disk-utils/sfdisk.8

   1 .\" sfdisk.8 -- man page for sfdisk
   2 .\" Copyright (C) 2014 Karel Zak <kzak@redhat.com>
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  13 .TH SFDISK 8 "June 2015" "util-linux" "System Administration"
  14 .SH NAME
  15 sfdisk \- display or manipulate a disk partition table
  16 .SH SYNOPSIS
  17 .B sfdisk
  18 [options]
  19 .I device
  20 .RB [ \-N
  21 .IR partition-number ]
  22 .sp
  23 .B sfdisk
  24 [options]
  25 .I command
  26 .SH DESCRIPTION
  27 .B sfdisk
  28 is a script-oriented tool for partitioning any block device.
  29
  30 Since version 2.26
  31 .B sfdisk
  32 supports MBR (DOS), GPT, SUN and SGI disk labels, but no longer provides any
  33 functionality for CHS (Cylinder-Head-Sector) addressing.  CHS has
  34 never been important for Linux, and this addressing concept does not make any
  35 sense for new devices.
  36 .sp
  37 .B sfdisk
  38 (since version 2.26)
  39 .B aligns the start and end of partitions
  40 to block-device I/O limits when relative sizes are specified, when the default
  41 values are used or when multiplicative suffixes (e.g MiB) are used for sizes.
  42 It is possible that partition size will be optimized (reduced or enlarged) due
  43 to alignment if the start offset is specified exactly in sectors and partition
  44 size relative or by multiplicative suffixes.
  45
  46 The recommended way is not to specify start offsets at all and specify
  47 partition size in MiB, GiB (or so).  In this case sfdisk align all partitions
  48 to block-device I/O limits (or when I/O limits are too small then to megabyte
  49 boundary to keep disk layout portable).  If this default behaviour is unwanted
  50 (usually for very small partitions) then specify offsets and sizes in
  51 sectors.  In this case sfdisk entirely follows specified numbers without any
  52 optimization.
  53 .sp
  54 .B sfdisk
  55 does not create the standard system partitions for SGI and SUN disk labels like
  56 .BR fdisk (8)
  57 does.
  58 It is necessary to explicitly create all partitions including whole-disk system
  59 partitions.
  60
  61 .SH COMMANDS
  62 The commands are mutually exclusive.
  63 .TP
  64 .RB [ \-N " \fIpartition-number\fR] " \fIdevice\fR
  65 The default \fBsfdisk\fR command is to read the specification for the desired
  66 partitioning of \fIdevice\fR from standard input, and then create a partition
  67 table according to the specification.  See below for the description of the
  68 input format.  If standard input is a terminal, then \fBsfdisk\fR starts an
  69 interactive session.
  70 .sp
  71 If the option \fB\-N\fR is specified, then the changes are applied to
  72 the partition addressed by \fIpartition-number\fR.  The unspecified fields
  73 of the partition are not modified.
  74 .sp
  75 Note that it's possible to address an unused partition with \fB\-N\fR.
  76 For example, an MBR always contains 4 partitions, but the number of used
  77 partitions may be smaller.  In this case \fBsfdisk\fR follows the default
  78 values from the partition table and does not use built-in defaults for the
  79 unused partition given with \fB\-N\fR.  See also \fB\-\-append\fR.
  80 .TP
  81 .BR \-A , " \-\-activate \fIdevice " [ \fIpartition-number ...]
  82 Switch on the bootable flag for the specified partitions.
  83 If no \fIpartition-number\fR is specified,
  84 then list the partitions with an enabled flag.
  85 .TP
  86 .BR "\-\-delete \fIdevice " [ \fIpartition-number ...]
  87 Delete all or the specified partitions.
  88 .TP
  89 .BR \-d , " \-\-dump " \fIdevice\fR
  90 Dump the partitions of a device in a format that is usable as input to \fBsfdisk\fR.
  91 See the section \fBBACKING UP THE PARTITION TABLE\fR.
  92 .TP
  93 .BR \-g , " \-\-show\-geometry " [ \fIdevice ...]
