the current partition table sectors before starting the
155 partitioning. The default backup file name is
156 ~/sfdisk-<device>-<offset>.bak; to use another name see option
157 -O, --backup-file.
158 --color[=when]
160 Colorize the output. The optional argument when can be auto,
161 never or always. If the when argument is omitted, it defaults
162 to auto. The colors can be disabled; for the current built-in
163 default see the --help output. See also the COLORS section.
164 -f, --force
166 Disable all consistency checking.
167 --Linux
169 Deprecated and ignored option. Partitioning that is compatible
170 with Linux (and other modern operating systems) is the default.
171 -n, --no-act
173 Do everything except writing to the device.
174 --no-reread
176 Do not check through the re-read-partition-table ioctl whether
177 the device is in use.
178 --no-tell-kernel
180 Don't tell the kernel about partition changes. This option is
181 recommended together with --no-reread to modify a partition on
182 used disk. The modified partition should not be used (e.g.
183 mounted).
184 -O, --backup-file path
186 Override the default backup file name. Note that the device
187 name and offset are always appended to the file name.
188 --move-data[=path]
190 Move data after partition relocation, for example when moving
191 the beginning of a partition to another place on the disk. The
192 size of the partition has to remain the same, the new and old
193 location may overlap. This option requires option -N in order
194 to be processed on one specific partition only.
195 The path overrides the default log file name (the default is
197 ~/sfdisk-<devname>.move). The log file contains information
198 about all read/write operations on the partition data.
199 Note that this operation is risky and not atomic. Don't forget
201 to backup your data!
202 In the example below, the first command creates a 100MiB free
204 area before the first partition and moves the data it contains
205 (e.g. a filesystem), the next command creates a new partition
206 from the free space (at offset 2048), and the last command
207 reorders partitions to match disk order (the original sdc1 will
208 become sdc2).
209 echo '+100M,' | sfdisk --move-data /dev/sdc -N 1
211 echo '2048,' | sfdisk /dev/sdc --append
212 sfdisk /dev/sdc --reorder
213 -o, --output list
217 Specify which output columns to print. Use --help to get a list
218 of all supported columns.
219 The default list of columns may be extended if list is specified
221 in the format +list (e.g. -o +UUID).
222 -q, --quiet
224 Suppress extra info messages.
225 -u, --unit S
227 Deprecated option. Only the sector unit is supported. This
228 option is not supported when using the --show-size command.
229 -X, --label type
231 Specify the disk label type (e.g. dos, gpt, ...). If this
232 option is not given, then sfdisk defaults to the existing label,
233 but if there is no label on the device yet, then the type
234 defaults to dos. The default or the current label may be over‐
235 written by the "label: <name>" script header line. The option
236 --label does not force sfdisk to create empty disk label (see
237 the EMPTY DISK LABEL section below).
238 -Y, --label-nested type
240 Force editing of a nested disk label. The primary disk label
241 has to exist already. This option allows to edit for example a
242 hybrid/protective MBR on devices with GPT.
243 -w, --wipe when
246 Wipe filesystem, RAID and partition-table signatures from the
247 device, in order to avoid possible collisions. The argument
248 when can be auto, never or always. When this option is not
249 given, the default is auto, in which case signatures are wiped
250 only when in interactive mode; except the old partition-table
251 signatures which are always wiped before create a new partition-
252 table if the argument when is not never. In all cases detected
253 signatures are reported by warning messages before a new parti‐
254 tion table is created. See also wipefs(8) command.
255 -W, --wipe-partitions when
258 Wipe filesystem, RAID and partition-table signatures from a
259 newly created partitions, in order to avoid possible collisions.
260 The argument when can be auto, never or always. When this
261 option is not given, the default is auto, in which case signa‐
262 tures are wiped only when in interactive mode and after confir‐
263 mation by user. In all cases detected signatures are reported
264 by warning messages after a new partition is created. See also
265 wipefs(8) command.
