.\" sfdisk.8 -- man page for sfdisk
.\" Copyright (C) 2014 Karel Zak <kzak@redhat.com>
.\"
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.TH SFDISK 8 "September 2014" "util-linux" "System Administration"
.SH NAME
sfdisk \- display or manipulate a disk partition table
.SH SYNOPSIS
.B sfdisk
[options]
.I device
.RB [ \-N
.IR partition-number ]
.sp
.B sfdisk
[options]
.I command
.SH DESCRIPTION
.B sfdisk
is a script oriented tool for partitioning any block device.
Since version 2.26
.B 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.
.B sfdisk
(since version 2.26) aligns start and end of the partitions to
block-device I/O limits when specified by relative sizes, or when default
values expected.
.B sfdisk
does not create default system partitions for SGI and SUN disk label like
.BR fdisk (8).
It is necessary to explicitly create all partitions including whole-disk system
partitions.
.SH COMMANDS
The commands are mutually exclusive.
.TP
.RB [ \-N " \fIpartition-number\fR] " \fIdevice\fR
The default sfdisk command is to read the specification for the desired
partitioning of \fIdevice\fR from standard input, and then create a partition
table according to the specification. See below for the description of the input
format. If the standard input is a terminal then sfdisk starts interactive session.
If the option \fB\-N\fR specified then the changes are applied to the partition
addressed by \fIpartno\fR.
.TP
.BR \-a , " \-\-activate " \fIdevice\fR " "[\fIpartno\fR ...]
Switch on the bootable flag. If \fIpartno\fR no specified then lists all partitions
with enabled flag.
.TP
.BR \-d , " \-\-dump " \fIdevice\fR
Dump the partitions of a device in a format that is usable as input to sfdisk.
See the section "BACKUP PARTITION TABLE".
.TP
.BR \-g , " \-\-show-geometry " [\fIdevice\fR ...]
List geometry of all or specified devices.
.TP
.BR \-l , " \-\-list " [\fIdevice\fR ...]
List partitions of all or specified devices. This command can be used
together with \fB\-\-verify\fR.
.TP
.BR \-\-part\-attrs " " \fIdevice\fR " " \fIpartno\fR " "[\fIattrs\fR]
Change GPT partition attribute bits. If \fIattrs\fR no specified then print the current
partition setting. The \fIattrs\fR is comma or space delimited list of bits. The currently
supported attribute bits are: RequiredPartiton, NoBlockIOProtocol, LegacyBIOSBootable
and GUID specific bits in range from 48 to 63. For example string
"RequiredPartiton,50,51" sets three bits.
.TP
.BR \-\-part\-label " " \fIdevice\fR " " \fIpartno\fR " "[\fIlabel\fR]
Change GPT partition name (label). If \fIlabel\fR no specified then print the current
partition label.
.TP
.BR \-\-part-type " " \fIdevice\fR " " \fIpartno\fR " "[\fItype\fR]
Change partition type. If \fItype\fR no specified then print the current
partition type. The argument \fItype\fR is hex for MBR or GUID for GPT.
For backward compatibility the option -c, --id has the same meaning.
.TP
.BR \-\-part\-uuid " " \fIdevice\fR " " \fIpartno\fR " "[\fIuuid\fR]
Change GPT partition UUID. If \fIuuid\fR no specified then print the current
partition UUID.
.TP
.BR \-s , " \-\-show-size " [\fIdevice\fR ...]
List sizes of all or specified devices.
.TP
.BR \-T , " \-\-list-types
Print all supported types for the current disk label or label specified by
\fB\-\-label\fR.
.TP
.BR \-V , " \-\-verify
Test whether partition table and partitions seem correct.
.SH OPTIONS
.TP
.BR \-A , " \-\-append"
Don't create a new partition table, but rather appends specified partitions only.
.TP
.BR \-b , " \-\-backup"
Backup the current partition table sectors before start partitioning. The defautl
backup file name is ~/sfdisk-<device>-<offset>.bak, see \fI\-\-backup-file\fR.
