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1 .\" $NetBSD: dd.1,v 1.27 2015/03/18 13:30:13 wiz Exp $
2 .\"
3 .\" Copyright (c) 1990, 1993
4 .\" The Regents of the University of California. All rights reserved.
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6 .\" This code is derived from software contributed to Berkeley by
7 .\" Keith Muller of the University of California, San Diego.
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33 .\" @(#)dd.1 8.2 (Berkeley) 1/13/94
34 .\"
35 .Dd March 18, 2015
36 .Dt DD 1
37 .Os
38 .Sh NAME
39 .Nm dd
40 .Nd convert and copy a file
41 .Sh SYNOPSIS
42 .Nm
43 .Op operand ...
44 .Sh DESCRIPTION
45 The
46 .Nm
47 utility copies the standard input to the standard output.
48 Input data is read and written in 512-byte blocks.
49 If input reads are short, input from multiple reads are aggregated
50 to form the output block.
51 When finished,
52 .Nm
53 displays the number of complete and partial input and output blocks
54 and truncated input records to the standard error output.
55 .Pp
56 The following operands are available:
57 .Bl -tag -width of=file
58 .It Cm bs= Ns Ar n
59 Set both input and output block size, superseding the
60 .Cm ibs
61 and
62 .Cm obs
63 operands.
64 If no conversion values other than
65 .Cm noerror ,
66 .Cm notrunc
67 or
68 .Cm sync
69 are specified, then each input block is copied to the output as a
70 single block without any aggregation of short blocks.
71 .It Cm cbs= Ns Ar n
72 Set the conversion record size to
73 .Va n
74 bytes.
75 The conversion record size is required by the record oriented conversion
76 values.
77 .It Cm count= Ns Ar n
78 Copy only
79 .Va n
80 input blocks.
81 .It Cm files= Ns Ar n
82 Copy
83 .Va n
84 input files before terminating.
85 This operand is only applicable when the input device is a tape.
86 .It Cm ibs= Ns Ar n
87 Set the input block size to
88 .Va n
89 bytes instead of the default 512.
90 .It Cm if= Ns Ar file
91 Read input from
92 .Ar file
93 instead of the standard input.
94 .It Cm iflag= Ns Ar flags
95 Use comma-separated
96 .Ar flags
97 when calling
98 .Xr open 2
99 for the input file.
100 The possible values are
101 .Va O_
102 flags documented in
103 .Xr open 2 ,
104 specified as lowercase and with the leading
105 .Va O_
106 removed.
107 Default value is
108 .Va rdonly .
109 .It Cm iseek= Ns Ar n
110 Seek on the input file
111 .Ar n
112 blocks.
113 This is synonymous with
114 .Cm skip= Ns Ar n .
115 .It Cm msgfmt= Ns Ar fmt
116 Specify the message format
117 .Ar fmt
118 to be used when writing information to standard output.
119 Possible values are:
120 .Bl -tag -width xxxxx -offset indent -compact
121 .It quiet
122 turns off information summary report except for errors and
123 .Cm progress .
124 .It posix
125 default information summary report as specified by POSIX.
126 .It human
127 default information summary report extended with human-readable
128 values.
129 .El
130 .Pp
131 When
132 .Ar fmt
133 does not correspond to any value given above,
134 it contains a string that will be used as format specifier
135 for the information summary output.
136 Each conversion specification is introduced by the character
137 .Cm % .
138 The following ones are available:
139 .Bl -tag -width xx -offset indent -compact
140 .It b
141 total number of bytes transferred
142 .It B
143 total number of bytes transferred in
144 .Xr humanize_number 3
145 format
146 .It e
147 speed transfer
148 .It E
149 speed transfer in
150 .Xr humanize_number 3
151 format
152 .It i
153 number of partial input block(s)
154 .It I
155 number of full input block(s)
156 .It o
157 number of partial output block(s)
158 .It O
159 number of full output block(s)
160 .It s
161 time elapsed since the beginning in
162 .Do seconds.ms Dc
163 format
164 .It p
165 number of sparse output blocks
166 .It t
167 number of truncated blocks
168 .It w
169 number of odd-length swab blocks
170 .It P
171 singular/plural of
172 .Do block Dc
173 depending on number of sparse blocks
174 .It T
175 singular/plural of
176 .Do block Dc
177 depending on number of truncated blocks
178 .It W
179 singular/plural of
180 .Do block Dc
181 depending on number of swab blocks
182 .El
183 .It Cm obs= Ns Ar n
184 Set the output block size to
185 .Va n
186 bytes instead of the default 512.
