Linux shell--sfdisk manual
原本 要尝试着自己翻译下的，结果发现有人已经做好了。
转自：http://www.jinbuguo.com/man/sfdisk.html
SFDISK(8) System Administration SFDISK(8)
名称
sfdisk - 分区表操作工具
语法
sfdisk [options] device
sfdisk -s [partition]
描述
sfdisk 有4个主要用途：列出分区尺寸，列出分区表，检查分区表，创建分区表[非常危险]。
sfdisk 不能处理GPT格式的分区表，也不能处理超过2T的大硬盘，这种情况需要使用 GNU parted 工具。
sfdisk 并不会自动对齐分区，不过 fdisk(8) 可以。
列出分区尺寸
sfdisk -s [partition]
以块[blocks]为单位列出块设备的大小。
这里的[partition]可以是一个实际的分区(例如：/dev/sdb12)，也可以是一个完整的磁盘(例如：/dev/sda)
% sfdisk -s /dev/hda9
81599
如果省略[partition]参数，那么将依次列出每个磁盘(不含分区)的大小以及总计大小。
% sfdisk -s
/dev/hda: 208896
/dev/hdb: 1025136
/dev/hdc: 1031063
/dev/sda: 8877895
/dev/sdb: 1758927
total: 12901917 blocks
列出分区表
sfdisk -l [device]
列出device设备上的分区表。如果省略[device]参数，那么将列出所有磁盘上的分区表。
% 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
[说明]数字结尾的"+"或"-"表示其只是一个近似值而非精确值。
要查看精确值，可以使用 sfdisk -l -u S [device] 语法，按扇区查看。
检查分区表
sfdisk -V device
检查分区表的正确性，并打印出'OK'或者显示不合理之处。
例如：Warning: partition 1 does not end at a cylinder boundary
-V 选项可以和 -l 选项一起使用。在shell脚本内，可以使用
sfdisk -V -q device
来仅返回一个代表正确/错误的返回值
创建分区表
sfdisk device
根据标准输入(STDIN)给出的指示创建device的分区表。
这样便可以方便的在shell脚本内进行分区操作。
当 sfdisk 检测到其自身运行在终端内时，将会以交互方式操作，
否则(也就是在脚本内)，在检测到任何错误的时候，都将导致退出。
[警告]一个微小的输入错误都将可能导致数据丢失！
选项
-v, --version
打印版本信息并立即退出
-h, --help
打印帮助信息并立即退出
-T, --list-types
列出所有能够识别的分区类型(system ID)
-s, --show-size
列出分区的大小
-g, --show-geometry
列出内核检测到的设备的几何参数(C-H-S)
-G, --show-pt-geometry
列出根据设备上的分区表计算出的几何参数
-l, --list
列出设备上的分区表
-d, --dump
按照 sfdisk 可以理解的标准格式，打印出设备上目前现有的分区表，例如
% sfdisk -d /dev/hda > hda.out
之后还可以用如下命令重新写入分区表
% sfdisk /dev/hda < hda.out
-V, --verify
校验分区表的合理性
-i, --increment
柱面号(从 1 开始计数，而不是 0 )
-N number
仅更改指定序号的分区。例如
% sfdisk /dev/hdb -N5
,,,*
除了将 /dev/sdb 上的第五个分区标记为'bootable'之外，不做其他任何变更。
虽然这"第五个"分区很有可能叫做 /dev/sdb5 ，但是你也可能称它为别的名称，
例如'/my_equipment/disks/2/5'之类
-A, --activate[=device_or_number]
将指定编号的分区标记为'bootable'，并取消所有其他分区的'bootable'标记。
如果没有参数则表示列出带有'bootable'标记的分区，例如：
% sfdisk --activate /dev/sda
如果给出了设备参数，那么数字对应的分区将被标记为'bootable'，而其他分区则取消'bootable'标记。
例如下面的命令为 1,4 分区添加'bootable'，同时取消所有其他分区的'bootable'标记：
% sfdisk --activate=/dev/sda 1 4
如果只想激活一个分区的'bootable'标记，那么就必须将分区号作为参数。
例如，下面的命令表示开启第一个分区的'bootable'标记，同时取消所有其他分区的'bootable'标记：
% sfdisk --activate=1 /dev/sda
-c, --id num [Id]
如果没有给出[ID]参数，则打印出第num个分区的类型[ID]
如果给出[ID]参数，则将第num个分区的类型更改为ID
这个选项还有两个意思显而易见的别名：--print-id 和 --change-id
例如，打印 /dev/sdb5 的分区类型
% sfdisk --print-id /dev/sdb 5
6
接着再将 /dev/sdb5 的分区类型改为"0x83"
% sfdisk --change-id /dev/sdb 5 83
OK
-u, --unit letter