.TP
.BR \-f , " \-\-force"
Disable all consistency checking.
.TP
.BR \-o , " \-\-output " \fIlist\fP
Specify which output columns to print. Use
.B \-\-help
to get a list of all supported columns.
The default list of columns may be extended if \fIlist\fP is
specified in the format \fI+list\fP (e.g. \fB-o +UUID\fP).
.TP
.BR \-O , " \-\-backup-file " \fIpath\fR
Override default backup file name. Note that the device name and offset is always
appended to the file name.
.TP
.BR \-q , " \-\-quiet"
Suppress extra info messages.
.TP
.BR \-n , " \-\-no\-act"
Do everything except write to device.
.TP
.BR "\-\-no\-reread"
Do not check by re-read-partition-table ioctl whether the device is in use.
.TP
.BR \-u , " \-\-unit " S
Deprecated option. The sector unit is supported only.
.TP
.BR "\-\-Linux"
Deprecated and ignored option. Linux (and another moder OS) compatible
partitioning is the default.
.TP
.BR \-X , " \-\-label \fItype\fR
Specify disk label type (e.g. dos, gpt, ...). If no label specified then sfdisk
defaults to an existing label. If there is no label on the device than defaults
to "dos".
.TP
.BR \-Y , " \-\-label-nested \fItype\fR
Force sfdisk to edit nested disk label. The primary disk label has to already exist.
This option allows to edit for example hybrid/protective MBR on devices with GPT.
.TP
.BR \-h , " \-\-help"
Display help text and exit.
.TP
.BR \-V , " \-\-version"
Display version information and exit.
.SH "INPUT FORMATS"
.B sfdisk
supports two input formats and generic header lines.
.B Header lines
.RS
The optional headers lines specify generic information that apply to partition
table. The header line format is:
.RS
.sp
.B "<name>: <value>"
.sp
.RE
The currently recognized headers are:
.RS
.TP
.B unit
Specify partitioning unit. The supported unit is only "sectors".
.TP
.B label
Specify partition table type. For example "dos" or "gpt".
.TP
.B label-id
Specify partition table identifier. It's hexadecimal number (with 0x prefix) for
MBR and UUID for GPT.
.RE
.sp
Note that header lines is possible to use only before the first partition
is specified in the input.
.RE
.B Unnamed fields format
.RS
.RS
.sp
.B "<start> <size> <type> <bootable>"
.sp
.RE
where each line fills one partition descriptor.
Fields are separated by whitespace, or comma or semicolon possibly followed by
whitespace; initial and trailing whitespace is ignored. Numbers can be octal,
decimal or hexadecimal, decimal is default. When a field is absent or empty,
a default value is used. But when the \fB-N\fR option (change a single partition
only) is given, the default for each field is its previous value.
The default value of
.I 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 default value of
.I size
is as much as possible (until next partition or end-of-device). A '+' can be
used instead of a number for size, which also means as much as possible. The
size may be followed by the multiplicative suffixes (KiB, MiB, GiB, TiB, PiB,
EiB, ZiB and YiB), then the number is interpreted as size of the partition in
bytes and then the size is aligned according to the device I/O limits.
The default is to interpret the number as number of sectors.
Patition
.I type
is given in hex for MBR (DOS), without the 0x prefix, GUID string for GPT or
shortcut:
.RS
.TP
.B L
Linux; means 83 for MBR and 0FC63DAF-8483-4772-8E79-3D69D8477DE4 for GPT.
.TP
.B S
swap area; means 82 for MBR and 0657FD6D-A4AB-43C4-84E5-0933C84B4F4F for GPT
.TP
.B E
extended partition; means 5 for MBR
.TP
.B H
home partition; means 933AC7E1-2EB4-4F13-B844-0E14E2AEF915 for GPT
.TP
.B X
linux extended partition; means 85 for MBR.
