sfdisk.8

Util-linux 软件包包含许多工具。其中比较重要的是加载、卸载、格式化、分区和管理硬盘驱动器

.\" Copyright 1995 Andries E. Brouwer ([e-mail])
.\" May be distributed under the GNU General Public License
.\" The `DOS 6.x Warning' was taken from the old fdisk.8, which says
.\" -- Copyright 1992, 1993 Rickard E. Faith ([e-mail])
.\" -- May be distributed under the GNU General Public License
.\" The `DRDOS Warning' was taken from a net post by Stephen Tweedie.
.\"
.TH SFDISK 8 "1 September 1995" "Linux" "Linux Programmer's Manual"
.SH NAME
sfdisk \- Partition table manipulator for Linux
.SH SYNOPSIS
.BR sfdisk " [options] device"
.br
.BR "sfdisk \-s " [partition]
.SH DESCRIPTION
.B sfdisk
has four (main) uses: list the size of a partition, list the partitions
on a device, check the partitions on a device, and - very dangerous -
repartition a device.

.SS "List Sizes"
.BI "sfdisk \-s " partition
gives the size of
.I partition
in blocks. This may be useful in connection with programs like
.B mkswap
or so. Here
.I partition
is usually something like
.I /dev/hda1
or
.IR /dev/sdb12 ,
but may also be an entire disk, like
.IR /dev/xda .
.br
.RS
.nf
.if t .ft CW
% sfdisk \-s /dev/hda9
81599
%
.if t .ft R
.fi
.RE
If the partition argument is omitted,
.B sfdisk
will list the sizes of all disks, and the total:
.br
.RS
.nf
.if t .ft CW
% sfdisk \-s
/dev/hda: 208896
/dev/hdb: 1025136
/dev/hdc: 1031063
/dev/sda: 8877895
/dev/sdb: 1758927
total: 12901917 blocks
%
.if t .ft R
.fi
.RE

.SS "List Partitions"
The second type of invocation:
.BI "sfdisk \-l " "[options] device"
will list the partitions on this device.
If the device argument is omitted, the partitions on all hard disks
are listed.
.br
.nf
.if t .ft CW
% sfdisk \-l /dev/hdc

Disk /dev/hdc: 16 heads, 63 sectors, 2045 cylinders
Units = cylinders of 516096 bytes, blocks of 1024 bytes, counting from 0

   Device Boot Start     End   #cyls   #blocks   Id  System
/dev/hdc1          0+    406     407\-   205096+  83  Linux native
/dev/hdc2        407     813     407    205128   83  Linux native
/dev/hdc3        814    2044    1231    620424   83  Linux native
/dev/hdc4          0       \-       0         0    0  Empty
%
.if t .ft R
.fi
The trailing \- and + signs indicate that rounding has taken place,
and that the actual value is slightly less (more).
To see the exact values, ask for a listing with sectors as unit.

.SS "Check partitions"
The third type of invocation:
.BI "sfdisk \-V " device
will apply various consistency checks to the partition tables on
.IR device .
It prints `OK' or complains. The \-V option can be used together
with \-l. In a shell script one might use
.BI "sfdisk \-V \-q " device
which only returns a status.

.SS "Create partitions"
The fourth type of invocation:
.BI "sfdisk " device
will cause
.B sfdisk
to read the specification for the desired partitioning of
.I device
from its standard input, and then to change the partition tables
on that disk. Thus, it is possible to use
.B sfdisk
from a shell script. When
.B sfdisk
determines that its standard input is a terminal, it will be
conversational; otherwise it will abort on any error.
.LP
BE EXTREMELY CAREFUL - ONE TYPING MISTAKE AND ALL YOUR DATA IS LOST
.LP
As a precaution, one can save the sectors changed by
.BR sfdisk :
.RS
.nf
.if t .ft CW
% sfdisk /dev/hdd \-O hdd-partition-sectors.save
\&...
%
.if t .ft R
.fi
.RE
.LP
Then, if you discover that you did something stupid before anything
else has been written to disk, it may be possible to recover
the old situation with
.RS
.nf
.if t .ft CW
% sfdisk /dev/hdd \-I hdd-partition-sectors.save
%
.if t .ft R
.fi
.RE
.LP
(This is not the same as saving the old partition table:
a readable version of the old partition table can be saved
using the \-d option. However, if you create logical partitions,
the sectors describing them are located somewhere on disk,
possibly on sectors that were not part of the partition table
before. Thus, the information the \-O option saves is not a binary
version of the output of \-d.)

