sfdisk(8) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | COMMANDS | OPTIONS | INPUT FORMATS | EMPTY DISK LABEL | BACKING UP THE PARTITION TABLE | COLORS | ENVIRONMENT | NOTES | AUTHORS | SEE ALSO | AVAILABILITY | COLOPHON

SFDISK(8)                 System Administration                SFDISK(8)

NAME         top

       sfdisk - display or manipulate a disk partition table

SYNOPSIS         top

       sfdisk [options] device [-N partition-number]

       sfdisk [options] command

DESCRIPTION         top

       sfdisk is a script-oriented tool for partitioning any block
       device.  It runs in interactive mode if executed on a terminal
       (stdin refers to a terminal).

       Since version 2.26 sfdisk supports MBR (DOS), GPT, SUN and SGI
       disk labels, but no longer provides any functionality for CHS
       (Cylinder-Head-Sector) addressing.  CHS has never been important
       for Linux, and this addressing concept does not make any sense
       for new devices.

       sfdisk protects the first disk sector when create a new disk
       label.  The option --wipe always disables this protection.  Note
       that fdisk(8) and cfdisk(8) completely erase this area by
       default.

       sfdisk (since version 2.26) aligns the start and end of
       partitions to block-device I/O limits when relative sizes are
       specified, when the default values are used or when
       multiplicative suffixes (e.g., MiB) are used for sizes.  It is
       possible that partition size will be optimized (reduced or
       enlarged) due to alignment if the start offset is specified
       exactly in sectors and partition size relative or by
       multiplicative suffixes.

       The recommended way is not to specify start offsets at all and
       specify partition size in MiB, GiB (or so).  In this case sfdisk
       aligns all partitions to block-device I/O limits (or when I/O
       limits are too small then to megabyte boundary to keep disk
       layout portable).  If this default behaviour is unwanted (usually
       for very small partitions) then specify offsets and sizes in
       sectors.  In this case sfdisk entirely follows specified numbers
       without any optimization.

       sfdisk does not create the standard system partitions for SGI and
       SUN disk labels like fdisk(8) does.  It is necessary to
       explicitly create all partitions including whole-disk system
       partitions.

       sfdisk uses BLKRRPART (reread partition table) ioctl to make sure
       that the device is not used by system or other tools (see also
       --no-reread).  It's possible that this feature or another sfdisk
       activity races with udevd.  The recommended way how to avoid
       possible collisions is to use --lock option.  The exclusive lock
       will cause udevd to skip the event handling on the device.

       The sfdisk prompt is only a hint for users and a displayed
       partition number does not mean that the same partition table
       entry will be created (if -N not specified), especially for
       tables with gaps.

COMMANDS         top

       The commands are mutually exclusive.

       [-N partition-number] device
              The default sfdisk command is to read the specification
              for the desired partitioning of device from standard
              input, and then create a partition table according to the
              specification.  See below for the description of the input
              format.  If standard input is a terminal, then sfdisk
              starts an interactive session.

              If the option -N is specified, then the changes are
              applied to the partition addressed by partition-number.
              The unspecified fields of the partition are not modified.

              Note that it's possible to address an unused partition
              with -N.  For example, an MBR always contains 4
              partitions, but the number of used partitions may be
              smaller.  In this case sfdisk follows the default values
              from the partition table and does not use built-in
              defaults for the unused partition given with -N.  See also
              --append.

       -A, --activate device [partition-number...]
              Switch on the bootable flag for the specified partitions
              and switch off the bootable flag on all unspecified
              partitions. The special placeholder '-' may be used
              instead of the partition numbers to switch off the
              bootable flag on all partitions.

              The activation command is supported for MBR and PMBR only.
              If a GPT label is detected, then sfdisk prints warning and
              automatically enters PMBR.

              If no partition-number is specified, then list the
              partitions with an enabled flag.

       --delete device [partition-number...]
              Delete all or the specified partitions.

       -d, --dump device
              Dump the partitions of a device in a format that is usable
              as input to sfdisk.  See the section BACKING UP THE
              PARTITION TABLE.

       -g, --show-geometry [device...]
              List the geometry of all or the specified devices. For
              backward compatibility the deprecated option
              --show-pt-geometry have the same meaning as this one.

       -J, --json device
              Dump the partitions of a device in JSON format.  Note that
              sfdisk is not able to use JSON as input format.

       -l, --list [device...]
              List the partitions of all or the specified devices.  This
              command can be used together with --verify.

       -F, --list-free [device...]
              List the free unpartitioned areas on all or the specified
              devices.

