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6dbe3af9 | 1 | .\" Copyright 1992, 1993 Rickard E. Faith (faith@cs.unc.edu) |
2b6fc908 | 2 | .\" Copyright 1998 Andries E. Brouwer (aeb@cwi.nl) |
6efb4b12 | 3 | .\" Copyright 2012 Davidlohr Bueso <dave@gnu.org> |
811d2ecc | 4 | .\" Copyright (C) 2013 Karel Zak <kzak@redhat.com> |
6dbe3af9 | 5 | .\" May be distributed under the GNU General Public License |
811d2ecc | 6 | .TH FDISK 8 "September 2013" "util-linux" "System Administration" |
eb2be4fd | 7 | |
6dbe3af9 | 8 | .SH NAME |
232dc924 | 9 | fdisk \- manipulate disk partition table |
eb2be4fd | 10 | |
6dbe3af9 | 11 | .SH SYNOPSIS |
57bc4707 | 12 | .B fdisk |
f49ccec2 | 13 | [options] |
57bc4707 | 14 | .I device |
2b6fc908 | 15 | .sp |
57bc4707 | 16 | .B fdisk \-l |
57bc4707 | 17 | .RI [ device ...] |
eb2be4fd | 18 | |
6dbe3af9 | 19 | .SH DESCRIPTION |
278f63c0 | 20 | .B fdisk |
811d2ecc | 21 | is a dialog-driven program for creation and manipulation of partition tables. |
870a6df5 | 22 | It understands GPT, MBR, Sun, SGI and BSD partition tables. |
278f63c0 | 23 | |
870a6df5 | 24 | Block devices can be divided into one or more logical disks called |
2b6fc908 | 25 | .IR partitions . |
a1939d70 BS |
26 | This division is recorded in the |
27 | .IR "partition table" , | |
811d2ecc | 28 | usually found in sector 0 of the disk. |
a1939d70 | 29 | (In the BSD world one talks about `disk slices' and a `disklabel'.) |
2b6fc908 | 30 | |
870a6df5 | 31 | All partitioning is driven by device I/O limits (the topology) by default. |
6dbe3af9 | 32 | .B fdisk |
870a6df5 BS |
33 | is able to optimize the disk layout for a 4K-sector size and use an alignment offset on |
34 | modern devices for MBR and GPT. It is always a good idea to follow \fBfdisk\fR's defaults | |
811d2ecc | 35 | as the default values (e.g. first and last partition sectors) and partition |
870a6df5 | 36 | sizes specified by the +<size>{M,G,...} notation are always aligned according |
811d2ecc | 37 | to the device properties. |
6dbe3af9 | 38 | |
811d2ecc | 39 | Note that |
870a6df5 BS |
40 | .BR partx (8) |
41 | provides a rich interface for scripts to print disk layouts, | |
42 | .B fdisk | |
43 | is mostly designed for humans. Backward compatibility in the output of | |
811d2ecc | 44 | .B fdisk |
870a6df5 | 45 | is not guaranteed. The input (the commands) should always be backward compatible. |
6dbe3af9 KZ |
46 | |
47 | .SH OPTIONS | |
48 | .TP | |
b06c1ca6 | 49 | \fB\-b\fR, \fB\-\-sector\-size\fR \fIsectorsize\fP |
870a6df5 BS |
50 | Specify the sector size of the disk. Valid values are 512, 1024, 2048, and 4096. |
51 | (Recent kernels know the sector size. Use this option only on old kernels or | |
eb2be4fd | 52 | to override the kernel's ideas.) Since util-linux-2.17, \fBfdisk\fR differentiates |
a1939d70 | 53 | between logical and physical sector size. This option changes both sector sizes to |
7f152745 | 54 | .IB sectorsize . |
6dbe3af9 | 55 | .TP |
e3a4aaa7 | 56 | \fB\-c\fR, \fB\-\-compatibility\fR[\fI=mode\fR] |
455fe9a0 | 57 | Specify the compatibility mode, 'dos' or 'nondos'. The default is non-DOS |
a1939d70 | 58 | mode. For backward compatibility, it is possible to use the option without |
eb2be4fd BS |
59 | the \fImode\fR argument -- then the default is used. Note that the optional |
60 | \fImode\fR argument cannot be separated from the \fB-c\fR option by a space, | |
e3a4aaa7 | 61 | the correct form is for example '-c=dos'. |
78498b7b | 62 | .TP |
e3a4aaa7 | 63 | \fB\-h\fR, \fB\-\-help\fR |
eb2be4fd | 64 | Display a help text and exit. |
