NAME
fdisk - manipulate disk partition tableSYNOPSIS
fdisk [options] deviceDESCRIPTION
fdisk is a dialog-driven program for creation and manipulation of partition tables. It understands GPT, MBR, Sun, SGI and BSD partition tables.OPTIONS
-b, --sector-size sectorsizeSpecify the sector size of the disk. Valid
values are 512, 1024, 2048, and 4096. (Recent kernels know the sector size.
Use this option only on old kernels or to override the kernel’s ideas.)
Since util-linux-2.17, fdisk differentiates between logical and
physical sector size. This option changes both sector sizes to
sectorsize.
Don’t erase the beginning of the first
disk sector when creating a new disk label. This feature is supported for GPT
and MBR.
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.
Display help text and exit.
Print version and exit.
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.
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.
Like --list, but provides more
details.
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.
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.).
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).
Print the size in 512-byte sectors of each
given block device. This option is DEPRECATED in favour of
blockdev(8).
Enable support only for disklabels of the
specified type, and disable support for all other types.
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'.
Specify the number of cylinders of the
disk. I have no idea why anybody would want to do so.
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.
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.
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.
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.
Display version information 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).SIZES
The "last sector" dialog accepts partition size specified by number of sectors or by +/-<size>{K,B,M,G,...} notation.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.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.
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.
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.
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.COLORS
The output colorization is implemented by terminal-colors.d(5) functionality. Implicit coloring can be disabled by an empty fileThe header of the output tables.
The help section titles.
The warning messages.
The welcome message.
ENVIRONMENT
FDISK_DEBUG=allenables fdisk debug output.
enables libfdisk debug output.
enables libblkid debug output.
enables libsmartcols debug output.
use visible padding characters.
use exclusive BSD lock. The mode is
"1" or "0". See --lock for more details.
AUTHORS
Karel <[email protected]>Zak Davidlohr <[email protected]>BuesoSEE ALSO
cfdisk(8), mkfs(8), partx(8), sfdisk(8)REPORTING BUGS
For bug reports, use the issue tracker at <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/>.2022-05-11 | util-linux 2.38.1 |