       --part-attrs device partition-number [attributes]
              Change the GPT partition attribute bits.  If attributes is
              not specified, then print the current partition settings.
              The attributes argument is a comma- or space-delimited
              list of bits numbers or bit names.  For example, the
              string "RequiredPartition,50,51" sets three bits.  The
              currently supported attribute bits are:

              Bit 0 (RequiredPartition)
                     If this bit is set, the partition is required for
                     the platform to function. The creator of the
                     partition indicates that deletion or modification
                     of the contents can result in loss of platform
                     features or failure for the platform to boot or
                     operate. The system cannot function normally if
                     this partition is removed, and it should be
                     considered part of the hardware of the system.

              Bit 1 (NoBlockIOProtocol)
                     EFI firmware should ignore the content of the
                     partition and not try to read from it.

              Bit 2 (LegacyBIOSBootable)
                     The partition may be bootable by legacy BIOS
                     firmware.

              Bits 3-47
                     Undefined and must be zero. Reserved for expansion
                     by future versions of the UEFI specification.

              Bits 48-63
                     Reserved for GUID specific use. The use of these
                     bits will vary depending on the partition type.
                     For example Microsoft uses bit 60 to indicate read-
                     only, 61 for shadow copy of another partition, 62
                     for hidden partitions and 63 to disable automount.

       --part-label device partition-number [label]
              Change the GPT partition name (label).  If label is not
              specified, then print the current partition label.

       --part-type device partition-number [type]
              Change the partition type.  If type is not specified, then
              print the current partition type.

              The type argument is hexadecimal for MBR, GUID for GPT,
              type alias (e.g. "linux") or type shortcut (e.g. 'L').
              For backward compatibility the options -c and --id have
              the same meaning as this one.

       --part-uuid device partition-number [uuid]
              Change the GPT partition UUID.  If uuid is not specified,
              then print the current partition UUID.

       --disk-id device [id]
              Change the disk identifier.  If id is not specified, then
              print the current identifier.  The identifier is UUID for
              GPT or unsigned integer for MBR.

       -r, --reorder device
              Renumber the partitions, ordering them by their start
              offset.

       -s, --show-size [device...]
              List the sizes of all or the specified devices in units of
              1024 byte size.  This command is DEPRECATED in favour of
              blockdev(8).

       -T, --list-types
              Print all supported types for the current disk label or
              the label specified by --label.

       -V, --verify [device...]
              Test whether the partition table and partitions seem
              correct.

       --relocate oper device
              Relocate partition table header. This command is currently
              supported for GPT header only.  The argument oper can be:

              gpt-bak-std
                     Move GPT backup header to the standard location at
                     the end of the device.

              gpt-bak-mini
                     Move GPT backup header behind the last partition.
                     Note that UEFI standard requires the backup header
                     at the end of the device and partitioning tools can
                     automatically relocate the header to follow the
                     standard.

OPTIONS         top

       -a, --append
              Don't create a new partition table, but only append the
              specified partitions.

              Note that unused partition maybe be re-used in this case
              although it is not the last partition in the partition
              table. See also -N to specify entry in the partition
              table.

       -b, --backup
              Back up the current partition table sectors before
              starting the partitioning.  The default backup file name
              is ~/sfdisk-<device>-<offset>.bak; to use another name see
              option -O, --backup-file.

       --color[=when]
              Colorize the output.  The optional argument when can be
              auto, never or always.  If the when argument is omitted,
              it defaults to auto.  The colors can be disabled; for the
              current built-in default see the --help output.  See also
              the COLORS section.

       -f, --force
              Disable all consistency checking.

       --Linux
              Deprecated and ignored option.  Partitioning that is
              compatible with Linux (and other modern operating systems)
              is the default.

       --lock[=mode]
              Use exclusive BSD lock for device or file it operates.
              The optional argument mode can be yes, no (or 1 and 0) or
              nonblock.  If the mode argument is omitted, it defaults to
              "yes".  This option overwrites environment variable
              $LOCK_BLOCK_DEVICE.  The default is not to use any lock at
              all, but it's recommended to avoid collisions with udevd
              or other tools.

       -n, --no-act
              Do everything except writing to the device.

       --no-reread
              Do not check through the re-read-partition-table ioctl
              whether the device is in use.

       --no-tell-kernel
              Don't tell the kernel about partition changes. This option
              is recommended together with --no-reread to modify a
              partition on used disk. The modified partition should not
              be used (e.g., mounted).

