FDISK(8)		     System Administration		      FDISK(8)

NAME
       fdisk - manipulate disk partition table

SYNOPSIS
       fdisk [options] device

       fdisk -l [device...]

DESCRIPTION
       fdisk is a dialog-driven program for creation and manipulation of
       partition tables. It understands GPT, MBR, Sun, SGI and BSD partition
       tables.

       Block devices can be divided into one or more logical disks called
       partitions. This division is recorded in the partition table, usually
       found in sector 0 of the disk. (In the BSD world one talks about `disk
       slices' and a `disklabel'.)

       All partitioning is driven by device I/O limits (the topology) by
       default. fdisk is able to optimize the disk layout for a 4K-sector size
       and use an alignment offset on modern devices for MBR and GPT. It is
       always a good idea to follow fdisk's defaults as the default values
       (e.g., first and last partition sectors) and partition sizes specified
       by the +/-<size>{M,G,...} notation are always aligned according to the
       device properties.

       CHS (Cylinder-Head-Sector) addressing is deprecated and not used by
       default. Please, do not follow old articles and recommendations with
       fdisk -S <n> -H <n> advice for SSD or 4K-sector devices.

       Note that partx(8) provides a rich interface for scripts to print disk
       layouts, fdisk is mostly designed for humans. Backward compatibility in
       the output of fdisk is not guaranteed. The input (the commands) should
       always be backward compatible.

OPTIONS
       -b, --sector-size sectorsize
	   Specify the sector size of the disk. Valid values are 512, 1024,
	   2048, and 4096. The kernel is aware of the sector size for regular
	   block devices. Use this option only on very old kernels, when
	   working with disk images, or to override the kernel’s default
	   sector size. Since util-linux-2.17, fdisk distinguishes between
	   logical and physical sector size. This option changes both sector
	   sizes to the specified sectorsize.

       -B, --protect-boot
	   Don’t erase the beginning of the first disk sector when creating a
	   new disk label. This feature is supported for GPT and MBR.

       -c, --compatibility[=mode]
	   Specify the compatibility mode, 'dos' or 'nondos'. The default is
	   non-DOS mode. For backward compatibility, it is possible to use the
	   option without the mode argument — then the default is used. Note
	   that the optional mode argument cannot be separated from the -c
	   option by a space, the correct form is for example -c=dos.

       -L, --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.

       -l, --list
	   List the partition tables for the specified devices and then exit.

	   If no devices are given, the devices mentioned in /proc/partitions
	   (if this file exists) are used. Devices are always listed in the
	   order in which they are specified on the command-line, or by the
	   kernel listed in /proc/partitions.

       -x, --list-details
	   Like --list, but provides more details.

       --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
	   systemd-udevd(8) or other tools.

       -n, --noauto-pt
	   Don’t automatically create a default partition table on empty
	   device. The partition table has to be explicitly created by user
	   (by command like 'o', 'g', etc.).

       -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).

       -s, --getsz
	   Print the size in 512-byte sectors of each given block device. This
	   option is DEPRECATED in favour of blockdev(8).

       -t, --type type
	   Enable support only for disklabels of the specified type, and
	   disable support for all other types.

       -u, --units[=unit]
	   When listing partition tables, show sizes in 'sectors' or in
	   'cylinders'. The default is to show sizes in sectors. For backward
	   compatibility, it is possible to use the option without the unit
	   argument — then the default is used. Note that the optional unit
	   argument cannot be separated from the -u option by a space, the
	   correct form is for example '-u=cylinders'.

       -C, --cylinders number
	   Specify the number of cylinders of the disk. I have no idea why
	   anybody would want to do so.

       -H, --heads number
	   Specify the number of heads of the disk. (Not the physical number,
	   of course, but the number used for partition tables.) Reasonable
	   values are 255 and 16.

       -S, --sectors number
	   Specify the number of sectors per track of the disk. (Not the
	   physical number, of course, but the number used for partition
	   tables.) A reasonable value is 63.

       -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. In all cases detected signatures are reported by
	   warning messages before a new partition 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 signatures are wiped only
	   when in interactive mode and after confirmation by user. In all
	   cases detected signatures are reported by warning messages before a
	   new partition is created. See also wipefs(8) command.

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

       -V, --version
	   Display version and exit.

DEVICES
       The device is usually /dev/sda, /dev/sdb or so. A device name refers to
       the entire disk. Old systems without libata (a library used inside the
       Linux kernel to support ATA host controllers and devices) make a
       difference between IDE and SCSI disks. In such cases the device name
       will be /dev/hd* (IDE) or /dev/sd* (SCSI).