指定输入/输出的数字的单位。默认值是柱面。
这里的letter可以是 S[扇区], C[柱面], B[块], M[MB]。
-x, --show-extended
也包含扩展分区(无论对于输入还是输出)。
-C, --cylinders cylinders
强制指定柱面数，忽略内核自己的检测
-H, --heads heads
强制指定磁头数，忽略内核自己的检测
-S, --sectors sectors
强制指定扇区数，忽略内核自己的检测
-f, --force
强制执行，即使看上去是明显的错误动作
-q, --quiet
静默模式，禁止打印提示信息
-L, --Linux
不显示与Linux无关的警告
-n 模拟执行所有动作但并不实际写入磁盘
-R, --re-read
让内核重新读取分区表。
如果内核抱怨说：'device busy for revalidation (usage = 2)'
那就表明此设备上当前有尚未卸载的文件系统或者swap分区。
--no-reread
当执行分区表修改动作时，如果sfdisk检测到此设备已经被挂载或者正被用于swap，
那么将拒绝执行任何修改动作。使用该选项可以禁止这种检测。
[注意] --force 比这个选项更强，它表示无视一切禁忌的强制执行
理论
位于MBR(Master Boot Record)的磁盘分区表拥有如下数据结构：
struct partition {
unsigned char bootable; /* 0 or 0x80 , 1字节 */
hsc begin_head_sector_cylinder; /* 3字节 */
unsigned char id; /* 1字节 */
hsc end_head_sector_cylinder; /* 3字节 */
unsigned int starting_sector; /* 4字节 */
unsigned int num_of_sectors; /* 4字节 */
}
两个 hsc 字段指定了分区的开始和结束 head_sector_cylinder 值。
由于hsc字段只有24位，所以无法表示超过8G的值。而且当磁头数小于256的时候，所能表示的最大值更加的小。
事实上，Linux根本不看这两个字段的设置，因此这两个字段仅在磁盘引导的时候可能会有影响。
输入格式
sfdisk可以识别如下格式的输入行，每一行用于描述一个分区：
start size id bootable c,h,s c,h,s
字段之间可以用空格/逗号/分号进行分隔，首尾的空白都将被忽略。
数字可以是八进制/十进制(默认)/十六进制。
如果某个字段留空或者缺席，就表示使用其默认值。
两个 c,h,s 字段应该尽量留空，这样 sfdisk 可以根据几何参数以及 start 和 size 值进行推算。
bootable 可以指定为[*|-]格式，默认值是"-"也就是没有可引导标记。
这个标记仅对DOS有意义：DOS会给带有可引导标记的主分区分配 C: 盘符
id 应该以无"0x"前缀的格式给出其十六进制值，或者[E|S|L]简写字母：
L(83)是默认值，S(82,LINUX_SWAP)，E(5,扩展分区)。
start 的默认值是首个未分配的扇区/柱面
size 的默认值是尽可能大(直到下一个分区或磁盘尾)，设为'+'明确表示尽可能大。
当使用 -N 选项指定某个特定的分区时，每个字段的默认值就变成了原有分区表内已经存在的值。
这时候，可以将 size 设为'+'以明确表示尽可能大(直到下一个分区或磁盘尾)。
参见
cfdisk(8), fdisk(8), mkfs(8), parted(8), partprobe(8), kpartx(8)
util-linux August 2011 SFDISK(8)
下面是从系统里man的资料，英文原文：
SFDISK(8) Linux Programmer's Manual SFDISK(8)
NAME
sfdisk - Partition table manipulator for Linux
SYNOPSIS
sfdisk [options] device
sfdisk -s [partition]
DESCRIPTION
sfdisk has four (main) uses: list the size of a partition, list the parti-
tions on a device, check the partitions on a device, and - very dangerous
- repartition a device.
sfdisk doesn't understand GUID Partition Table (GPT) and it is not
designed for large partitions. In particular case use more advanced GNU
parted(8).
Note that sfdisk does not align partitions to block device I/O limits.
This functionality is provided by fdisk(8).
List Sizes
sfdisk -s partition gives the size of partition in blocks. This may be
useful in connection with programs like mkswap(8) or so. Here partition is
usually something like /dev/hda1 or /dev/sdb12, but may also be an entire
disk, like /dev/xda.