       -O, --backup-file path
              Override the default backup file name.  Note that the
              device name and offset are always appended to the file
              name.

       --move-data[=path]
              Move data after partition relocation, for example when
              moving the beginning of a partition to another place on
              the disk.  The size of the partition has to remain the
              same, the new and old location may overlap.  This option
              requires option -N in order to be processed on one
              specific partition only.

              The optional path specifies log file name. The log file
              contains information about all read/write operations on
              the partition data. The word "@default" as a path forces
              sfdisk to use ~/sfdisk-<devname>.move for the log.  The
              log is optional since v2.35.

              Note that this operation is risky and not atomic. Don't
              forget to backup your data!

              See also --move-use-fsync.

              In the example below, the first command creates a 100MiB
              free area before the first partition and moves the data it
              contains (e.g., a filesystem), the next command creates a
              new partition from the free space (at offset 2048), and
              the last command reorders partitions to match disk order
              (the original sdc1 will become sdc2).

              echo '+100M,' | sfdisk --move-data /dev/sdc -N 1
              echo '2048,' | sfdisk /dev/sdc --append
              sfdisk /dev/sdc --reorder

       --move-use-fsync
              Use the fsync(2) system call after each write when moving
              data to a new location by --move-data.

       -o, --output list
              Specify which output columns to print.  Use --help to get
              a list of all supported columns.

              The default list of columns may be extended if list is
              specified in the format +list (e.g., -o +UUID).

       -q, --quiet
              Suppress extra info messages.

       -u, --unit S
              Deprecated option.  Only the sector unit is supported.
              This option is not supported when using the --show-size
              command.

       -X, --label type
              Specify the disk label type (e.g., dos, gpt, ...).  If
              this option is not given, then sfdisk defaults to the
              existing label, but if there is no label on the device
              yet, then the type defaults to dos. The default or the
              current label may be overwritten by the "label: <name>"
              script header line. The option --label does not force
              sfdisk to create empty disk label (see the EMPTY DISK
              LABEL section below).

       -Y, --label-nested type
              Force editing of a nested disk label.  The primary disk
              label has to exist already.  This option allows editing
              for example a hybrid/protective MBR on devices with GPT.

       -w, --wipe when
              Wipe filesystem, RAID and partition-table signatures from
              the device, in order to avoid possible collisions.  The
              argument when can be auto, never or always.  When this
              option is not given, the default is auto, in which case
              signatures are wiped only when in interactive mode; except
              the old partition-table signatures which are always wiped
              before create a new partition-table if the argument when
              is not never.  The auto mode also does not wipe the first
              sector (boot sector), it is necessary to use the always
              mode to wipe this area.  In all cases detected signatures
              are reported by warning messages before a new partition
              table is created.  See also the wipefs(8) command.

       -W, --wipe-partitions when
              Wipe filesystem, RAID and partition-table signatures from
              a newly created partitions, in order to avoid possible
              collisions.  The argument when can be auto, never or
              always.  When this option is not given, the default is
              auto, in which case signatures are wiped only when in
              interactive mode and after confirmation by user.  In all
              cases detected signatures are reported by warning messages
              after a new partition is created.  See also wipefs(8)
              command.

       -v, --version
              Display version information and exit.

       -h, --help
              Display help text and exit.

INPUT FORMATS         top

       sfdisk supports two input formats and generic header lines.

   Header lines
       The optional header lines specify generic information that apply
       to the partition table.  The header-line format is:

       <name>: <value>

       The currently recognized headers are:

       unit   Specify the partitioning unit.  The only supported unit is
              sectors.

       label  Specify the partition table type.  For example dos or gpt.

       label-id
              Specify the partition table identifier.  It should be a
              hexadecimal number (with a 0x prefix) for MBR and a UUID
              for GPT.

       first-lba
              Specify the first usable sector for GPT partitions.

       last-lba
              Specify the last usable sector for GPT partitions.

       table-length
              Specify the maximal number of GPT partitions.

       grain  Specify minimal size in bytes used to calculate partitions
              alignment.  The default is 1MiB and it's strongly
              recommended to use the default.  Do not modify this
              variable if you're not sure.

       sector-size
              Specify sector size. This header is informative only and
              it is not used when sfdisk creates a new partition table,
              in this case the real device specific value is always used
              and sector size from the dump is ignored.

       Note that it is only possible to use header lines before the
       first partition is specified in the input.

   Unnamed-fields format

              start size type bootable

       where each line fills one partition descriptor.

