Provided by: gdisk_1.0.5-1_amd64 bug


       sgdisk - Command-line GUID partition table (GPT) manipulator for Linux and Unix


       sgdisk [ options ] device


       GPT  fdisk  is  a text-mode menu-driven package for creation and manipulation of partition
       tables. It consists of two programs: the text-mode interactive gdisk and the  command-line
       sgdisk.  Either  program  will automatically convert an old-style Master Boot Record (MBR)
       partition table or BSD disklabel stored without an MBR  carrier  partition  to  the  newer
       Globally  Unique  Identifier  (GUID)  Partition  Table  (GPT)  format, or will load a GUID
       partition table. This man page documents the command-line sgdisk program.

       Some advanced data manipulation  and  recovery  options  require  you  to  understand  the
       distinctions  between the main and backup data, as well as between the GPT headers and the
       partition tables. For information  on  MBR  vs.  GPT,  as  well  as  GPT  terminology  and
       structure,  see  the  extended  gdisk  documentation at or
       consult Wikipedia.

       The sgdisk program employs a user interface that's based entirely  on  the  command  line,
       making  it  suitable  for  use  in scripts or by experts who want to make one or two quick
       changes to a disk. (The program may query the user when certain  errors  are  encountered,
       though.)  The  program's name is based on sfdisk, but the user options of the two programs
       are entirely different from one another.

       Ordinarily, sgdisk operates on disk device files,  such  as  /dev/sda  or  /dev/hda  under
       Linux,  /dev/disk0  under Mac OS X, or /dev/ad0 or /dev/da0 under FreeBSD. The program can
       also operate on disk image files, which can be either copies of whole disks (made with dd,
       for  instance) or raw disk images used by emulators such as QEMU or VMWare. Note that only
       raw disk images are supported; sgdisk cannot work on compressed  or  other  advanced  disk
       image formats.

       The  MBR  partitioning  system uses a combination of cylinder/head/sector (CHS) addressing
       and logical block addressing (LBA). The former is  klunky  and  limiting.  GPT  drops  CHS
       addressing  and uses 64-bit LBA mode exclusively. Thus, GPT data structures, and therefore
       sgdisk, do not need to deal with CHS geometries and all the problems they create.

       For best results, you should use an OS-specific partition table program whenever possible.
       For  example,  you  should make Mac OS X partitions with the Mac OS X Disk Utility program
       and Linux partitions with the Linux gdisk, sgdisk, or GNU Parted programs.

       Upon start, sgdisk attempts to identify the partition type in use on the disk. If it finds
       valid  GPT  data,  sgdisk will use it. If sgdisk finds a valid MBR or BSD disklabel but no
       GPT data, it will attempt to convert the MBR or disklabel into GPT form.  (BSD  disklabels
       are  likely  to  have unusable first and/or final partitions because they overlap with the
       GPT data structures, though.) GPT fdisk can identify, but not use data in, Apple Partition
       Map  (APM)  disks,  which are used on 680x0- and PowerPC-based Macintoshes. If you specify
       any option that results in changes to an  MBR  or  BSD  disklabel,  sgdisk  ignores  those
       changes  unless  the -g (--mbrtogpt), -z (--zap), or -Z (--zap-all) option is used. If you
       use the -g option, sgdisk replaces the MBR  or  disklabel  with  a  GPT.  This  action  is
       potentially  dangerous!  Your  system  may become unbootable, and partition type codes may
       become corrupted if the disk uses unrecognized type codes. Boot problems are  particularly
       likely if you're multi-booting with any GPT-unaware OS.

       The  MBR-to-GPT  conversion  will leave at least one gap in the partition numbering if the
       original MBR used logical partitions. These gaps are harmless, but you can eliminate  them
       by  using  the -s (--sort) option, if you like. (Doing this may require you to update your
       /etc/fstab file.)

       When creating a fresh partition table, certain considerations may be in order:

       *      For data (non-boot) disks, and for boot disks used  on  BIOS-based  computers  with
              GRUB  as  the  boot  loader,  partitions  may  be  created in whatever order and in
              whatever sizes are desired.