266 -v, --version
269 Display version information and exit.
270 -h, --help
272 Display help text and exit.
273
276 sfdisk supports two input formats and generic header lines.
277 Header lines
279 The optional header lines specify generic information that apply
280 to the partition table. The header-line format is:
281 <name>: <value>
283 The currently recognized headers are:
285 unit Specify the partitioning unit. The only supported
287 unit is sectors.
288 label Specify the partition table type. For example dos
290 or gpt.
291 label-id
293 Specify the partition table identifier. It should
294 be a hexadecimal number (with a 0x prefix) for
295 MBR and a UUID for GPT.
296 Note that it is only possible to use header lines before the
298 first partition is specified in the input.
299 Unnamed-fields format
301 start size type bootable
303 where each line fills one partition descriptor.
305 Fields are separated by whitespace, comma or semicolon possibly
307 followed by whitespace; initial and trailing whitespace is
308 ignored. Numbers can be octal, decimal or hexadecimal; decimal
309 is the default. When a field is absent, empty or specified as
310 '-' a default value is used. But when the -N option (change a
311 single partition) is given, the default for each field is its
312 previous value.
313 The default value of start is the first non-assigned sector
315 aligned according to device I/O limits. The default start off‐
316 set for the first partition is 1 MiB. The offset may be fol‐
317 lowed by the multiplicative suffixes (KiB, MiB, GiB, TiB, PiB,
318 EiB, ZiB and YiB) then the number is interpreted as offset in
319 bytes.
320 The default value of size indicates "as much as possible"; i.e.
322 until the next partition or end-of-device. A numerical argument
323 is by default interpreted as a number of sectors, however if the
324 size is followed by one of the multiplicative suffixes (KiB,
325 MiB, GiB, TiB, PiB, EiB, ZiB and YiB) then the number is inter‐
326 preted as the size of the partition in bytes and it is then
327 aligned according to the device I/O limits. A '+' can be used
328 instead of a number to enlarge the partition as much as possi‐
329 ble. Note '+' is equivalent to the default behaviour for a new
330 partition; existing partitions will be resized as required.
331 The partition type is given in hex for MBR (DOS), without the 0x
333 prefix, a GUID string for GPT, or a shortcut:
334 L Linux; means 83 for MBR and
336 0FC63DAF-8483-4772-8E79-3D69D8477DE4 for GPT.
337 S swap area; means 82 for MBR and 0657FD6D-
339 A4AB-43C4-84E5-0933C84B4F4F for GPT
340 E extended partition; means 5 for MBR
342 H home partition; means
344 933AC7E1-2EB4-4F13-B844-0E14E2AEF915 for GPT
345 X linux extended partition; means 85 for MBR.
347 U EFI System partition, means EF for MBR and
349 C12A7328-F81F-11D2-BA4B-00A0C93EC93B for GPT
350 R Linux RAID; means FD for MBR and
352 A19D880F-05FC-4D3B-A006-743F0F84911E for GPT
353 V LVM; means 8E for MBR and
355 E6D6D379-F507-44C2-A23C-238F2A3DF928 for GPT
356 The default type value is L
358 bootable is specified as [*|-], with as default not-bootable.
360 The value of this field is irrelevant for Linux - when Linux
361 runs it has been booted already - but ir might play a role for
362 certain boot loaders and for other operating systems.
363 Named-fields format
365 This format is more readable, robust, extensible and allows to
366 specify additional information (e.g. a UUID). It is recommended
367 to use this format to keep your scripts more readable.
368 [device :] name[=value], ...
370 The device field is optional. sfdisk extracts the partition
372 number from the device name. It allows to specify the parti‐
373 tions in random order. This functionality is mostly used by
374 --dump. Don't use it if you are not sure.
