1UDFLABEL(8) System Manager's Manual UDFLABEL(8)
2
6 udflabel — show or change UDF filesystem label
7
10 udflabel [encoding-options] [block-options] [identifier-options] device
11 [new-label]
12
15 When udflabel is invoked without identifier-options and without speci‐
16 fying new-label then it shows current label of UDF filesystem on device
17 to standard output terminated by new line. Otherwise it updates UDF
18 filesystem (up to the revision 2.60) on device with new specified iden‐
19 tifiers from identifier-options. Specifying new-label is synonym for
20 both --lvid and --vid, see section UDF LABEL AND UUID.
21
24 GENERAL OPTIONS
25 -h,--help
26 Display the usage and the list of options.
27 BLOCK OPTIONS
30 -b,--blocksize= block-size
31 Specify the size of blocks in bytes. Valid block size for a UDF
32 filesystem is a power of two in the range from 512 to 32768 and
33 must match a device logical (sector) size. If omitted, udflabel
34 tries to autodetect block size. First it tries logical (sector)
35 size and then all valid block sizes.
36 --startblock= start-block
39 Specify the block location where the UDF filesystem starts. It
40 is used for calculating the block location of the Volume Recog‐
41 nition Sequence (32 kB after the start block) and the first An‐
42 chor Volume Descriptor Pointer (256 blocks after the start
43 block).
44 Normally start block is 0, but for Multisession UDF optical
46 discs it is the block location where the last session of Multi‐
47 session UDF disc starts.
48 If omitted, udflabel for optical disc tries to detect start
50 block of the last session from disc Table Of Contents. Otherwise
51 value 0 is used.
52 For accessing some previous session of Multisession UDF optical
54 disc, it is required to specify correct block where that previ‐
55 ous session starts. And also to specify where that session ends
56 via --lastblock option.
57 For Multisession UDF disc images stored in file there is no way
59 to detect where the last session starts and therefore it is nec‐
60 essary to specify the correct start block location manually from
61 the original optical disc Table Of Contents.
62 (Option available since udflabel 2.3)
64 --lastblock= last-block
67 Specify the block location where the UDF filesystem ends. It is
68 used for calculating the block location of second and third An‐
69 chor Volume Descriptor Pointer (256 blocks prior the last block
70 and the last block itself).
71 Normally last block is number of disk blocks minus one, but for
73 Multisession UDF optical discs when reading different session
74 than the last one (specified by --startblock) it is the block
75 location where the specified session ends.
76 If omitted, udflabel for optical disc tried to detect the last
78 recorded block with fallback to the last block of device or disk
79 file image.
80 For accessing some previous session of Multisession UDF optical
82 disc, it is required to specify correct value for both --start‐
83 block and --lastblock options.
84 (Option available since udflabel 2.3)
86 --vatblock= vat-block
89 Specify the block location of the Virtual Allocation Table. Vir‐
90 tual Allocation Table is present only on UDF disks with Virtual
91 Partition Map and must be at the last written/recorded disk
92 block.
93 If omitted, udflabel for optical disc tries to detect the last
95 recorded block with fallback to the last block of block device
96 or disk file image or block specified by --lastblock. In most
97 cases, this fallback does not have to work and for disk file im‐
98 ages with Virtual Allocation Table it is necessary to specify
99 the correct location.
100 Virtual Allocation Table contains Logical Volume Identifier (UDF
102 Label).
103 --force
106 Force updating UDF disks without write support or write pro‐
107 tected UDF disks. Some UDF disks may have set write protect
108 flag. Some media, like CD-ROM, DVD-ROM or BD-ROM are read-only.
109 Other media, like CD-RW or DVD-RW, are write-once. UDF is de‐
110 signed also for such media where updating Label or Identifiers
111 is not possible. But in some rare cases, it could make sense to
112 try and overwrite the existing Label or Identifiers also for UDF
113 filesystem which has Access Type either Read-Only or Recordable
114 (Write-Once). This is possible only if underlying media supports
115 overwriting. E.g. UDF image of CD-ROM stored on hard disk or
116 Read-Only UDF image burned to DVD-RAM or BD-RE discs. Option
117 --force ignores UDF Access Type and treats it as Overwritable.
118 Also it ignores UDF SoftWriteProtect and HardWriteProtected
119 flags.
120 -n,--no-write
123 Not really, do not write to device. Just simulate and display
124 what would happen with device. Useful for determining which UDF
125 blocks would be overwritten.
126 IDENTIFIER OPTIONS
129 -u,--uuid= uuid
130 Specify the UDF uuid. Must be exactly 16 hexadecimal lowercase
131 digits and is used for first 16 characters of --fullvsid option.
132 Special value random generates new uuid from local time and a
133 random number. See section UDF LABEL AND UUID.
134 --lvid= new-logical-volume-identifier
137 Specify the new Logical Volume Identifier.
138 --vid= new-volume-identifier
141 Specify the new Volume Identifier.
142 --vsid= new-volume-set-identifier
145 Specify the new 17.–127. character of Volume Set Identifier. See
146 section UDF LABEL AND UUID.
147 --fsid= new-file-set-identifier
150 Specify the new File Set Identifier.
151 --fullvsid= new-full-volume-set-identifier
154 Specify the new Volume Set identifier. Overwrite previous --uuid
155 and --vsid options. See section UDF LABEL AND UUID.
