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 | REPORTING BUGS | AVAILABILITY

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)

REPORTING BUGS         top

       For bug reports, use the issue tracker at
       https://github.com/karelzak/util-linux/issues.

AVAILABILITY         top

       The sfdisk command is part of the util-linux package which can be
       downloaded from Linux Kernel Archive
       <https://www.kernel.org/pub/linux/utils/util-linux/>. 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
       2021-08-27. (At that time, the date of the most recent commit
       that was found in the repository was 2021-08-24.) 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 2.37.109-b366e69    2021-06-20                      SFDISK(8)

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