% sfdisk -s /dev/hda9
81599
%
If the partition argument is omitted, sfdisk will list the sizes of all
disks, and the total:
% sfdisk -s
/dev/hda: 208896
/dev/hdb: 1025136
/dev/hdc: 1031063
/dev/sda: 8877895
/dev/sdb: 1758927
total: 12901917 blocks
%
List Partitions
The second type of invocation: sfdisk -l [options] device will list the
partitions on this device. If the device argument is omitted, the parti-
tions on all hard disks are listed.
% 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
%
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.
Check partitions
The third type of invocation: sfdisk -V device will apply various consis-
tency checks to the partition tables on device. It prints 'OK' or com-
plains. The -V option can be used together with -l. In a shell script one
might use sfdisk -V -q device which only returns a status.
Create partitions
The fourth type of invocation: sfdisk device will cause sfdisk to read the
specification for the desired partitioning of device from its standard
input, and then to change the partition tables on that disk. Thus, it is
possible to use sfdisk from a shell script. When sfdisk determines that
its standard input is a terminal, it will be conversational; otherwise it
will abort on any error.
BE EXTREMELY CAREFUL - ONE TYPING MISTAKE AND ALL YOUR DATA IS LOST
As a precaution, one can save the sectors changed by sfdisk:
% sfdisk /dev/hdd -O hdd-partition-sectors.save
...
%
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
% sfdisk /dev/hdd -I hdd-partition-sectors.save
%
(This is not the same as saving the old partition table: a readable ver-
sion 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.
OPTIONS
-v or --version
Print version number of sfdisk and exit immediately.
-? or --help
Print a usage message and exit immediately.
-T or --list-types
Print the recognized types (system Id's).
-s or --show-size
List the size of a partition.
-g or --show-geometry
List the kernel's idea of the geometry of the indicated disk(s).
-G or --show-pt-geometry
List the geometry of the indicated disks guessed by looking at the
partition table.
-l or --list
List the partitions of a device.
-d Dump the partitions of a device in a format useful as input to
sfdisk. For example,
% sfdisk -d /dev/hda > hda.out
% sfdisk /dev/hda < hda.out
will correct the bad last extended partition that the OS/2 fdisk
creates.
-V or --verify
Test whether partitions seem correct. (See above.)
-i or --increment
Number cylinders etc. starting from 1 instead of 0.
-N number
Change only the single partition indicated. For example:
% sfdisk /dev/hdb -N5
,,,*
%
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).
-A number
Make the indicated partition(s) active, and all others inactive.
-c 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:
% sfdisk --print-id /dev/hdb 5
6
% sfdisk --change-id /dev/hdb 5 83
OK
first reports that /dev/hdb5 has Id 6, and then changes that into
83.
-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.
-x or --show-extended
Also list non-primary extended partitions on output, and expect
descriptors for them on input.
-C cylinders
Specify the number of cylinders, possibly overriding what the ker-
nel thinks.
-H heads
Specify the number of heads, possibly overriding what the kernel
thinks.
-S sectors
Specify the number of sectors, possibly overriding what the kernel
thinks.
-f or --force
Do what I say, even if it is stupid.
-q or --quiet
Suppress warning messages.
-L or --Linux
Do not complain about things irrelevant for Linux.
-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 parti-
tion, then 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.
-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. Of course one can only know where cylinder bound-
aries are when one knows what geometry DOS will use for this disk.)
--IBM or --leave-last
Certain IBM diagnostic programs assume that they can use the last
cylinder on a disk for disk-testing purposes. If you think you
might ever run such programs, use this option to tell sfdisk that
it should not allocate the last cylinder. Sometimes the last
cylinder contains a bad sector table.
-n Go through all the motions, but do not actually write to disk.
-R Only execute the BLKRRPART ioctl (to make the kernel re-read the
partition table). This can be useful for checking in advance that
the final BLKRRPART will be successful, and also when you changed
the partition table 'by hand' (e.g., using dd from a backup). If
the kernel complains ('device busy for revalidation (usage = 2)')
then something still uses the device, and you still have to unmount
some file system, or say swapoff to some swap partition.
--no-reread
When starting a repartitioning of a disk, sfdisk checks that this
disk is not mounted, or in use as a swap device, and refuses to
continue if it is. This option suppresses the test. (On the other
hand, the -f option would force sfdisk to continue even when this
test fails.)
-O file
Just before writing the new partition, output the sectors that are
going to be overwritten to file (where hopefully file resides on
another disk, or on a floppy).