  94 List the geometry of all or the specified devices. For backward
  95 compatibility the deprecated option \fB\-\-show\-pt\-geometry\fR have the same
  96 meaning as this one.
  97 .TP
  98 .BR \-J , " \-\-json " \fIdevice\fR
  99 Dump the partitions of a device in JSON format.  Note that \fBsfdisk\fR is
 100 not able to use JSON as input format.
 101 .TP
 102 .BR \-l , " \-\-list " [ \fIdevice ...]
 103 List the partitions of all or the specified devices.  This command can be used
 104 together with \fB\-\-verify\fR.
 105 .TP
 106 .BR \-F , " \-\-list-free " [ \fIdevice ...]
 107 List the free unpartitioned areas on all or the specified devices.
 108 .TP
 109 .BR "\-\-part\-attrs \fIdevice partition-number " [ \fIattributes ]
 110 Change the GPT partition attribute bits.  If \fIattributes\fR is not specified,
 111 then print the current partition settings.  The \fIattributes\fR argument is a
 112 comma- or space-delimited list of bits.  The currently supported attribute
 113 bits are: RequiredPartition, NoBlockIOProtocol, LegacyBIOSBootable
 114 and GUID-specific bits in the range from 48 to 63.  For example, the string
 115 "RequiredPartition,50,51" sets three bits.
 116 .TP
 117 .BR "\-\-part\-label \fIdevice partition-number " [ \fIlabel ]
 118 Change the GPT partition name (label).  If \fIlabel\fR is not specified,
 119 then print the current partition label.
 120 .TP
 121 .BR "\-\-part\-type \fIdevice partition-number " [ \fItype ]
 122 Change the partition type.  If \fItype\fR is not specified, then print the
 123 current partition type.  The \fItype\fR argument is hexadecimal for MBR,
 124 or a GUID for GPT.  For backward compatibility the options \fB\-c\fR and
 125 \fB\-\-id\fR have the same meaning as this one.
 126 .TP
 127 .BR "\-\-part\-uuid \fIdevice partition-number " [ \fIuuid ]
 128 Change the GPT partition UUID.  If \fIuuid\fR is not specified,
 129 then print the current partition UUID.
 130 .TP
 131 .BR \-r , " \-\-reorder " \fIdevice
 132 Renumber the partitions, ordering them by their start offset.
 133 .TP
 134 .BR \-s , " \-\-show\-size " [ \fIdevice ...]
 135 List the sizes of all or the specified devices in units of 1024 byte size.
 136 This command is DEPRECATED in favour of
 137 .BR blockdev (1).
 138 .TP
 139 .BR \-T , " \-\-list\-types"
 140 Print all supported types for the current disk label or the label specified by
 141 \fB\-\-label\fR.
 142 .TP
 143 .BR \-V , " \-\-verify " [ \fIdevice ...]
 144 Test whether the partition table and partitions seem correct.
 145
 146 .SH OPTIONS
 147 .TP
 148 .BR \-a , " \-\-append"
 149 Don't create a new partition table, but only append the specified partitions.
 150 .TP
 151 .BR \-b , " \-\-backup"
 152 Back up the current partition table sectors before starting the partitioning.
 153 The default backup file name is ~/sfdisk-<device>-<offset>.bak; to use another
 154 name see option \fB\-O\fR, \fB\-\-backup\-file\fR.
 155 .TP
 156 .BR \-\-color [ =\fIwhen ]
 157 Colorize the output.  The optional argument \fIwhen\fP
 158 can be \fBauto\fR, \fBnever\fR or \fBalways\fR.  If the \fIwhen\fR argument is omitted,
 159 it defaults to \fBauto\fR.  The colors can be disabled; for the current built-in default
 160 see the \fB\-\-help\fR output.  See also the \fBCOLORS\fR section.