       *      Boot disks for EFI-based systems require an EFI System  Partition  (gdisk  internal
              code  0xEF00)  formatted  as  FAT-32.  I recommended making this partition 550 MiB.
              (Smaller ESPs are common, but some EFIs have flaky FAT drivers that  necessitate  a
              larger partition for reliable operation.) Boot-related files are stored here. (Note
              that GNU Parted identifies such partitions as having the "boot flag" set.)

       *      Some boot loaders for BIOS-based systems make use of a BIOS Boot  Partition  (gdisk
              internal  code  0xEF02),  in  which  the  secondary boot loader is stored, possibly
              without the benefit of a filesystem. (GRUB2 may optionally use such  a  partition.)
              This  partition can typically be quite small (roughly 32 to 200 KiB, although 1 MiB
              is more common in practice), but you should consult your boot loader  documentation
              for details.

       *      If  Windows  is  to  boot  from  a GPT disk, a partition of type Microsoft Reserved
              (sgdisk internal code 0x0C01) is recommended. This partition should  be  about  128
              MiB  in  size.  It  ordinarily  follows  the  EFI  System Partition and immediately
              precedes the Windows data  partitions.  (Note  that  GNU  Parted  creates  all  FAT
              partitions  as  this  type,  which actually makes the partition unusable for normal
              file storage in both Windows and Mac OS X.)

       *      Some OSes' GPT utilities create some blank space (typically  128  MiB)  after  each
              partition.  The  intent  is to enable future disk utilities to use this space. Such
              free space is not required of GPT disks, but creating it may help  in  future  disk


       Some  options  take no arguments, others take one argument (typically a partition number),
       and others take compound arguments with colon delimitation. For instance, -n (--new) takes
       a partition number, a starting sector number, and an ending sector number, as in sgdisk -n
       2:2000:50000 /dev/sdc, which creates a new partition, numbered 2, starting at sector  2000
       an ending at sector 50,000, on /dev/sdc.

       Unrelated  options may be combined; however, some such combinations will be nonsense (such
       as deleting a partition and then changing its GUID type code).  sgdisk interprets  options
       in  the  order  in  which  they're  entered,  so  effects can vary depending on order. For
       instance, sgdisk -s -d 2 sorts the partition table entries and then  deletes  partition  2
       from  the  newly-sorted list; but sgdisk -d 2 -s deletes the original partition 2 and then
       sorts the modified partition table.

       Error checking and opportunities to correct mistakes in sgdisk are minimal.  Although  the
       program  endeavors  to  keep  the  GPT  data  structures  legal,  it  does  not prompt for
       verification before performing its  actions.  Unless  you  require  a  command-line-driven
       program, you should use the interactive gdisk instead of sgdisk, since gdisk allows you to
       quit without saving your changes, should you make a mistake.

       Although sgdisk is  based  on  the  same  partition-manipulation  code  as  gdisk,  sgdisk
       implements fewer features than its interactive sibling. Options available in sgdisk are:

       -a, --set-alignment=value
              Set  the  sector  alignment  multiple.  GPT fdisk aligns the start of partitions to
              sectors that are multiples of this value, which defaults to 1 MiB  (2048  on  disks
              with  512-byte  sectors)  on  freshly  formatted  disks.  This  alignment  value is
              necessary to obtain optimum performance with Western Digital  Advanced  Format  and
              similar  drives  with larger physical than logical sector sizes, with some types of
              RAID arrays, and with SSD devices.

              View or set partition attributes. Use list to see defined (known) attribute values.
              Omit the partition number (and even the device filename) when  using  this  option.
              The  others  require  a partition number. The show and get options show the current
              attribute settings (all attributes or for a particular bit, respectively). The  or,
              nand, xor, =, set, clear, and toggle options enable you to change the attribute bit
              value. The set, clear, toggle, and get options work on a  bit  number;  the  others
              work on a hexadecimal bit mask. For example, type sgdisk -A 4:set:2 /dev/sdc to set
              the bit 2 attribute (legacy BIOS bootable) on partition 4 on /dev/sdc.