       The partition is a device name followed by a partition number. For
       example, /dev/sda1 is the first partition on the first hard disk in the
       system. See also Linux kernel documentation (the
       Documentation/admin-guide/devices.txt file).

SIZES
       The "last sector" dialog accepts partition size specified by number of
       sectors or by +/-<size>{K,B,M,G,...} notation.

       If the size is prefixed by '+' then it is interpreted as relative to
       the partition first sector. If the size is prefixed by '-' then it is
       interpreted as relative to the high limit (last available sector for
       the partition).

       In the case the size is specified in bytes, then the number may be
       followed by the multiplicative suffixes KiB (1024 bytes), MiB
       (1024*1024 bytes), and so on for GiB, TiB, PiB, EiB, ZiB and YiB. The
       "iB" is optional, e.g., "K" has the same meaning as "KiB".

       The relative sizes if specified with multiplicative suffixes (e.g.
       +100MiB) are always aligned according to device I/O limits. The
       +/-<size>{K,B,M,G,...} notation is recommended.

       The last sector of the partition is strictly calculated as <start> +
       <size> (without -1) if the size is specified by the +<sectors>
       notation. In this case, the size is not aligned to the device I/O
       limits.

       For backward compatibility fdisk also accepts the suffixes KB (1000
       bytes), MB (1000*1000 bytes), and so on for GB, TB, PB, EB, ZB and YB.
       These 10^N suffixes are deprecated.

SCRIPT FILES
       fdisk allows reading (by 'I' command) sfdisk(8) compatible script
       files. The script is applied to in-memory partition table, and then it
       is possible to modify the partition table before you write it to the
       device.

       And vice-versa it is possible to write the current in-memory disk
       layout to the script file by command 'O'.

       The script files are compatible between cfdisk(8), sfdisk(8), fdisk and
       other libfdisk applications. For more details see sfdisk(8).

DISK LABELS
       GPT (GUID Partition Table)
	   GPT is modern standard for the layout of the partition table. GPT
	   uses 64-bit logical block addresses, checksums, UUIDs and names for
	   partitions and an unlimited number of partitions (although the
	   number of partitions is usually restricted to 128 in many
	   partitioning tools).

	   Note that the first sector is still reserved for a protective MBR
	   in the GPT specification. It prevents MBR-only partitioning tools
	   from mis-recognizing and overwriting GPT disks.

	   GPT is always a better choice than MBR, especially on modern
	   hardware with a UEFI boot loader.

       DOS-type (MBR)
	   A DOS-type partition table can describe an unlimited number of
	   partitions. In sector 0 there is room for the description of 4
	   partitions (called `primary'). One of these may be an extended
	   partition; this is a box holding logical partitions, with
	   descriptors found in a linked list of sectors, each preceding the
	   corresponding logical partitions. The four primary partitions,
	   present or not, get numbers 1-4. Logical partitions are numbered
	   starting from 5.

	   In a DOS-type partition table the starting offset and the size of
	   each partition is stored in two ways: as an absolute number of
	   sectors (given in 32 bits), and as a Cylinders/Heads/Sectors triple
	   (given in 10+8+6 bits). The former is OK — with 512-byte sectors
	   this will work up to 2 TB. The latter has two problems. First,
	   these C/H/S fields can be filled only when the number of heads and
	   the number of sectors per track are known. And second, even if we
	   know what these numbers should be, the 24 bits that are available
	   do not suffice. DOS uses C/H/S only, Windows uses both, Linux never
	   uses C/H/S. The C/H/S addressing is deprecated and may be
	   unsupported in some later fdisk version.

	   Please, read the DOS-mode section if you want DOS-compatible
	   partitions. fdisk does not care about cylinder boundaries by
	   default.

       BSD/Sun-type
	   A BSD/Sun disklabel can describe 8 partitions, the third of which
	   should be a `whole disk' partition. Do not start a partition that
	   actually uses its first sector (like a swap partition) at cylinder
	   0, since that will destroy the disklabel. Note that a BSD label is
	   usually nested within a DOS partition.

       IRIX/SGI-type
	   An IRIX/SGI disklabel can describe 16 partitions, the eleventh of
	   which should be an entire `volume' partition, while the ninth
	   should be labeled `volume header'. The volume header will also
	   cover the partition table, i.e., it starts at block zero and
	   extends by default over five cylinders. The remaining space in the
	   volume header may be used by header directory entries. No
	   partitions may overlap with the volume header. Also do not change
	   its type or make some filesystem on it, since you will lose the
	   partition table. Use this type of label only when working with
	   Linux on IRIX/SGI machines or IRIX/SGI disks under Linux.

