|
NAME | SYNOPSIS | DESCRIPTION | COMMANDS | OPTIONS | INPUT FORMATS | EMPTY DISK LABEL | BACKING UP THE PARTITION TABLE | COLORS | ENVIRONMENT | NOTES | AUTHORS | SEE ALSO | AVAILABILITY | COLOPHON |
|
|
|
SFDISK(8) System Administration SFDISK(8)
sfdisk - display or manipulate a disk partition table
sfdisk [options] device [-N partition-number]
sfdisk [options] command
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.
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.
-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.
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").
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, or a shortcut as for unnamed-
fields format. For backward compatibility the Id= field
has the same meaning.
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.
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.
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.
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.
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.
Karel Zak <kzak@redhat.com>
The current sfdisk implementation is based on the original sfdisk
from Andries E. Brouwer.
fdisk(8), cfdisk(8), parted(8), partprobe(8), partx(8)
The sfdisk command is part of the util-linux package and is
available from
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
2020-12-18. (At that time, the date of the most recent commit
that was found in the repository was 2020-12-17.) 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 June 2015 SFDISK(8)
Pages that refer to this page: repart.d(5), cfdisk(8), fdisk(8)
|
HTML rendering created 2020-12-21 by Michael Kerrisk, author of The Linux Programming Interface, maintainer of the Linux man-pages project. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|