 161 .TP
 162 .BR \-f , " \-\-force"
 163 Disable all consistency checking.
 164 .TP
 165 .BR \-\-Linux
 166 Deprecated and ignored option.  Partitioning that is compatible with
 167 Linux (and other modern operating systems) is the default.
 168 .TP
 169 .BR \-n , " \-\-no\-act"
 170 Do everything except writing to the device.
 171 .TP
 172 .B \-\-no\-reread
 173 Do not check through the re-read-partition-table ioctl whether the device is in use.
 174 .TP
 175 .B \-\-no\-tell\-kernel
 176 Don't tell the kernel about partition changes. This option is recommended together
 177 with \fB\-\-no\-reread\fR to modify a partition on used disk. The modified partition
 178 should not be used (e.g. mounted).
 179 .TP
 180 .BR \-O , " \-\-backup\-file " \fIpath
 181 Override the default backup file name.  Note that the device name and offset
 182 are always appended to the file name.
 183 .TP
 184 .BR \-\-move-data [ =\fIpath ]
 185 Move data after partition relocation, for example when moving the beginning
 186 of a partition to another place on the disk.  The size of the partition has
 187 to remain the same, the new and old location may overlap.  This option requires
 188 option \fB\-N\fR in order to be processed on one specific partition only.
 189
 190 The \fIpath\fR overrides the default log file name
 191 (the default is ~/sfdisk-<devname>.move).  The log file contains information
 192 about all read/write operations on the partition data.
 193
 194 Note that this operation is risky and not atomic. \fBDon't forget to backup your data!\fR
 195
 196 In the example below, the first command creates a 100MiB free area before
 197 the first partition and moves the data it contains (e.g. a filesystem),
 198 the next command creates a new partition from the free space (at offset 2048),
 199 and the last command reorders partitions to match disk order
 200 (the original sdc1 will become sdc2).
 201 .RS
 202 .sp
 203 .B "echo '+100M,' | sfdisk --move-data /dev/sdc -N 1"
 204 .br
 205 .B "echo '2048,' | sfdisk /dev/sdc --append
 206 .br
 207 .B sfdisk /dev/sdc --reorder
 208 .sp
 209 .RE
 210
 211 .TP
 212 .BR \-o , " \-\-output " \fIlist
 213 Specify which output columns to print.  Use
 214 .B \-\-help
 215 to get a list of all supported columns.
 216 .sp
 217 The default list of columns may be extended if \fIlist\fP is
 218 specified in the format \fI+list\fP (e.g. \fB-o +UUID\fP).
 219 .TP
 220 .BR \-q , " \-\-quiet"
 221 Suppress extra info messages.
 222 .TP
 223 .BR \-u , " \-\-unit S"
 224 Deprecated option.  Only the sector unit is supported. This option is not
 225 supported when using the --show-size command.
 226 .TP
 227 .BR \-X , " \-\-label " \fItype
 228 Specify the disk label type (e.g. \fBdos\fR, \fBgpt\fR, ...).  If this option
 229 is not given, then \fBsfdisk\fR defaults to the existing label, but if there
 230 is no label on the device yet, then the type defaults to \fBdos\fR. The default
 231 or the current label may be overwritten by the "label: <name>" script header
 232 line. The option \fB\-\-label\fR does not force \fBsfdisk\fR to create empty
 233 disk label (see the \fBEMPTY DISK LABEL\fR section below).
 234 .TP
 235 .BR \-Y , " \-\-label\-nested " \fItype
 236 Force editing of a nested disk label.  The primary disk label has to exist already.
 237 This option allows to edit for example a hybrid/protective MBR on devices with GPT.
 238
 239 .TP
 240 .BR -w , " \-\-wipe "\fIwhen
 241 Wipe filesystem, RAID and partition-table signatures from the device, in order
 242 to avoid possible collisions.  The argument \fIwhen\fR can be \fBauto\fR,
 243 \fBnever\fR or \fBalways\fR.  When this option is not given, the default is
 244 \fBauto\fR, in which case signatures are wiped only when in interactive mode;
 245 except the old partition-table signatures which are always wiped before create
 246 a new partition-table if the argument \fIwhen\fR is not \fBnever\fR. In all
 247 cases detected signatures are reported by warning messages before a new
 248 partition table is created.  See also
 249 .BR wipefs (8)
 250 command.
