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1 .\" Copyright (c) 2002 Marcel Moolenaar
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25 .\" $FreeBSD: src/sbin/gpt/gpt.8,v 1.17 2006/06/22 22:22:32 marcel Exp $
26 .\" $DragonFly: src/sbin/gpt/gpt.8,v 1.4 2007/12/23 15:31:28 swildner Exp $
27 .\"
28 .Dd June 22, 2006
29 .Os
30 .Dt GPT 8
31 .Sh NAME
32 .Nm gpt
33 .Nd "GUID partition table maintenance utility"
34 .Sh SYNOPSIS
35 .Nm
36 .Op Ar general_options
37 .Ar command
38 .Op Ar command_options
39 .Ar device ...
40 .Sh DESCRIPTION
41 The
42 .Nm
43 utility provides the necessary functionality to manipulate GUID partition
44 tables (GPTs), but see
45 .Sx BUGS
46 below for how and where functionality is missing.
47 The basic usage model of the
48 .Nm
49 tool follows that of the
50 .Xr cvs 1
51 tool.
52 The general options are described in the following paragraph.
53 The remaining paragraphs describe the individual commands with their options.
54 Here we conclude by mentioning that a
55 .Ar device
56 is either a special file
57 corresponding to a disk-like device or a regular file.
58 The command is applied to each
59 .Ar device
60 listed on the command line.
61 .Ss General Options
62 The general options allow the user to change default settings or otherwise
63 change the behaviour that is applicable to all commands.
64 Not all commands use all default settings, so some general options may not
65 have an effect on all commands.
66 .Pp
67 The
68 .Fl p Ar count
69 option allows the user to change the number of partitions the GPT can
70 accommodate.
71 This is used whenever a new GPT is created.
72 By default, the
73 .Nm
74 utility will create space for 128 partitions (or 32 sectors of 512 bytes).
75 .Pp
76 The
77 .Fl r
78 option causes the
79 .Nm
80 utility to open the device for reading only.
81 Currently this option is primarily useful for the
82 .Ic show
83 command, but the intent
84 is to use it to implement dry-run behaviour.
85 .Pp
86 The
87 .Fl v
88 option controls the verbosity level.
89 The level increases with every occurrence of this option.
90 There is no formalized definition of the different levels yet.
91 .Ss Commands
92 .Bl -tag -width indent
93 .\" ==== add ====
94 .It Xo
95 .Nm
96 .Ic add
97 .Op Fl b Ar number
98 .Op Fl i Ar index
99 .Op Fl s Ar count
100 .Op Fl t Ar type
101 .Ar device ...
102 .Xc
103 The
104 .Ic add
105 command allows the user to add a new partition to an existing table.
106 By default, it will create a UFS partition covering the first available block
107 of an unused disk space.
108 The command-specific options can be used to control this behaviour.
109 .Pp
110 The
111 .Fl b Ar number
112 option allows the user to specify the starting (beginning) sector number of
113 the partition.
114 The minimum sector number is 1, but has to fall inside an unused region of
115 disk space that is covered by the GPT.
116 .Pp
117 The
118 .Fl i Ar index
119 option allows the user to specify which (free) entry in the GPT table is to
120 be used for the new partition.
121 By default, the first free entry is selected.
122 Entries start at index 0 representing partition 0 of the GPT.
123 .Pp
124 The
125 .Fl s Ar count
126 option allows the user to specify the size of the partition in sectors.
127 The minimum size is 1.
128 .Pp
129 The
130 .Fl t Ar type
131 option allows the user to specify the partition type.
132 The type is given as an UUID, but
133 .Nm
134 accepts
135 .Cm efi , swap , ufs , hfs , linux , dfly ,
136 and
137 .Cm windows
138 as aliases for the most commonly used partition types.
139 You may also specify any symbolic name in the system uuids file.
140 .\" ==== create ====
141 .It Nm Ic create Oo Fl fp Oc Ar device ...
142 The
143 .Ic create
144 command allows the user to create a new (empty) GPT.
145 By default, one cannot create a GPT when the device contains a MBR,
146 however this can be overridden with the
147 .Fl f
148 option.
149 If the
150 .Fl f
151 option is specified, an existing MBR is destroyed and any partitions
152 described by the MBR are lost.
153 .Pp
154 The
155 .Fl p
156 option tells
157 .Nm
158 to create only the primary table and not the backup table.
159 This option is only useful for debugging and should not be used otherwise.
160 .\" ==== destroy ====
161 .It Nm Ic destroy Oo Fl r Oc Ar device ...
162 The
163 .Ic destroy
164 command allows the user to destroy an existing, possibly not empty GPT.
165 .Pp
166 The
167 .Fl r
168 option instructs
169 .Nm
170 to destroy the table in a way that it can be recovered.
171 .\" ==== label ====
172 .It Xo
173 .Nm
174 .Ic label
175 .Op Fl a
176 .Aq Fl f Ar file | Fl l Ar label
177 .Ar device ...