375 The value can be between quotation marks (e.g. name="This is
377 partition name"). The currently supported fields are:
378 start=number
380 The first non-assigned sector aligned according to
381 device I/O limits. The default start offset for
382 the first partition is 1 MiB. The offset may be
383 followed by the multiplicative suffixes (KiB, MiB,
384 GiB, TiB, PiB, EiB, ZiB and YiB) then the number
385 is interpreted as offset in bytes.
386 size=number
388 Specify the partition size in sectors. The number
389 may be followed by the multiplicative suffixes
390 (KiB, MiB, GiB, TiB, PiB, EiB, ZiB and YiB), then
391 it's interpreted as size in bytes and the size is
392 aligned according to device I/O limits.
393 bootable
395 Mark the partition as bootable.
396 attrs=string
398 Partition attributes, usually GPT partition
399 attribute bits. See --part-attrs for more details
400 about the GPT-bits string format.
401 uuid=string
403 GPT partition UUID.
404 name=string
406 GPT partition name.
407 type=code
409 A hexadecimal number (without 0x) for an MBR par‐
410 tition, or a GUID for a GPT partition. For back‐
411 ward compatibility the Id= field has the same
412 meaning.
413
416 sfdisk does not create partition table without partitions by default.
417 The lines with partitions are expected in the script by default. The
418 empty partition table has to be explicitly requested by "label: <name>"
419 script header line without any partitions lines. For example:
420 echo 'label: gpt' | sfdisk /dev/sdb
422 creates empty GPT partition table. Note that the --append disables this
424 feature.
425
428 It is recommended to save the layout of your devices. sfdisk supports
429 two ways.
430 Use the --dump option to save a description of the device layout to a
432 text file. The dump format is suitable for later sfdisk input. For
433 example:
434 sfdisk --dump /dev/sda > sda.dump
436 This can later be restored by:
438 sfdisk /dev/sda < sda.dump
440 If you want to do a full (binary) backup of all sectors where the par‐
442 tition table is stored, then use the --backup option. It writes the
443 sectors to ~/sfdisk-<device>-<offset>.bak files. The default name of
444 the backup file can be changed with the --backup-file option. The
445 backup files contain only raw data from the device. Note that the same
446 concept of backup files is used by wipefs(8). For example:
447 sfdisk --backup /dev/sda
449 The GPT header can later be restored by:
451 dd if=~/sfdisk-sda-0x00000200.bak of=/dev/sda \
453 seek=$((0x00000200)) bs=1 conv=notrunc
454 Note that sfdisk since version 2.26 no longer provides the -I option to
456 restore sectors. dd(1) provides all necessary functionality.
457
460 Implicit coloring can be disabled by an empty file /etc/terminal-col‐
461 ors.d/sfdisk.disable.
462 See terminal-colors.d(5) for more details about colorization configura‐
464 tion. The logical color names supported by sfdisk are:
465 header The header of the output tables.
467 warn The warning messages.
469 welcome
471 The welcome message.
472
475 Since version 2.26 sfdisk no longer provides the -R or --re-read option
476 to force the kernel to reread the partition table. Use blockdev
477 --rereadpt instead.
478 Since version 2.26 sfdisk does not provide the --DOS, --IBM,
480 --DOS-extended, --unhide, --show-extended, --cylinders, --heads, --sec‐
481 tors, --inside-outer, --not-inside-outer options.
482
485 SFDISK_DEBUG=all
486 enables sfdisk debug output.
487 LIBFDISK_DEBUG=all
489 enables libfdisk debug output.
490 LIBBLKID_DEBUG=all
492 enables libblkid debug output.
493 LIBSMARTCOLS_DEBUG=all
495 enables libsmartcols debug output.
496
499 fdisk(8), cfdisk(8), parted(8), partprobe(8), partx(8)
500
503 Karel Zak <kzak@redhat.com>
504 The current sfdisk implementation is based on the original sfdisk from
506 Andries E. Brouwer.
507
510 The sfdisk command is part of the util-linux package and is available
511 from https://www.kernel.org/pub/linux/utils/util-linux/.
512util-linux June 2015 SFDISK(8)