.RE
.I 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 might play a role for certain boot loaders and for other operating systems).
.RE
.B Named fields format
.RS
This format is more readable, robust, extendible and allows to specify additional
information (e.g. uuid). It's recommended to use this format to keep you scripts
more readable.
.RS
.sp
.B "[<device> :] <name>[=<value>], ..."
.sp
.RE
The
.I device
field is optional. sfdisk extracts partition number from the device name. It
allows to specify partition in random order. This functionality is mostly
used by \fR\-\-dump\fR. Don't use it if you are not sure.
The
.I value
can be between quotation marks (e.g. name="This is partition name"). The currently
supported fields:
.RS
.TP
.B 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.
.TP
.B size=<number>
Specify 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.
.TP
.B bootable
Mark partition as bootable.
.TP
.B attrs=<string>
Partition attributes, usually GPT partition attribute bits. See --part-attrs for
more details about GPT bits string format.
.TP
.B uuid=<string>
GPT partition UUID.
.TP
.B name=<string>
GPT partition name.
.TP
.B type=<code>
Hexadecimal number (without 0x) for MBR partition or GUID for GPT partition. For backward
compatibility \fBId=\fR field has the same meaning.
.RE
.RE
.SH "BACKUP PARTITION TABLE"
It's recommended to save device layout.
.B sfdisk
supports two ways.
Use \fB\-\-dump\fR command line option to save description of the device layout
to text file. The dump format is suitable for later sfdisk input. For example
.RS
.sp
.B "sfdisk --dump /dev/sda > sda.dump"
.sp
.RE
and restore by:
.RS
.sp
.B "sfdisk /dev/sda < sda.dump"
.RE
If you want to full (binary) backup of all sectors where is stored partition table
then use \fB\-\-backup\fR command line option. It writes the sectors to
~/sfdisk-<device>-<offset>.bak files. The default name of the backup file might
be changed by \fB\-\-backup\-file\fR command line option. The backup files
contain only raw data from the \fIdevice\fR. Note that the same concept of
backups files uses
.B wipefs (8)
.RS
.sp
.B "sfdisk --backup /dev/sda"
.sp
.RE
and later restore GPT header by:
.RS
.sp
.B dd if=~/sfdisk-sda-0x00000200.bak of=/dev/sda seek=$((0x00000200.bak)) bs=1 conv=notrunc
.sp
.RE
Note that sfdisk since version 2.26 does not provide \fB\-I\fR command line option to
restore sectors.
.B dd (1)
provides all necessary functionality.
.SH NOTES
sfdisk since version 2.26 does not provide \fB\-\-re\-read\fR command to force kernel to reread partition table. Use
\fBblockdev \-\-rereadpt\fR.
.PP
sfdisk since version 2.26 does not provide \fB\-\-DOS\fR, \fB\-\-IBM\fR, \fB\-\-DOS-extended\fR,
\fB\-\-unhide\fR, \fB\-\-show\-extended\fR, \fB\-\-cylinders\fR, \fB\-\-heads\fR, \fB\-\-sectors\fR,
\fB\-\-inside\-outer\fR, \fB\-\-not\-inside\-outer\fR options.
.SH ENVIRONMENT
.IP LIBFDISK_DEBUG=all
enables libfdisk debug output.
.IP LIBBLKID_DEBUG=all
enables libblkid debug output.
.IP LIBSMARTCOLS_DEBUG=all
enables libsmartcols debug output.
.SH "SEE ALSO"
.BR fdisk (8),
.BR cfdisk (8),
.BR parted (8),
.BR partprobe (8),
.BR partx(8)
.SH AUTHOR
Karel Zak <kzak@redhat.com>
.PP
The current sfdisk implementation is based on the original sfdisk
from Andries E. Brouwer.
.SH AVAILABILITY
The sfdisk command is part of the util-linux package and is available from
ftp://ftp.kernel.org/pub/linux/utils/util-linux/.