-I file
After destroying your filesystems with an unfortunate sfdisk com-
mand, you would have been able to restore the old situation if only
you had preserved it using the -O flag.
THEORY
Block 0 of a disk (the Master Boot Record) contains among other things
four partition descriptors. The partitions described here are called pri-
mary partitions.
A partition descriptor has 6 fields:
struct partition {
unsigned char bootable; /* 0 or 0x80 */
hsc begin_hsc;
unsigned char id;
hsc end_hsc;
unsigned int starting_sector;
unsigned int nr_of_sectors;
}
The two hsc fields indicate head, sector and cylinder of the begin and the
end of the partition. Since each hsc field only takes 3 bytes, only 24
bits are available, which does not suffice for big disks (say > 8GB). In
fact, due to the wasteful representation (that uses a byte for the number
of heads, which is typically 16), problems already start with 0.5GB. How-
ever Linux does not use these fields, and problems can arise only at boot
time, before Linux has been started. For more details, see the lilo docu-
mentation.
Each partition has a type, its 'Id', and if this type is 5 or f ('extended
partition') the starting sector of the partition again contains 4 parti-
tion descriptors. MSDOS only uses the first two of these: the first one an
actual data partition, and the second one again an extended partition (or
empty). In this way one gets a chain of extended partitions. Other oper-
ating systems have slightly different conventions. Linux also accepts
type 85 as equivalent to 5 and f - this can be useful if one wants to have
extended partitions under Linux past the 1024 cylinder boundary, without
DOS FDISK hanging. (If there is no good reason, you should just use 5,
which is understood by other systems.)
Partitions that are not primary or extended are called logical. Often,
one cannot boot from logical partitions (because the process of finding
them is more involved than just looking at the MBR). Note that of an
extended partition only the Id and the start are used. There are various
conventions about what to write in the other fields. One should not try to
use extended partitions for data storage or swap.
INPUT FORMAT
sfdisk reads lines of the form
where each line fills one partition descriptor.
Fields are separated by whitespace, or comma or semicolon possibly fol-
lowed 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.
The
them from
or specified using the -H, -S, -C flags.
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. For example, when there are several primary DOS parti-
tions, DOS assigns C: to the first among these that is bootable.)
Id is given in hex, without the 0x prefix, or is [E|S|L|X], where L
(LINUX_NATIVE (83)) is the default, S is LINUX_SWAP (82), E is
EXTENDED_PARTITION (5), and X is LINUX_EXTENDED (85).
The default value of start is the first nonassigned sector/cylinder/...
The default value of size is as much as possible (until next partition or
end-of-disk).
However, for the four partitions inside an extended partition, the
defaults are: Linux partition, Extended partition, Empty, Empty.
But when the -N option (change a single partition only) is given, the
default for each field is its previous value.
EXAMPLE
The command
sfdisk /dev/hdc << EOF
0,407
,407
;
;
EOF
will partition /dev/hdc just as indicated above.
The command
sfdisk /dev/hdb << EOF
,3,L
,60,L
,19,S
,,E
,130,L
,130,L
,130,L
,,L
EOF
will partition /dev/hdb into two Linux partitions of 3 and 60 cylinders, a
swap space of 19 cylinders, and an extended partition covering the rest.
Inside the extended partition there are four Linux logical partitions,
three of 130 cylinders and one covering the rest.
With the -x option, the number of input lines must be a multiple of 4: you
have to list the two empty partitions that you never want using two blank
lines. Without the -x option, you give one line for the partitions inside
a extended partition, instead of four, and terminate with end-of-file
(^D). (And sfdisk will assume that your input line represents the first
of four, that the second one is extended, and the 3rd and 4th are empty.)
DOS 6.x WARNING
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 infor-
mation even if the /U flag is given -- we consider this a bug in DOS FOR-
MAT and DOS FDISK.
The bottom line is that if you use sfdisk to change the size of a DOS par-
tition table entry, then you must also use dd to zero the first 512 bytes
of that partition before using DOS FORMAT to format the partition. For
example, if you were using sfdisk to make a DOS partition table entry for
/dev/hda1, then (after exiting sfdisk and rebooting Linux so that the par-
tition table information is valid) you would use the command "dd
if=/dev/zero of=/dev/hda1 bs=512 count=1" to zero the first 512 bytes of
the partition. BE EXTREMELY CAREFUL if you use the dd command, since a
small typo can make all of the data on your disk useless.
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 sfdisk program.