 251
 252 .TP
 253 .BR -W , " \-\-wipe-partitions "\fIwhen
 254 Wipe filesystem, RAID and partition-table signatures from a newly created
 255 partitions, in order to avoid possible collisions.  The argument \fIwhen\fR can
 256 be \fBauto\fR, \fBnever\fR or \fBalways\fR.  When this option is not given, the
 257 default is \fBauto\fR, in which case signatures are wiped only when in
 258 interactive mode and after confirmation by user.  In all cases detected
 259 signatures are reported by warning messages after a new partition is created.
 260 See also
 261 .BR wipefs (8)
 262 command.
 263
 264 .TP
 265 .BR \-v , " \-\-version"
 266 Display version information and exit.
 267 .TP
 268 .BR \-h , " \-\-help"
 269 Display help text and exit.
 270
 271 .SH "INPUT FORMATS"
 272 .B sfdisk
 273 supports two input formats and generic header lines.
 274
 275 .B Header lines
 276 .RS
 277 The optional header lines specify generic information that apply to the partition
 278 table.  The header-line format is:
 279 .RS
 280 .sp
 281 .B "<name>: <value>"
 282 .sp
 283 .RE
 284 The currently recognized headers are:
 285 .RS
 286 .TP
 287 .B unit
 288 Specify the partitioning unit.  The only supported unit is \fBsectors\fR.
 289 .TP
 290 .B label
 291 Specify the partition table type.  For example \fBdos\fR or \fBgpt\fR.
 292 .TP
 293 .B label-id
 294 Specify the partition table identifier.  It should be a  hexadecimal number
 295 (with a 0x prefix) for MBR and a UUID for GPT.
 296 .RE
 297 .sp
 298 Note that it is only possible to use header lines before the first partition
 299 is specified in the input.
 300 .RE
 301
 302 .B Unnamed-fields format
 303 .RS
 304 .RS
 305 .sp
 306 .I start size type bootable
 307 .sp
 308 .RE
 309 where each line fills one partition descriptor.
 310 .sp
 311 Fields are separated by whitespace, comma or semicolon possibly
 312 followed by whitespace; initial and trailing whitespace is ignored.
 313 Numbers can be octal, decimal or hexadecimal; decimal is the default.
 314 When a field is absent, empty or specified as '-' a default value is
 315 used.  But when the \fB-N\fR option (change a single partition) is
 316 given, the default for each field is its previous value.
 317 .sp
 318 The default value of
 319 .I start
 320 is the first non-assigned sector aligned according to device I/O limits.
 321 The default start offset for the first partition is 1 MiB.  The offset may
 322 be followed by the multiplicative suffixes (KiB, MiB, GiB, TiB, PiB,
 323 EiB, ZiB and YiB) then the number is interpreted as offset in bytes.
 324 .sp
 325 The default value of
 326 .I size
 327 indicates "as much as possible"; i.e. until the next partition or
 328 end-of-device.  A numerical argument is by default interpreted as a
 329 number of sectors, however if the size is followed by one of the
 330 multiplicative suffixes (KiB, MiB, GiB, TiB, PiB, EiB, ZiB and YiB)
 331 then the number is interpreted as the size of the partition in bytes
 332 and it is then aligned according to the device I/O limits.  A '+' can
 333 be used instead of a number to enlarge the partition as much as
 334 possible.  Note '+' is equivalent to the default behaviour for a new
 335 partition; existing partitions will be resized as required.