156 --owner= new-owner-name
159 Specify the new Owner name, person who created the medium or
160 filesystem. It is stored in UDF Logical Volume Info1, part of
161 UDF Implementation Use Volume Descriptor. (Option available
162 since udflabel 2.3)
163 --organization= new-organization-name
166 Specify the new Organization name responsible for creating the
167 medium or filesystem. It is stored in UDF Logical Volume Info2,
168 part of UDF Implementation Use Volume Descriptor. (Option avail‐
169 able since udflabel 2.3)
170 --contact= new-contact-information
173 Specify the new Contact information for the medium or filesys‐
174 tem. It is stored in UDF Logical Volume Info3, part of UDF Im‐
175 plementation Use Volume Descriptor. (Option available since ud‐
176 flabel 2.3)
177 --appid= new-application-identifier
180 Specify the new Application Identifier which identifies applica‐
181 tion that created medium or filesystem. It is stored in UDF Pri‐
182 mary Volume Descriptor. This identifier can be empty or must
183 start with * and contain only 7bit ASCII characters. (Option
184 available since udflabel 2.3)
185 --impid= new-developer-identifier
188 Specify the new Developer Identifier for Implementation Identi‐
189 fier. It is unique identification of the implementation which
190 created medium or filesystem. It is stored in UDF Primary Volume
191 Descriptor. This identifier must start with * and contain only
192 7bit ASCII characters. (Option available since udflabel 2.3)
193 ENCODING OPTIONS
196 --locale
197 Treat identifier string options as strings encoded according to
198 current locale settings (default). Must be specified as the
199 first argument.
200 --u8 Treat identifier string options as strings encoded in 8-bit OSTA
203 Compressed Unicode format without leading Compression ID byte,
204 which is equivalent to Latin1 (ISO-8859-1). Must be specified as
205 first argument.
206 --u16 Treat identifier string options as strings encoded in 16-bit
209 OSTA Compressed Unicode format without leading Compression ID
210 byte, which is equivalent to UTF-16BE. Note that it is not pos‐
211 sible to include zero byte in command line options, therefore
212 any character which has at least one zero byte cannot be sup‐
213 plied (this applies to all Latin1 characters). Must be specified
214 as the first argument.
215 --utf8 Treat identifier string options as strings encoded in UTF-8.
218 Must be specified as the first argument.
219
222 UDF specification does not say anything about a disk label but it de‐
223 scribes that UDF Logical Volume Identifier is an extremely important
224 field for media identification in a jukebox as that field is displayed
225 to the user. And based on this statement it is a common practice for
226 the majority of UDF implementations to use UDF Logical Volume Identi‐
227 fier as a UDF disk label.
228 UDF specification does not have a concept of disk UUID like other
230 filesystems. But mandates that the first 16 characters of UDF Volume
231 Set Identifier are unique, a non-fixed and a non-trivial value. Plus
232 first eight characters are hexadecimal digits. Windows application for‐
233 mat.exe and Mac OS X application newfs_udf are known to violates this
234 requirement and set only the first 8 characters as unique (others are
235 fixed). Since, there are still a lot of UDF implementations which use
236 in the first 16 characters only hexadecimal digits and all compliant
237 UDF implementations have hexadecimal digits in the first 8 characters,
238 the following algorithm for generating stable UUID was informally cho‐
239 sen and now is used by udftools, util-linux, grub2 and other projects:
240 0. If Volume Set Identifier has less then 8 characters then stop
242 with empty UUID
243 1. Take the first 16 bytes from UTF-8 encoded string of Volume
244 Set Identifier
245 2. If all bytes are hexadecimal digits then use their lowercase
246 form as UUID
247 3. If first 8 bytes are not all hexadecimal digits then convert
248 those 8 bytes to their hexadecimal representation (resulting in
249 16 bytes) and use as UUID
250 4. Otherwise, compose UUID from two 8 byte parts:
251 1. part: Use the lowercase form of the first 8 bytes
252 (which are hexadecimal digits)
253 2. part: Convert next 4 bytes (9.–12. pos.) to their
254 hexadecimal representation
255 Which means that this generated UUID has always 16 hexadecimal lower‐
257 case digits. In most cases, this UUID matches case-insensitively the
258 first 16 characters of UDF Volume Set Identifier and for all disks com‐
259 pliant to the UDF specification the first 8 bytes of UUID matches case-
260 insensitively the first 8 characters of UDF Volume Set Identifier. In
261 that algorithm was chosen UTF-8 encoding because it is the only com‐
262 monly used Unicode transformation to bytes with fixed points in all
263 hexadecimal digits.
264
267 udflabel returns 0 if successful, non-zero if there are problems like
268 block device does not contain UDF filesystem or updating failed.
269
272 udflabel is not able to set new Label, Logical Volume Identifier and
273 File Set Identifier for disks with Virtual Allocation Table (used by
274 Write Once media).
275 udflabel prior to version 2.3 was unable to handle Multisession UDF
277 discs correctly. It always accessed only the first session (the oldest
278 one) and not the last session (the most recent).
279 udflabel prior to version 2.2 was unable to print and process Unicode
281 strings with code points above U+FFFF correctly. When option --utf8 was
282 specified then input strings were limited to 3-byte UTF-8 sequences and
283 when option --u16 was specified then input strings were limited just to
284 UCS-2BE strings (subset of UTF-16BE).
285 udflabel prior to version 2.2 ignored UDF SoftWriteProtect and Hard‐
287 WriteProtected flags and overwritten such disks without any notice.
288 udflabel prior to version 2.2 was not able to set a new Label, Logical
290 Volume Identifier and File Set Identifier for disks with Metadata Par‐
291 tition (used by UDF revisions higher then 2.01).
292 udflabel prior to version 2.1 was not able to read Label correctly if
294 the disk had Virtual Allocation Table stored outside of Information
295 Control Block.
296
299 Pali Rohár <pali.rohar@gmail.com>
300
303 udflabel is part of the udftools package since version 2.0 and is
304 available from https://github.com/pali/udftools/.
305
308 mkudffs(8), pktsetup(8), cdrwtool(1), udfinfo(1), wrudf(1)
309Commands udftools UDFLABEL(8)