There are many options.

.SH OPTIONS
.TP
.BR \-v " or " \-\-version
Print version number of
.B sfdisk
and exit immediately.
.TP
.BR \-? " or " \-\-help
Print a usage message and exit immediately.
.TP
.BR \-T " or " \-\-list\-types
Print the recognized types (system Id's).
.TP
.BR \-s " or " \-\-show\-size
List the size of a partition.
.TP
.BR \-g " or " \-\-show\-geometry
List the kernel's idea of the geometry of the indicated disk(s).
.TP
.BR \-l " or " \-\-list
List the partitions of a device.
.TP
.BR \-d
Dump the partitions of a device in a format useful as input
to sfdisk. For example,
.br
.nf
.if t .ft CW
    % sfdisk -d /dev/hda > hda.out
    % sfdisk /dev/hda < hda.out
.if t .ft R
.fi
will correct the bad last extended partition that the OS/2
fdisk creates.
.TP
.BR \-V " or " \-\-verify
Test whether partitions seem correct. (See above.)
.TP
.BR \-i " or " \-\-increment
Number cylinders etc. starting from 1 instead of 0.
.TP
.BI \-N " number"
Change only the single partition indicated. For example:
.br
.nf
.if t .ft CW
    % sfdisk /dev/hdb \-N5
    ,,,*
    %
.if t .ft R
.fi
will make the fifth partition on /dev/hdb bootable (`active')
and change nothing else. (Probably this fifth partition
is called /dev/hdb5, but you are free to call it something else,
like `/my_equipment/disks/2/5' or so).
.TP
.BI \-A "number"
Make the indicated partition(s) active, and all others inactive.
.TP
.BI \-c "\fR or " \-\-id " number [Id]"
If no Id argument given: print the partition Id of the indicated
partition. If an Id argument is present: change the type (Id) of
the indicated partition to the given value.
This option has the two very long forms \-\-print\-id and \-\-change\-id.
For example:
.br
.nf
.if t .ft CW
    % sfdisk --print-id /dev/hdb 5
    6
    % sfdisk --change-id /dev/hdb 5 83
    OK
.if t .ft R
.fi
first reports that /dev/hdb5 has Id 6, and then changes that into 83.
.TP
.BR \-uS " or " \-uB " or " \-uC " or " \-uM
Accept or report in units of sectors (blocks, cylinders, megabytes,
respectively). The default is cylinders, at least when the geometry
is known.
.TP
.BR \-x " or " \-\-show\-extended
Also list non-primary extended partitions on output,
and expect descriptors for them on input.
.TP
.BI \-C " cylinders"
Specify the number of cylinders, possibly overriding what the kernel thinks.
.TP
.BI \-H " heads"
Specify the number of heads, possibly overriding what the kernel thinks.
.TP
.BI \-S " sectors"
Specify the number of sectors, possibly overriding what the kernel thinks.
.TP
.BR \-f " or " \-\-force
Do what I say, even if it is stupid.
.TP
.BR \-q " or " \-\-quiet
Suppress warning messages.
.TP
.BR \-L " or " \-\-Linux
Do not complain about things irrelevant for Linux.
.TP
.BR \-D " or " \-\-DOS
For DOS-compatibility: waste a little space.
(More precisely: if a partition cannot contain sector 0,
e.g. because that is the MBR of the device, or contains
the partition table of an extended partition, then
.B sfdisk
would make it start the next sector. However, when this
option is given it skips to the start of the next track,
wasting for example 33 sectors (in case of 34 sectors/track),
just like certain versions of DOS do.)
Certain Disk Managers and boot loaders (such as OSBS, but not
LILO or the OS/2 Boot Manager) also live in this empty space,
so maybe you want this option if you use one.
.TP
.BR \-E " or " \-\-DOS\-extended
Take the starting sector numbers of "inner" extended partitions
to be relative to the starting cylinder boundary of the outer one,
(like some versions of DOS do) rather than to the starting sector
(like Linux does).
(The fact that there is a difference here means that one should
always let extended partitions start at cylinder boundaries if
DOS and Linux should interpret the partition table in the same way.