 336 .sp
 337 The partition
 338 .I type
 339 is given in hex for MBR (DOS), without the 0x prefix, a GUID string for GPT, or
 340 a shortcut:
 341 .RS
 342 .TP
 343 .B L
 344 Linux; means 83 for MBR and 0FC63DAF-8483-4772-8E79-3D69D8477DE4 for GPT.
 345 .TP
 346 .B S
 347 swap area; means 82 for MBR and 0657FD6D-A4AB-43C4-84E5-0933C84B4F4F for GPT
 348 .TP
 349 .B E
 350 extended partition; means 5 for MBR
 351 .TP
 352 .B H
 353 home partition; means 933AC7E1-2EB4-4F13-B844-0E14E2AEF915 for GPT
 354 .TP
 355 .B X
 356 linux extended partition; means 85 for MBR.
 357 .TP
 358 .B U
 359 EFI System partition, means EF for MBR and C12A7328-F81F-11D2-BA4B-00A0C93EC93B for GPT
 360 .RE
 361 .PP
 362 The default
 363 .I type
 364 value is
 365 .I L
 366
 367 .I bootable
 368 is specified as [\fB*\fR|\fB-\fR], with as default not-bootable.  The
 369 value of this field is irrelevant for Linux - when Linux runs it has
 370 been booted already - but ir might play a role for certain boot
 371 loaders and for other operating systems.
 372 .RE
 373
 374 .B Named-fields format
 375 .RS
 376 This format is more readable, robust, extensible and allows to specify additional
 377 information (e.g. a UUID).  It is recommended to use this format to keep your scripts
 378 more readable.
 379 .RS
 380 .sp
 381 .RI [ "device \fB:" ] " name" [\fB= value "], ..."
 382 .sp
 383 .RE
 384 The
 385 .I device
 386 field is optional.  \fBsfdisk\fR extracts the partition number from the
 387 device name.  It allows to specify the partitions in random order.
 388 This functionality is mostly used by \fB\-\-dump\fR.
 389 Don't use it if you are not sure.
 390
 391 The
 392 .I value
 393 can be between quotation marks (e.g. name="This is partition name").
 394 The currently supported fields are:
 395 .RS
 396 .TP
 397 .BI start= number
 398 The first non-assigned sector aligned according to device I/O limits.  The default
 399 start offset for the first partition is 1 MiB. The offset may be followed by
 400 the multiplicative suffixes (KiB, MiB, GiB, TiB, PiB, EiB, ZiB and YiB) then
 401 the number is interpreted as offset in bytes.
 402 .TP
 403 .BI size= number
 404 Specify the partition size in sectors.  The number may be followed by the multiplicative
 405 suffixes (KiB, MiB, GiB, TiB, PiB, EiB, ZiB and YiB), then it's interpreted as size
 406 in bytes and the size is aligned according to device I/O limits.
 407 .TP
 408 .B bootable
 409 Mark the partition as bootable.
 410 .TP
 411 .BI attrs= string
 412 Partition attributes, usually GPT partition attribute bits.  See
 413 \fB\-\-part\-attrs\fR for more details about the GPT-bits string format.
 414 .TP
 415 .BI uuid= string
 416 GPT partition UUID.
 417 .TP
 418 .BI name= string
 419 GPT partition name.
 420 .TP
 421 .BI type= code
 422 A hexadecimal number (without 0x) for an MBR partition, or a GUID for a GPT partition.
 423 For backward compatibility the \fBId=\fR field has the same meaning.
 424 .RE
 425 .RE
 426
 427 .SH "EMPTY DISK LABEL"
 428 .B sfdisk
 429 does not create partition table without partitions by default. The lines with
 430 partitions are expected in the script by default. The empty partition table has
 431 to be explicitly requested by "label: <name>" script header line without any
 432 partitions lines. For example:
 433 .RS
 434 .sp
 435 .B "echo 'label: gpt' | sfdisk /dev/sdb"
 436 .sp
 437 .RE
 438 creates empty GPT partition table. Note that the \fB\-\-append\fR disables this feature.
 439
 440 .SH "BACKING UP THE PARTITION TABLE"
 441 It is recommended to save the layout of your devices.
 442 .B sfdisk
 443 supports two ways.