a1939d70 | 65 | .TP |
e3a4aaa7 | 66 | \fB\-L\fR, \fB\-\-color\fR[\fI=when\fR] |
870a6df5 BS |
67 | Colorize the output in interactive mode. The optional argument \fIwhen\fP can |
68 | be \fBauto\fR, \fBnever\fR or \fBalways\fR. The default is \fBauto\fR. | |
80a1712f | 69 | .TP |
e3a4aaa7 | 70 | \fB\-l\fR, \fB\-\-list\fR |
eb63b9b8 KZ |
71 | List the partition tables for the specified devices and then exit. |
72 | If no devices are given, those mentioned in | |
73 | .I /proc/partitions | |
870a6df5 | 74 | (if that file exists) are used. |
6dbe3af9 | 75 | .TP |
fff8ad58 KZ |
76 | .BR \-o , " \-\-output " \fIlist\fP |
77 | Specify which output columns to print. Use | |
78 | .B \-\-help | |
79 | to get a list of all supported columns. | |
80 | ||
81 | The default list of columns may be extended if \fIlist\fP is | |
82 | specified in the format \fI+list\fP (e.g. \fB-o +UUID\fP). | |
83 | .TP | |
e3a4aaa7 KZ |
84 | \fB\-s\fR, \fB\-\-getsz\fR |
85 | Print the size in 512-byte sectors of each given block device. This option is DEPRECATED | |
9564e46c | 86 | in favour of |
870a6df5 | 87 | .BR blockdev (1). |
2b6fc908 | 88 | .TP |
e3a4aaa7 | 89 | \fB\-t\fR, \fB\-\-type\fR \fItype\fR |
870a6df5 BS |
90 | Enable support only for disklabels of the specified \fItype\fP, and disable |
91 | support for all other types. | |
565b7da6 | 92 | .TP |
e3a4aaa7 | 93 | \fB\-u\fR, \fB\-\-units\fR[\fI=unit\fR] |
a1939d70 BS |
94 | When listing partition tables, show sizes in 'sectors' or in 'cylinders'. The |
95 | default is to show sizes in sectors. For backward compatibility, it is possible | |
eb2be4fd BS |
96 | to use the option without the \fIunit\fR argument -- then the default is used. |
97 | Note that the optional \fIunit\fR argument cannot be separated from the \fB-u\fR | |
98 | option by a space, the correct form is for example '-u=cylinders'. | |
e3a4aaa7 KZ |
99 | |
100 | .TP | |
4b4e391a | 101 | \fB\-C\fR, \fB\-\-cylinders\fR \fInumber\fR |
e3a4aaa7 KZ |
102 | Specify the number of cylinders of the disk. |
103 | I have no idea why anybody would want to do so. | |
104 | .TP | |
4b4e391a | 105 | \fB\-H\fR, \fB\-\-heads\fR \fInumber\fR |
e3a4aaa7 KZ |
106 | Specify the number of heads of the disk. (Not the physical number, |
107 | of course, but the number used for partition tables.) | |
108 | Reasonable values are 255 and 16. | |
109 | .TP | |
4b4e391a | 110 | \fB\-S\fR, \fB\-\-sectors\fR \fInumber\fR |
e3a4aaa7 KZ |
111 | Specify the number of sectors per track of the disk. |
112 | (Not the physical number, of course, but the number used for | |
113 | partition tables.) A reasonable value is 63. | |
114 | ||
22853e4a | 115 | .TP |
e3a4aaa7 | 116 | \fB\-V\fR, \fB\-\-version\fR |
eb2be4fd | 117 | Display version information and exit. |
24505fb2 | 118 | |
811d2ecc KZ |
119 | .SH DEVICES |
120 | The | |
121 | .I device | |
122 | is usually /dev/sda, /dev/sdb or so. A device name refers to the entire disk. | |
123 | Old systems without libata (a library used inside the Linux kernel to support | |
124 | ATA host controllers and devices) make a difference between IDE and SCSI disks. | |
125 | In such cases the device name will be /dev/hd* (IDE) or /dev/sd* (SCSI). | |
126 | ||
127 | The | |
128 | .I partition | |
129 | is a device name followed by a partition number. For example, /dev/sda1 is the | |
130 | first partition on the first hard disk in the system. See also Linux kernel | |
131 | documentation (the Documentation/devices.txt file). | |
132 | ||
fd211531 KZ |
133 | .SH SIZES |
134 | The "last sector" dialog accepts partition size specified by number of sectors | |