       -b, --backup=file
              Save partition data to a backup file.  You  can  back  up  your  current  in-memory
              partition  table  to  a disk file using this option. The resulting file is a binary
              file consisting of the protective MBR, the main GPT header, the backup GPT  header,
              and  one copy of the partition table, in that order. Note that the backup is of the
              current in-memory data structures, so if you launch the program, make changes,  and
              then  use  this  option,  the  backup  will  reflect  your changes. If the GPT data
              structures are damaged, the backup may not accurately reflect  the  damaged  state;
              instead, they will reflect GPT fdisk's first-pass interpretation of the GPT.

       -c, --change-name=partnum:name
              Change  the  GPT  name of a partition. This name is encoded as a UTF-16 string, but
              proper entry and display of anything beyond basic ASCII  values  requires  suitable
              locale  and  font support. For the most part, Linux ignores the partition name, but
              it may be important in some OSes. If you want to set a name that includes a  space,
              enclose  it in quotation marks, as in sgdisk -c 1:"Sample Name" /dev/sdb. Note that
              the GPT name of a partition is distinct from the filesystem name, which is  encoded
              in the filesystem's data structures.

       -C, --recompute-chs
              Recompute CHS values in protective or hybrid MBR. This option can sometimes help if
              a disk utility, OS, or BIOS doesn't like the CHS values used by the  partitions  in
              the  protective  or hybrid MBR. In particular, the GPT specification requires a CHS
              value of 0xFFFFFF for over-8GiB partitions, but this value is  technically  illegal
              by  the usual standards. Some BIOSes hang if they encounter this value. This option
              will recompute a more normal  CHS  value  --  0xFEFFFF  for  over-8GiB  partitions,
              enabling these BIOSes to boot.

       -d, --delete=partnum
              Delete a partition. This action deletes the entry from the partition table but does
              not disturb the data within the sectors originally allocated to  the  partition  on
              the  disk.  If  a  corresponding  hybrid MBR partition exists, gdisk deletes it, as
              well, and expands any adjacent 0xEE (EFI GPT) MBR protective partition to fill  the
              new free space.

       -D, --display-alignment
              Display  current sector alignment value. Partitions will be created on multiples of
              the sector value reported by this option. You can change the alignment  value  with
              the -a option.

       -e, --move-second-header
              Move  backup  GPT data structures to the end of the disk. Use this option if you've
              added disks to a RAID array, thus creating a virtual disk with space  that  follows
              the  backup  GPT data structures. This command moves the backup GPT data structures
              to the end of the disk, where they belong.

       -E, --end-of-largest
              Displays the sector number of the end of the largest available block of sectors  on
              the  disk. A script may store this value and pass it back as part of -n's option to
              create a partition. If no unallocated sectors are available, this function  returns
              the value 0.

       -f, --first-in-largest
              Displays  the  sector number of the start of the largest available block of sectors
              on the disk. A script may store this value and pass it back as part of -n's  option
              to  create  a  partition.  If  no  unallocated sectors are available, this function
              returns the value 0. Note that this parameter is blind to partition alignment; when
              you actually create a partition, its start point might be changed from this value.

       -F, --first-aligned-in-largest
              Similar  to  -f  (--first-in-largest),  except  returns  the sector number with the
              current alignment correction applied. Use this function if you need to compute  the
              actual  partition  start  point rather than a theoretical start point or the actual
              start point if you set the alignment value to 1.

       -g, --mbrtogpt
              Convert an MBR or BSD disklabel disk to a GPT disk. As a  safety  measure,  use  of
              this  option  is  required on MBR or BSD disklabel disks if you intend to save your
              changes, in order to prevent accidentally damaging such disks.

       -G, --randomize-guids
              Randomize the disk's GUID and all partitions' unique GUIDs (but not their partition
              type code GUIDs). This function may be used after cloning a disk in order to render
              all GUIDs once again unique.