 444 .sp
 445 Use the \fB\-\-dump\fR option to save a description of the device layout
 446 to a text file.  The dump format is suitable for later \fBsfdisk\fR input.
 447 For example:
 448 .RS
 449 .sp
 450 .B "sfdisk --dump /dev/sda > sda.dump"
 451 .sp
 452 .RE
 453 This can later be restored by:
 454 .RS
 455 .sp
 456 .B "sfdisk /dev/sda < sda.dump"
 457 .RE
 458
 459 If you want to do a full (binary) backup of all sectors where the
 460 partition table is stored,
 461 then use the \fB\-\-backup\fR option.  It writes the sectors to
 462 ~/sfdisk-<device>-<offset>.bak files.  The default name of the backup file can
 463 be changed with the \fB\-\-backup\-file\fR option.  The backup files
 464 contain only raw data from the \fIdevice\fR.
 465 Note that the same concept of backup files is used by
 466 .BR wipefs (8).
 467 For example:
 468 .RS
 469 .sp
 470 .B "sfdisk --backup /dev/sda"
 471 .sp
 472 .RE
 473 The GPT header can later be restored by:
 474 .RS
 475 .sp
 476 .nf
 477 .B "dd  if=~/sfdisk-sda-0x00000200.bak  of=/dev/sda  \e"
 478 .B "  seek=$((0x00000200))  bs=1  conv=notrunc"
 479 .fi
 480 .sp
 481 .RE
 482 Note that \fBsfdisk\fR since version 2.26 no longer provides the \fB\-I\fR option to
 483 restore sectors.
 484 .BR dd (1)
 485 provides all necessary functionality.
 486
 487 .SH COLORS
 488 Implicit coloring can be disabled by an empty file \fI/etc/terminal-colors.d/sfdisk.disable\fR.
 489
 490 See
 491 .BR terminal-colors.d (5)
 492 for more details about colorization configuration. The logical color names
 493 supported by
 494 .B sfdisk
 495 are:
 496 .TP
 497 .B header
 498 The header of the output tables.
 499 .TP
 500 .B warn
 501 The warning messages.
 502 .TP
 503 .B welcome
 504 The welcome message.
 505
 506 .SH NOTES
 507 Since version 2.26 \fBsfdisk\fR no longer provides the \fB\-R\fR or
 508 \fB\-\-re\-read\fR option to force the kernel to reread the partition table.
 509 Use \fBblockdev \-\-rereadpt\fR instead.
 510 .PP
 511 Since version 2.26 \fBsfdisk\fR does not provide the \fB\-\-DOS\fR, \fB\-\-IBM\fR, \fB\-\-DOS\-extended\fR,
 512 \fB\-\-unhide\fR, \fB\-\-show\-extended\fR, \fB\-\-cylinders\fR, \fB\-\-heads\fR, \fB\-\-sectors\fR,
 513 \fB\-\-inside\-outer\fR, \fB\-\-not\-inside\-outer\fR options.
 514
 515 .SH ENVIRONMENT
 516 .IP SFDISK_DEBUG=all
 517 enables sfdisk debug output.
 518 .IP LIBFDISK_DEBUG=all
 519 enables libfdisk debug output.
 520 .IP LIBBLKID_DEBUG=all
 521 enables libblkid debug output.
 522 .IP LIBSMARTCOLS_DEBUG=all
 523 enables libsmartcols debug output.
 524
 525 .SH "SEE ALSO"
 526 .BR fdisk (8),
 527 .BR cfdisk (8),
 528 .BR parted (8),
 529 .BR partprobe (8),
 530 .BR partx (8)
 531
 532 .SH AUTHOR
 533 Karel Zak <kzak@redhat.com>
 534 .PP
 535 The current sfdisk implementation is based on the original sfdisk
 536 from Andries E. Brouwer.
 537
 538 .SH AVAILABILITY
 539 The sfdisk command is part of the util-linux package and is available from
 540 https://www.kernel.org/pub/linux/utils/util-linux/.