135 | or by +<size>{K,B,M,G,...} notation. | |
136 | ||
137 | If the size is prefixed by '+' then it is interpreted as relative to the | |
138 | partition first sector. In this case the size is expected in bytes and the | |
139 | number may be followed by the multiplicative suffixes KiB=1024, MiB=1024*1024, | |
140 | and so on for GiB, TiB, PiB, EiB, ZiB and YiB. The "iB" is optional, e.g. "K" | |
141 | has the same meaning as "KiB". | |
142 | ||
143 | The relative sizes are always aligned according to device I/O limits. The | |
144 | +<size>{K,B,M,G,...} notation is recommended. | |
145 | ||
146 | For backward compatibility fdisk also accepts the suffixes KB=1000, | |
147 | MB=1000*1000, and so on for GB, TB, PB, EB, ZB and YB. These 10^N suffixes | |
148 | are deprecated. | |
149 | ||
a30e4ef4 KZ |
150 | .SH SCRIPT FILES |
151 | .B fdisk | |
152 | allows to read (by 'I' command) sfdisk compatible script files. The script is | |
153 | applied to in-memory partition table, and then it is possible to modify the | |
154 | partition table before you write it to the device. | |
155 | .PP | |
156 | And vice-versa it is possible to write the current in-memory disk layout | |
157 | to the script file by command 'O'. | |
158 | .PP | |
159 | The script files are compatible between cfdisk, sfdisk, fdisk and another | |
160 | libfdisk applications. For more details see | |
161 | .BR sfdisk (8). | |
162 | ||
811d2ecc KZ |
163 | .SH DISK LABELS |
164 | .B GPT (GUID Partition Table) | |
165 | .RS | |
870a6df5 BS |
166 | GPT is modern standard for the layout of the partition table. GPT uses 64-bit |
167 | logical block addresses, checksums, UUIDs and names for partitions and an | |
168 | unlimited number of partitions (although the number of partitions is | |
811d2ecc KZ |
169 | usually restricted to 128 in many partitioning tools). |
170 | ||
171 | Note that the first sector is still reserved for a | |
172 | .B protective MBR | |
870a6df5 BS |
173 | in the GPT specification. It prevents MBR-only partitioning tools |
174 | from mis-recognizing and overwriting GPT disks. | |
811d2ecc | 175 | |
870a6df5 | 176 | GPT is always a better choice than MBR, especially on modern hardware with a UEFI |
811d2ecc KZ |
177 | boot loader. |
178 | .RE | |
179 | ||
180 | .B DOS-type (MBR) | |
181 | .RS | |
870a6df5 | 182 | A DOS-type partition table can describe an unlimited number of partitions. In sector 0 |
811d2ecc KZ |
183 | there is room for the description of 4 partitions (called `primary'). One of |
184 | these may be an extended partition; this is a box holding logical partitions, | |
185 | with descriptors found in a linked list of sectors, each preceding the | |
186 | corresponding logical partitions. The four primary partitions, present or not, | |
870a6df5 | 187 | get numbers 1-4. Logical partitions are numbered starting from 5. |
811d2ecc KZ |
188 | |
189 | In a DOS-type partition table the starting offset and the size of each | |
190 | partition is stored in two ways: as an absolute number of sectors (given in 32 | |
191 | bits), and as a | |
192 | .B Cylinders/Heads/Sectors | |
193 | triple (given in 10+8+6 bits). The former is OK -- with 512-byte sectors this | |
194 | will work up to 2 TB. The latter has two problems. First, these C/H/S fields | |
195 | can be filled only when the number of heads and the number of sectors per track | |
196 | are known. And second, even if we know what these numbers should be, the 24 | |
197 | bits that are available do not suffice. DOS uses C/H/S only, Windows uses | |