       Fields are separated by whitespace, comma or semicolon possibly
       followed by whitespace; initial and trailing whitespace is
       ignored.  Numbers can be octal, decimal or hexadecimal; decimal
       is the default.  When a field is absent, empty or specified as
       '-' a default value is used.  But when the -N option (change a
       single partition) is given, the default for each field is its
       previous value.

       The default value of start is the first non-assigned sector
       aligned according to device I/O limits.  The default start offset
       for the first partition is 1 MiB.  The offset may be followed by
       the multiplicative suffixes (KiB, MiB, GiB, TiB, PiB, EiB, ZiB
       and YiB) then the number is interpreted as offset in bytes.

       The default value of size indicates "as much as possible"; i.e.,
       until the next partition or end-of-device.  A numerical argument
       is by default interpreted as a number of sectors, however if the
       size is followed by one of the multiplicative suffixes (KiB, MiB,
       GiB, TiB, PiB, EiB, ZiB and YiB) then the number is interpreted
       as the size of the partition in bytes and it is then aligned
       according to the device I/O limits.  A '+' can be used instead of
       a number to enlarge the partition as much as possible.  Note '+'
       is equivalent to the default behaviour for a new partition;
       existing partitions will be resized as required.

       The partition type is given in hex for MBR (DOS) where 0x prefix
       is optional; a GUID string for GPT; a shortcut or an alias. It's
       recommended to use two letters for MBR hex codes to avoid
       collision between deprecated shortcut 'E' and '0E' MBR hex code.
       For backward compatibility sfdisk tries to interpret type as a
       shortcut as a first possibility in partitioning scripts although
       on other places (e.g.  --part-type command) it tries shortcuts as
       the last possibility.

       Since v2.36 libfdisk supports partition type aliases as extension
       to shortcuts. The alias is a simple human readable word (e.g.
       "linux").

       Since v2.37 libfdisk supports partition type names on input,
       ignoring the case of the characters and all non-alphanumeric and
       non-digit characters in the name (e.g. "Linux /usr x86" is the
       same as "linux usr-x86").

       Supported shortcuts and aliases:

       L - alias 'linux'
              Linux; means 83 for MBR and
              0FC63DAF-8483-4772-8E79-3D69D8477DE4 for GPT.

       S - alias 'swap'
              swap area; means 82 for MBR and 0657FD6D-
              A4AB-43C4-84E5-0933C84B4F4F for GPT

       Ex - alias 'extended'
              MBR extended partition; means 05 for MBR.  The original
              shortcut 'E' is deprecated due to collision with 0x0E MBR
              partition type.

       H - alias 'home'
              home partition; means 933AC7E1-2EB4-4F13-B844-0E14E2AEF915
              for GPT

       U - alias 'uefi'
              EFI System partition, means EF for MBR and
              C12A7328-F81F-11D2-BA4B-00A0C93EC93B for GPT

       R - alias 'raid'
              Linux RAID; means FD for MBR and A19D880F-05FC-4D3B-
              A006-743F0F84911E for GPT

       V - alias 'lvm'
              LVM; means 8E for MBR and
              E6D6D379-F507-44C2-A23C-238F2A3DF928 for GPT

       The default type value is linux

       The shortcut 'X' for Linux extended partition (85) is deprecated
       in favour of 'Ex'.

       bootable is specified as [*|-], with as default not-bootable.
       The value of this field is irrelevant for Linux - when Linux runs
       it has been booted already - but it might play a role for certain
       boot loaders and for other operating systems.

   Named-fields format
       This format is more readable, robust, extensible and allows
       specifying additional information (e.g., a UUID).  It is
       recommended to use this format to keep your scripts more
       readable.

              [device :] name[=value], ...

       The device field is optional.  sfdisk extracts the partition
       number from the device name.  It allows specifying the partitions
       in random order.  This functionality is mostly used by --dump.
       Don't use it if you are not sure.

       The value can be between quotation marks (e.g., name="This is
       partition name").  The currently supported fields are:

       start=number
              The first non-assigned sector aligned according to device
              I/O limits.  The default start offset for the first
              partition is 1 MiB. The offset may be followed by the
              multiplicative suffixes (KiB, MiB, GiB, TiB, PiB, EiB, ZiB
              and YiB) then the number is interpreted as offset in
              bytes.

       size=number
              Specify the partition size in sectors.  The number may be
              followed by the multiplicative suffixes (KiB, MiB, GiB,
              TiB, PiB, EiB, ZiB and YiB), then it's interpreted as size
              in bytes and the size is aligned according to device I/O
              limits.

       bootable
              Mark the partition as bootable.

       attrs=string
              Partition attributes, usually GPT partition attribute
              bits.  See --part-attrs for more details about the GPT-
              bits string format.

       uuid=string
              GPT partition UUID.

       name=string
              GPT partition name.

       type=code
              A hexadecimal number (without 0x) for an MBR partition, a
              GUID for a GPT partition, a shortcut as for unnamed-fields
              format or a type name (e.g. type="Linux /usr (x86)").  See
              above the section about the unnamed-fields format for more
              details.  For backward compatibility the Id= field has the
              same meaning.