       -h, --hybrid
              Create a hybrid MBR. This  option  takes  from  one  to  three  partition  numbers,
              separated  by  colons,  as  arguments. You may optionally specify a final partition
              "EE" to indicate that the EFI GPT (type 0xEE) should be placed last in  the  table,
              otherwise it will be placed first, followed by the partition(s) you specify.  Their
              type codes are based on the GPT fdisk  type  codes  divided  by  0x0100,  which  is
              usually  correct for Windows partitions. If the active/bootable flag should be set,
              you must do so in  another  program,  such  as  fdisk.  The  gdisk  program  offers
              additional hybrid MBR creation options.

       -i, --info=partnum
              Show  detailed  partition  information.  The summary information produced by the -p
              command necessarily omits many details, such as the partition's unique GUID and the
              translation  of  sgdisk's internal partition type code to a plain type name. The -i
              option displays this information for a single partition.

       -j, --adjust-main-table=sector
              Adjust the location of the main partition table. This value is normally 2,  but  it
              may  need  to  be  increased  in some cases, such as when a system-on-chip (SoC) is
              hard-coded to read boot code from sector 2.  I  recommend  against  adjusting  this
              value unless doing so is absolutely necessary.

       -l, --load-backup=file
              Load  partition  data  from  a  backup  file.  This option is the reverse of the -b
              option. Note that restoring partition data from anything but the original  disk  is
              not  recommended. This option will work even if the disk's original partition table
              is bad; however, most other options on the same command line will be ignored.

       -L, --list-types
              Display a summary of partition types. GPT uses a GUID to identify  partition  types
              for  particular  OSes and purposes. For ease of data entry, sgdisk compresses these
              into two-byte (four-digit hexadecimal) values that are related to their  equivalent
              MBR  codes.  Specifically,  the  MBR  code is multiplied by hexadecimal 0x0100. For
              instance, the code for Linux swap space in MBR is 0x82, and it's 0x8200 in gdisk. A
              one-to-one  correspondence  is  impossible, though. Most notably, the codes for all
              varieties of FAT and NTFS partition correspond to a single  GPT  code  (entered  as
              0x0700  in  sgdisk).  Some OSes use a single MBR code but employ many more codes in
              GPT. For these, sgdisk adds code numbers sequentially, such as 0xa500 for a FreeBSD
              disklabel,  0xa501  for FreeBSD boot, 0xa502 for FreeBSD swap, and so on. Note that
              these two-byte codes are unique to gdisk and sgdisk. This option does  not  require
              you to specify a valid disk device filename.

       -m, --gpttombr
              Convert  disk  from  GPT  to MBR form. This option takes from one to four partition
              numbers, separated by colons, as arguments. Their type codes are based on  the  GPT
              fdisk  type codes divided by 0x0100. If the active/bootable flag should be set, you
              must do so in another program, such as fdisk.  The gdisk program offers  additional
              MBR  conversion  options.  It  is not possible to convert more than four partitions
              from GPT to MBR form or to convert partitions that start above  the  2TiB  mark  or
              that are larger than 2TiB.

       -n, --new=partnum:start:end
              Create  a  new  partition.  You  enter  a partition number, starting sector, and an
              ending sector. Both start and end sectors can be specified  in  absolute  terms  as
              sector  numbers or as positions measured in kibibytes (K), mebibytes (M), gibibytes
              (G), tebibytes (T), or pebibytes (P); for instance, 40M specifies a position  40MiB
              from  the start of the disk. You can specify locations relative to the start or end
              of the specified default range by preceding the number by a '+' or '-'  symbol,  as
              in  +2G to specify a point 2GiB after the default start sector, or -200M to specify
              a point 200MiB before the last  available  sector.  A  start  or  end  value  of  0
              specifies  the default value, which is the start of the largest available block for
              the start sector and the end of the same block for the end sector. A partnum  value
              of  0  causes  the  program to use the first available partition number. Subsequent
              uses of the -A, -c, -t, and -u options  may  also  use  0  to  refer  to  the  same

       -N, --largest-new=num
              Create a new partition that fills the largest available block of space on the disk.
              You can use the -a (--set-alignment) option to adjust the alignment, if desired.  A
              num value of 0 causes the program to use the first available partition number.