870a6df5 | 198 | both, Linux never uses C/H/S. The |
811d2ecc | 199 | .B C/H/S addressing is deprecated |
0d0d12ad | 200 | and may be unsupported in some later fdisk version. |
811d2ecc | 201 | |
870a6df5 | 202 | .B Please, read the DOS-mode section if you want DOS-compatible partitions. |
811d2ecc | 203 | .B fdisk |
870a6df5 | 204 | does not care about cylinder boundaries by default. |
811d2ecc KZ |
205 | .RE |
206 | ||
870a6df5 | 207 | .B BSD/Sun-type |
811d2ecc | 208 | .RS |
870a6df5 | 209 | A BSD/Sun disklabel can describe 8 partitions, the third of which should be a `whole |
811d2ecc KZ |
210 | disk' partition. Do not start a partition that actually uses its first sector |
211 | (like a swap partition) at cylinder 0, since that will destroy the disklabel. | |
870a6df5 | 212 | Note that a |
811d2ecc | 213 | .B BSD label |
870a6df5 | 214 | is usually nested within a DOS partition. |
811d2ecc KZ |
215 | .RE |
216 | ||
217 | .B IRIX/SGI-type | |
218 | .RS | |
870a6df5 | 219 | An IRIX/SGI disklabel can describe 16 partitions, the eleventh of which should be an entire |
811d2ecc KZ |
220 | `volume' partition, while the ninth should be labeled `volume header'. The |
221 | volume header will also cover the partition table, i.e., it starts at block | |
222 | zero and extends by default over five cylinders. The remaining space in the | |
223 | volume header may be used by header directory entries. No partitions may | |
224 | overlap with the volume header. Also do not change its type or make some | |
225 | filesystem on it, since you will lose the partition table. Use this type of | |
226 | label only when working with Linux on IRIX/SGI machines or IRIX/SGI disks under | |
227 | Linux. | |
228 | .RE | |
229 | ||
870a6df5 | 230 | A sync() and an ioctl(BLKRRPART) (rereading the partition table from disk) |
811d2ecc KZ |
231 | are performed before exiting when the partition table has been updated. |
232 | ||
233 | .SH "DOS mode and DOS 6.x WARNING" | |
870a6df5 BS |
234 | .B Note that all this is deprecated. You don't have to care about things like |
235 | .B geometry and cylinders on modern operating systems. If you really want | |
236 | .B DOS-compatible partitioning then you have to enable DOS mode and cylinder | |
237 | .B units by using the '-c=dos -u=cylinders' fdisk command-line options. | |
811d2ecc KZ |
238 | |
239 | The DOS 6.x FORMAT command looks for some information in the first sector of | |
240 | the data area of the partition, and treats this information as more reliable | |
241 | than the information in the partition table. DOS FORMAT expects DOS FDISK to | |
242 | clear the first 512 bytes of the data area of a partition whenever a size | |
243 | change occurs. DOS FORMAT will look at this extra information even if the /U | |
244 | flag is given -- we consider this a bug in DOS FORMAT and DOS FDISK. | |
245 | ||
ba5ad6a4 | 246 | The bottom line is that if you use \fBfdisk\fR or \fBcfdisk\fR to change the |
870a6df5 BS |
247 | size of a DOS partition table entry, then you must also use |
248 | .BR dd "(1) to " "zero the first 512 bytes" | |
811d2ecc | 249 | of that partition before using DOS FORMAT to format the partition. For |
870a6df5 BS |
250 | example, if you were using \fBfdisk\fR to make a DOS partition table entry for |
251 | /dev/sda1, then (after exiting \fBfdisk\fR and rebooting Linux so that the | |
811d2ecc KZ |
252 | partition table information is valid) you would use the command "dd |
253 | if=/dev/zero of=/dev/sda1 bs=512 count=1" to zero the first 512 bytes of the | |