	   A sync(2) and an ioctl(BLKRRPART) (rereading the partition table
	   from disk) are performed before exiting when the partition table
	   has been updated.

DOS MODE AND DOS 6.X WARNING
       Note that all this is deprecated. You don’t have to care about things
       like geometry and cylinders on modern operating systems. If you really
       want DOS-compatible partitioning then you have to enable DOS mode and
       cylinder units by using the '-c=dos -u=cylinders' fdisk command-line
       options.

       The DOS 6.x FORMAT command looks for some information in the first
       sector of the data area of the partition, and treats this information
       as more reliable than the information in the partition table. DOS
       FORMAT expects DOS FDISK to clear the first 512 bytes of the data area
       of a partition whenever a size change occurs. DOS FORMAT will look at
       this extra information even if the /U flag is given — we consider this
       a bug in DOS FORMAT and DOS FDISK.

       The bottom line is that if you use fdisk or cfdisk(8) to change the
       size of a DOS partition table entry, then you must also use dd(1) to
       zero the first 512 bytes of that partition before using DOS FORMAT to
       format the partition. For example, if you were using fdisk to make a
       DOS partition table entry for /dev/sda1, then (after exiting fdisk and
       rebooting Linux so that the partition table information is valid) you
       would use the command dd if=/dev/zero of=/dev/sda1 bs=512 count=1 to
       zero the first 512 bytes of the partition.

       fdisk usually obtains the disk geometry automatically. This is not
       necessarily the physical disk geometry (indeed, modern disks do not
       really have anything like a physical geometry, certainly not something
       that can be described in the simplistic Cylinders/Heads/Sectors form),
       but it is the disk geometry that MS-DOS uses for the partition table.

       Usually all goes well by default, and there are no problems if Linux is
       the only system on the disk. However, if the disk has to be shared with
       other operating systems, it is often a good idea to let an fdisk from
       another operating system make at least one partition. When Linux boots
       it looks at the partition table, and tries to deduce what (fake)
       geometry is required for good cooperation with other systems.

       Whenever a partition table is printed out in DOS mode, a consistency
       check is performed on the partition table entries. This check verifies
       that the physical and logical start and end points are identical, and
       that each partition starts and ends on a cylinder boundary (except for
       the first partition).

       Some versions of MS-DOS create a first partition which does not begin
       on a cylinder boundary, but on sector 2 of the first cylinder.
       Partitions beginning in cylinder 1 cannot begin on a cylinder boundary,
       but this is unlikely to cause difficulty unless you have OS/2 on your
       machine.

       For best results, you should always use an OS-specific partition table
       program. For example, you should make DOS partitions with the DOS FDISK
       program and Linux partitions with the Linux fdisk or Linux cfdisk(8)
       programs.

COLORS
       The output colorization is implemented by terminal-colors.d(5)
       functionality.  Implicit coloring can be disabled by an empty file

	  /etc/terminal-colors.d/fdisk.disable

       for the fdisk command or for all tools by

	  /etc/terminal-colors.d/disable

       Since version 2.41, the $NO_COLOR environment variable is also
       supported to disable output colorization unless explicitly enabled by a
       command-line option.

       The user-specific $XDG_CONFIG_HOME/terminal-colors.d or
       $HOME/.config/terminal-colors.d overrides the global setting.

       Note that the output colorization may be enabled by default, and in
       this case terminal-colors.d directories do not have to exist yet.

       The logical color names supported by fdisk are:

       header
	   The header of the output tables.

       help-title
	   The help section titles.

       warn
	   The warning messages.

       welcome
	   The welcome message.

ENVIRONMENT
       FDISK_DEBUG=all
	   enables fdisk debug output.

       LIBFDISK_DEBUG=all
	   enables libfdisk debug output.

       LIBBLKID_DEBUG=all
	   enables libblkid debug output.

       LIBSMARTCOLS_DEBUG=all
	   enables libsmartcols debug output.

       LIBSMARTCOLS_DEBUG_PADDING=on
	   use visible padding characters.

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

AUTHORS
       Karel Zak <kzak@redhat.com>, Davidlohr Bueso <dave@gnu.org>

       The original version was written by Andries E. Brouwer, A. V. Le Blanc
       and others.

SEE ALSO
       cfdisk(8), mkfs(8), partx(8), sfdisk(8)

REPORTING BUGS
       For bug reports, use the issue tracker
       <https://github.com/util-linux/util-linux/issues>.

AVAILABILITY
       The fdisk 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/>.

util-linux 2.41.2		  2025-09-22			      FDISK(8)