sfdisk

SFDISK(8)                    System Administration                   SFDISK(8)

NAME
       sfdisk - display or manipulate a disk partition table

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

       sfdisk [options] command

DESCRIPTION
       sfdisk is a script-oriented tool for partitioning any block device.

       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 (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 align all par-
       titions 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.

COMMANDS
       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.  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  TA-
              BLE.

       -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  com-
              mand 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.
              The  currently  supported attribute bits are: RequiredPartition,
              NoBlockIOProtocol, LegacyBIOSBootable and GUID-specific bits  in
              the  range from 48 to 63.  For example, the string "RequiredPar-
              tition,50,51" sets three bits.

       --part-label device partition-number [label]
              Change the GPT partition name (label).  If label is  not  speci-
              fied, 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,  or  a  GUID  for GPT.  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.

       -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(1).

       -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.

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

       -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.

       -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 path overrides the default log file  name  (the  default  is
              ~/sfdisk-<devname>.move).   The  log  file  contains information
              about all read/write operations on the partition data.

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

              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

       -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  over-
              written  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 to edit 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. In all cases detected
              signatures are reported by warning messages before a new  parti-
              tion table is created.  See also 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  signa-
              tures  are wiped only when in interactive mode and after confir-
              mation 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
       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.

              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 off-
              set for the first partition is 1 MiB.  The offset  may  be  fol-
              lowed  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 inter-
              preted 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  possi-
              ble.   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), without the 0x
              prefix, a GUID string for GPT, or a shortcut:

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

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

                     E      extended partition; means 5 for MBR

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

                     X      linux extended partition; means 85 for MBR.

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

              The default type value is L

              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 ir 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  to
              specify 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 to specify the parti-
              tions 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 par-
                            tition, or a GUID for a GPT partition.  For  back-
                            ward  compatibility  the  Id=  field  has the same
                            meaning.

EMPTY DISK LABEL
       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
       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 par-
       tition 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
       Implicit  coloring  can be disabled by an empty file /etc/terminal-col-
       ors.d/sfdisk.disable.

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

       header The header of the output tables.

       warn   The warning messages.

       welcome
              The welcome message.

NOTES
       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, --sec-
       tors, --inside-outer, --not-inside-outer options.

ENVIRONMENT
       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.

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

AUTHOR
       Karel Zak <kzak@redhat.com>

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

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

util-linux                         June 2015                         SFDISK(8)
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