254 | partition. | |
255 | ||
256 | .B fdisk | |
870a6df5 | 257 | usually obtains the disk geometry automatically. This is not necessarily the |
811d2ecc | 258 | physical disk geometry (indeed, modern disks do not really have anything like a |
870a6df5 | 259 | physical geometry, certainly not something that can be described in the simplistic |
811d2ecc KZ |
260 | Cylinders/Heads/Sectors form), but it is the disk geometry that MS-DOS uses for |
261 | the partition table. | |
262 | ||
263 | Usually all goes well by default, and there are no problems if Linux is the | |
264 | only system on the disk. However, if the disk has to be shared with other | |
265 | operating systems, it is often a good idea to let an fdisk from another | |
266 | operating system make at least one partition. When Linux boots it looks at the | |
267 | partition table, and tries to deduce what (fake) geometry is required for good | |
268 | cooperation with other systems. | |
269 | ||
270 | Whenever a partition table is printed out in DOS mode, a consistency check is | |
271 | performed on the partition table entries. This check verifies that the | |
272 | physical and logical start and end points are identical, and that each | |
273 | partition starts and ends on a cylinder boundary (except for the first | |
274 | partition). | |
275 | ||
276 | Some versions of MS-DOS create a first partition which does not begin | |
277 | on a cylinder boundary, but on sector 2 of the first cylinder. | |
278 | Partitions beginning in cylinder 1 cannot begin on a cylinder boundary, but | |
279 | this is unlikely to cause difficulty unless you have OS/2 on your machine. | |
280 | ||
281 | For best results, you should always use an OS-specific partition table | |
282 | program. For example, you should make DOS partitions with the DOS FDISK | |
870a6df5 | 283 | program and Linux partitions with the Linux fdisk or Linux cfdisk programs. |
4ffbedba | 284 | .SH COLORS |
496c979a | 285 | Implicit coloring can be disabled by an empty file \fI/etc/terminal-colors.d/fdisk.disable\fR. |
811d2ecc | 286 | |
496c979a KZ |
287 | See |
288 | .BR terminal-colors.d (5) | |
289 | for more details about colorization configuration. The logical color names | |
290 | supported by | |
291 | .B fdisk | |
292 | are: | |
293 | .TP | |
294 | .B header | |
295 | The header of the output tables. | |
296 | .TP | |
297 | .B help-title | |
298 | The help section titles. | |
299 | .TP | |
300 | .B warn | |
301 | The warning messages. | |
302 | .TP | |
303 | .B welcome | |
304 | The welcome message. | |
4ffbedba | 305 | |
811d2ecc KZ |
306 | .SH AUTHORS |
307 | .MT kzak@redhat.com | |
308 | Karel Zak | |
309 | .ME | |
310 | .br | |
311 | .MT dave@gnu.org | |
312 | Davidlohr Bueso | |
313 | .ME | |
314 | .br | |
315 | .PP | |
316 | The original version was written by | |
317 | Andries E. Brouwer, A. V. Le Blanc and others. | |
318 | ||
24505fb2 | 319 | .SH ENVIRONMENT |
68e422ec KZ |
320 | .IP LIBFDISK_DEBUG=all |
321 | enables libfdisk debug output. | |
322 | .IP LIBBLKID_DEBUG=all | |
323 | enables libblkid debug output. | |
324 | .IP LIBSMARTCOLS_DEBUG=all | |
325 | enables libsmartcols debug output. | |
24505fb2 | 326 | |
612721db KZ |
327 | .SH "SEE ALSO" |
328 | .BR cfdisk (8), | |
c64061c9 | 329 | .BR sfdisk (8), |
63cccae4 | 330 | .BR mkfs (8), |
811d2ecc | 331 | .BR partx (8) |
eb2be4fd | 332 | |
86d62711 | 333 | .SH AVAILABILITY |
601d12fb KZ |
334 | The fdisk command is part of the util-linux package and is available from |
335 | ftp://ftp.kernel.org/pub/linux/utils/util-linux/. |