       -o, --clear
              Clear  out  all  partition  data.  This  includes  GPT  header  data, all partition
              definitions, and the protective MBR. Note that this operation will, like most other
              operations,  fail  on  a damaged disk. If you want to prepare a disk you know to be
              damaged for GPT use, you should first  wipe  it  with  -Z  and  then  partition  it
              normally. This option will work even if the disk's original partition table is bad;
              however, most other options on the same command line will be ignored.

       -O, --print-mbr
              Display basic MBR partition summary data. This includes partition numbers, starting
              and  ending  sector  numbers,  partition  sizes,  MBR  partition  types  codes, and
              partition names. This option  is  useful  mainly  for  diagnosing  partition  table
              problems, particularly on disks with hybrid MBRs.

       -p, --print
              Display basic GPT partition summary data. This includes partition numbers, starting
              and ending sector numbers, partition sizes, sgdisk's  partition  types  codes,  and
              partition names. For additional information, use the -i (--info) option.

       -P, --pretend
              Pretend  to  make  specified  changes.  In-memory  GPT  data structures are altered
              according to other parameters, but changes are not written to disk.

       -r, --transpose
              Swap two partitions' entries in the partition table. One or both partitions may  be
              empty,  although  swapping  two  empty  partitions  is  pointless. For instance, if
              partitions 1-4 are defined, transposing 1 and 5 results in a table with  partitions
              numbered  from  2-5. Transposing partitions in this way has no effect on their disk
              space allocation; it only alters their order in the partition table.

       -R, --replicate=second_device_filename
              Replicate the main device's partition table on the specified second  device.   Note
              that  the  replicated partition table is an exact copy, including all GUIDs; if the
              device should have its own unique GUIDs, you should use the -G option  on  the  new

       -s, --sort
              Sort  partition  entries.  GPT  partition  numbers  need  not  match  the  order of
              partitions on the disk. If you want them to match, you can use this  option.   Note
              that  some  partitioning utilities sort partitions whenever they make changes. Such
              changes will be reflected in your  device  filenames,  so  you  may  need  to  edit
              /etc/fstab if you use this option.

       -t, --typecode=partnum:{hexcode|GUID}
              Change  a  single  partition's  type  code.  You enter the type code using either a
              two-byte hexadecimal number, as described earlier, or a fully-specified GUID value,
              such as EBD0A0A2-B9E5-4433-87C0-68B6B72699C7.

       -T, --transform-bsd=partnum
              Transform  BSD  partitions into GPT partitions. This option works on BSD disklabels
              held within GPT (or converted MBR) partitions. Converted partitions' type codes are
              likely  to  need  manual  adjustment. sgdisk will attempt to convert BSD disklabels
              stored on the main disk when launched, but this conversion  is  likely  to  produce
              first  and/or  last  partitions that are unusable. The many BSD variants means that
              the probability of sgdisk being unable to convert a BSD disklabel is high  compared
              to the likelihood of problems with an MBR conversion.

       -u, --partition-guid=partnum:guid
              Set  the  partition  unique  GUID  for  an  individual partition. The GUID may be a
              complete GUID or 'R' to set a random GUID.

       -U, --disk-guid=guid
              Set the GUID for the disk. The GUID may be a complete GUID or 'R' to set  a  random

              Print a brief summary of available options.

       -v, --verify
              Verify  disk.  This option checks for a variety of problems, such as incorrect CRCs
              and mismatched main and backup data. This option  does  not  automatically  correct
              most  problems,  though;  for  that,  you  must  use  options  on  the  recovery  &
              transformation menu. If no problems are found, this command displays a  summary  of
              unallocated disk space. This option will work even if the disk's original partition
              table is bad; however, most other options on the same command line will be ignored.

       -V, --version
              Display program version information. This option may be used without  specifying  a
              device filename.

       -z, --zap
              Zap (destroy) the GPT data structures and then exit. Use this option if you want to
              repartition a GPT disk using fdisk or some other GPT-unaware program.  This  option
              destroys  only  the  GPT  data  structures; it leaves the MBR intact. This makes it
              useful for wiping out GPT data structures after a disk has been  repartitioned  for
              MBR  using  a GPT-unaware utility; however, there's a risk that it will damage boot
              loaders or even the start of the first or end of the last MBR partition. If you use
              it  on  a valid GPT disk, the MBR will be left with an inappropriate EFI GPT (0xEE)
              partition definition, which you can delete using another utility.