EMPTY DISK LABEL         top

       sfdisk does not create partition table without partitions by
       default. The lines with partitions are expected in the script by
       default. The empty partition table has to be explicitly requested
       by "label: <name>" script header line without any partitions
       lines. For example:

              echo 'label: gpt' | sfdisk /dev/sdb

       creates empty GPT partition table. Note that the --append
       disables this feature.

BACKING UP THE PARTITION TABLE         top

       It is recommended to save the layout of your devices.  sfdisk
       supports two ways.

       Use the --dump option to save a description of the device layout
       to a text file.  The dump format is suitable for later sfdisk
       input.  For example:

              sfdisk --dump /dev/sda > sda.dump

       This can later be restored by:

              sfdisk /dev/sda < sda.dump

       If you want to do a full (binary) backup of all sectors where the
       partition table is stored, then use the --backup option.  It
       writes the sectors to ~/sfdisk-<device>-<offset>.bak files.  The
       default name of the backup file can be changed with the
       --backup-file option.  The backup files contain only raw data
       from the device.  Note that the same concept of backup files is
       used by wipefs(8).  For example:

              sfdisk --backup /dev/sda

       The GPT header can later be restored by:

              dd  if=~/sfdisk-sda-0x00000200.bak  of=/dev/sda  \
                seek=$((0x00000200))  bs=1  conv=notrunc

       Note that sfdisk since version 2.26 no longer provides the -I
       option to restore sectors.  dd(1) provides all necessary
       functionality.

COLORS         top

       Implicit coloring can be disabled by an empty file /etc/terminal-
       colors.d/sfdisk.disable.

       See terminal-colors.d(5) for more details about colorization
       configuration. The logical color names supported by sfdisk are:

       header The header of the output tables.

       warn   The warning messages.

       welcome
              The welcome message.

ENVIRONMENT         top

       SFDISK_DEBUG=all
              enables sfdisk debug output.

       LIBFDISK_DEBUG=all
              enables libfdisk debug output.

       LIBBLKID_DEBUG=all
              enables libblkid debug output.

       LIBSMARTCOLS_DEBUG=all
              enables libsmartcols debug output.

       LOCK_BLOCK_DEVICE=<mode>
              use exclusive BSD lock.  The mode is "1" or "0".  See
              --lock for more details.

NOTES         top

       Since version 2.26 sfdisk no longer provides the -R or --re-read
       option to force the kernel to reread the partition table.  Use
       blockdev --rereadpt instead.

       Since version 2.26 sfdisk does not provide the --DOS, --IBM,
       --DOS-extended, --unhide, --show-extended, --cylinders, --heads,
       --sectors, --inside-outer, --not-inside-outer options.

AUTHORS         top

       Karel Zak <kzak@redhat.com>

       The current sfdisk implementation is based on the original sfdisk
       from Andries E. Brouwer.

SEE ALSO         top

       fdisk(8), cfdisk(8), parted(8), partprobe(8), partx(8)

AVAILABILITY         top

       The sfdisk command is part of the util-linux package and is
       available from
       https://www.kernel.org/pub/linux/utils/util-linux/.

COLOPHON         top

       This page is part of the util-linux (a random collection of Linux
       utilities) project.  Information about the project can be found
       at ⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩.  If you
       have a bug report for this manual page, send it to
       util-linux@vger.kernel.org.  This page was obtained from the
       project's upstream Git repository
       ⟨git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git⟩ on
       2021-03-21.  (At that time, the date of the most recent commit
       that was found in the repository was 2021-03-19.)  If you
       discover any rendering problems in this HTML version of the page,
       or you believe there is a better or more up-to-date source for
       the page, or you have corrections or improvements to the
       information in this COLOPHON (which is not part of the original
       manual page), send a mail to man-pages@man7.org

util-linux                      June 2015                      SFDISK(8)

Pages that refer to this page: repart.d(5)cfdisk(8)fdisk(8)