178 .Xc
179 .It Xo
180 .Nm
181 .Ic label
182 .Op Fl b Ar number
183 .Op Fl i Ar index
184 .Op Fl s Ar count
185 .Op Fl t Ar type
186 .Aq Fl f Ar file | Fl l Ar label
187 .Ar device ...
188 .Xc
189 The
190 .Ic label
191 command allows the user to label any partitions that match the selection.
192 At least one of the following selection options must be specified.
193 .Pp
194 The
195 .Fl a
196 option specifies that all partitions should be labeled.
197 It is mutually exclusive with all other selection options.
198 .Pp
199 The
200 .Fl b Ar number
201 option selects the partition that starts at the given block number.
202 .Pp
203 The
204 .Fl i Ar index
205 option selects the partition with the given partition number.
206 Partition numbers start at 0.
207 .Pp
208 The
209 .Fl s Ar count
210 option selects all partitions that have the given size.
211 This can cause multiple partitions to be removed.
212 .Pp
213 The
214 .Fl t Ar type
215 option selects all partitions that have the given type.
216 The type is given as an UUID or by the aliases that the
217 .Ic add
218 command accepts.
219 This can cause multiple partitions to be removed.
220 .Pp
221 The
222 .Fl f Ar file
223 or
224 .Fl l Ar label
225 options specify the new label to be assigned to the selected partitions.
226 The
227 .Fl f Ar file
228 option is used to read the label from the specified file.
229 Only the first line is read from the file and the trailing newline
230 character is stripped.
231 If the file name is the dash or minus sign
232 .Pq Fl ,
233 the label is read from
234 the standard input.
235 The
236 .Fl l Ar label
237 option is used to specify the label in the command line.
238 The label is assumed to be encoded in UTF-8.
239 .\" ==== migrate ====
240 .It Nm Ic migrate Oo Fl fs Oc Ar device ...
241 The
242 .Ic migrate
243 command allows the user to migrate an MBR-based disk partitioning into a
244 GPT-based partitioning.
245 By default, the MBR is not migrated when it contains partitions of an unknown
246 type.
247 This can be overridden with the
248 .Fl f
249 option.
250 Specifying the
251 .Fl f
252 option will cause unknown partitions to be ignored and any data in it
253 to be lost.
254 .Pp
255 The
256 .Fl s
257 option prevents migrating
258 .Bx
259 disk labels into GPT partitions by creating
260 the GPT equivalent of a slice.
261 .\" ==== remove ====
262 .It Nm Ic remove Oo Fl a Oc Ar device ...
263 .It Xo
264 .Nm
265 .Ic remove
266 .Op Fl b Ar number
267 .Op Fl i Ar index
268 .Op Fl s Ar count
269 .Op Fl t Ar type
270 .Ar device ...
271 .Xc
272 The
273 .Ic remove
274 command allows the user to remove any and all partitions that match the
275 selection.
276 It uses the same selection options as the
277 .Ic label
278 command.
279 See above for a description of these options.
280 Partitions are removed by clearing the partition type.
281 No other information is changed.
282 .\" ==== show ====
283 .It Nm Ic show Oo Fl lu Oc Ar device ...
284 The
285 .Ic show
286 command displays the current partitioning on the listed devices and gives
287 an overall view of the disk contents.
288 With the
289 .Fl l
290 option the GPT partition label will be displayed instead of the GPT partition
291 type.
292 The option has no effect on non-GPT partitions.
293 With the
294 .Fl u
295 option the GPT partition type is displayed as an UUID instead of in a
296 user friendly form.
297 The
298 .Fl l
299 option takes precedence over the
300 .Fl u
301 option.
302 .El
303 .Sh SEE ALSO
304 .Xr fdisk 8 ,
305 .Xr mount 8 ,
306 .Xr newfs 8 ,
307 .Xr swapon 8
308 .Sh HISTORY
309 The
310 .Nm
311 utility appeared in
312 .Fx 5.0
313 for ia64.
314 .Sh BUGS
315 The development of the
316 .Nm
317 utility is still work in progress.
318 Many necessary features are missing or partially implemented.
319 In practice this means that the manual page, supposed to describe these
320 features, is farther removed from being complete or useful.
321 As such, missing functionality is not even documented as missing.
322 However, it is believed that the currently present functionality is reliable
323 and stable enough that this tool can be used without bullet-proof footware if
324 one thinks one does not make mistakes.
325 .Pp
326 It is expected that the basic usage model does not change, but it is
327 possible that future versions will not be compatible in the strictest sense
328 of the word.
329 For example, the
330 .Fl p Ar count
331 option may be changed to a command option rather than a generic option.
332 There are only two commands that use it so there is a chance that the natural
333 tendency for people is to use it as a command option.
334 Also, options primarily intended for diagnostic or debug purposes may be
335 removed in future versions.
336 .Pp
337 Another possibility is that the current usage model is accompanied by
338 other interfaces to make the tool usable as a back-end.
339 This all depends on demand and thus feedback.