       -Z, --zap-all
              Zap (destroy) the GPT and MBR data structures and then exit. This option works much
              like -z, but as it wipes the MBR as well as the GPT, it's more suitable if you want
              to repartition a disk after using this option, and completely unsuitable if  you've
              already repartitioned the disk.

       -?, --help
              Print a summary of options.


       sgdisk returns various values depending on its success or failure:

       0      Normal program execution

       1      Too few arguments

       2      An error occurred while reading the partition table

       3      Non-GPT disk detected and no -g option, but operation requires a write action

       4      An error prevented saving changes

       5      An error occurred while reading standard input (should never occur with sgdisk, but
              may with gdisk)

       8      Disk replication operation (-R) failed


       Known bugs and limitations include:

       *      The program compiles correctly only on Linux, FreeBSD, and Mac OS X. Linux versions
              for  x86-64 (64-bit), x86 (32-bit), and PowerPC (32-bit) have been tested, with the
              x86-64 version having seen the most testing.

       *      The FreeBSD version of the program can't write changes to the partition table to  a
              disk  when  existing  partitions on that disk are mounted. (The same problem exists
              with many other FreeBSD utilities, such as gpt, fdisk, and dd.) This limitation can
              be overcome by typing sysctl kern.geom.debugflags=16 at a shell prompt.

       *      The  fields  used to display the start and end sector numbers for partitions in the
              -p option are 14 characters wide. This translates to a limitation of about 45  PiB.
              On larger disks, the displayed columns will go out of alignment.

       *      The  program  can  load  only  up  to  128 partitions (4 primary partitions and 124
              logical partitions) when converting from MBR format. This limit can  be  raised  by
              changing  the  #define  MAX_MBR_PARTS  line  in the basicmbr.h source code file and
              recompiling; however,  such  a  change  will  require  using  a  larger-than-normal
              partition table. (The limit of 128 partitions was chosen because that number equals
              the 128 partitions supported by the most common partition table size.)

       *      Converting from MBR format sometimes fails because of  insufficient  space  at  the
              start  or  (more commonly) the end of the disk. Resizing the partition table (using
              the 's' option in the experts' menu) can sometimes overcome this problem;  however,
              in  extreme  cases  it may be necessary to resize a partition using GNU Parted or a
              similar tool prior to conversion with gdisk.

       *      MBR conversions work only if the disk has correct LBA partition descriptors.  These
              descriptors  should  be  present on any disk over 8 GiB in size or on smaller disks
              partitioned with any but very ancient software.

       *      BSD disklabel support can create first and/or last partitions that overlap with the
              GPT  data  structures. This can sometimes be compensated by adjusting the partition
              table size, but in extreme cases the affected partition(s) may need to be deleted.

       *      Because of the highly variable nature of BSD disklabel structures, conversions from
              this  form  may be unreliable -- partitions may be dropped, converted in a way that
              creates overlaps with other partitions, or converted with incorrect  start  or  end
              values. Use this feature with caution!

       *      Booting  after  converting  an MBR or BSD disklabel disk is likely to be disrupted.
              Sometimes re-installing a boot loader will fix the problem, but other times you may
              need  to  switch  boot  loaders.  Except on EFI-based platforms, Windows through at
              least Windows 7 RC doesn't support booting from GPT disks. Creating  a  hybrid  MBR
              (using  the  'h' option on the recovery & transformation menu) or abandoning GPT in
              favor of MBR may be your only options in this case.


       Primary author: Roderick W. Smith (


       * Yves Blusseau (

       * David Hubbard (

       * Justin Maggard (

       * Dwight Schauer (

       * Florian Zumbiehl (


       cfdisk(8), cgdisk(8), fdisk(8), gdisk(8), mkfs(8), parted(8), sfdisk(8), fixparts(8).


       The sgdisk command is part of the GPT fdisk package and is available from Rod Smith.