187 .It Cm of= Ns Ar file
188 Write output to
189 .Ar file
190 instead of the standard output.
191 Any regular output file is truncated unless the
192 .Cm notrunc
193 conversion value is specified.
194 If an initial portion of the output file is skipped (see the
195 .Cm seek
196 operand)
197 the output file is truncated at that point.
198 .It Cm oflag= Ns Ar flags
199 Same as
200 .Cm iflag
201 but for the call to
202 .Xr open 2
203 on the output file.
204 The default value is
205 .Va creat ,
206 which should be explicitly added in
207 .Cm oflag
208 in order to output to a nonexistent file.
209 The default or specified value is or'ed with
210 .Va rdwr
211 for a first
212 .Xt open 2
213 attempt, then on failure with
214 .Va wronly
215 on a second attempt.
216 In both cases,
217 .Va trunc
218 is automatically added if none of
219 .Cm oseek ,
220 .Cm seek ,
221 or
222 .Cm conv=notrunc
223 operands are used,
224 .It Cm oseek= Ns Ar n
225 Seek on the output file
226 .Ar n
227 blocks.
228 This is synonymous with
229 .Cm seek= Ns Ar n .
230 .It Cm seek= Ns Ar n
231 Seek
232 .Va n
233 blocks from the beginning of the output before copying.
234 On non-tape devices, an
235 .Xr lseek 2
236 operation is used.
237 Otherwise, existing blocks are read and the data discarded.
238 If the user does not have read permission for the tape, it is positioned
239 using the tape
240 .Xr ioctl 2
241 function calls.
242 If the seek operation is past the end of file, space from the current
243 end of file to the specified offset is filled with blocks of
244 .Tn NUL
245 bytes.
246 .It Cm skip= Ns Ar n
247 Skip
248 .Va n
249 blocks from the beginning of the input before copying.
250 On input which supports seeks, an
251 .Xr lseek 2
252 operation is used.
253 Otherwise, input data is read and discarded.
254 For pipes, the correct number of bytes is read.
255 For all other devices, the correct number of blocks is read without
256 distinguishing between a partial or complete block being read.
257 .It Cm progress= Ns Ar n
258 Switch on display of progress if
259 .Va n
260 is set to any non-zero value.
261 This will cause a
262 .Dq \&.
263 to be printed (to the standard error output) for every
264 .Va n
265 full or partial blocks written to the output file.
266 .Sm off
267 .It Cm conv= Cm value Op \&, Cm value \&...
268 .Sm on
269 Where
270 .Cm value
271 is one of the symbols from the following list.
272 .Bl -tag -width unblock
273 .It Cm ascii , oldascii
274 The same as the
275 .Cm unblock
276 value except that characters are translated from
277 .Tn EBCDIC
278 to
279 .Tn ASCII
280 before the
281 records are converted.
282 (These values imply
283 .Cm unblock
284 if the operand
285 .Cm cbs
286 is also specified.)
287 There are two conversion maps for
288 .Tn ASCII .
289 The value
290 .Cm ascii
291 specifies the recommended one which is compatible with
292 .At V .
293 The value
294 .Cm oldascii
295 specifies the one used in historic
296 .Tn AT\*[Am]T
297 and pre-
298 .Bx 4.3 Reno
299 systems.
300 .It Cm block
301 Treats the input as a sequence of newline or end-of-file terminated variable
302 length records independent of input and output block boundaries.
303 Any trailing newline character is discarded.
304 Each input record is converted to a fixed length output record where the
305 length is specified by the
306 .Cm cbs
307 operand.
308 Input records shorter than the conversion record size are padded with spaces.
309 Input records longer than the conversion record size are truncated.
310 The number of truncated input records, if any, are reported to the standard
311 error output at the completion of the copy.
312 .It Cm ebcdic , ibm , oldebcdic , oldibm
313 The same as the
314 .Cm block
315 value except that characters are translated from
316 .Tn ASCII
317 to
318 .Tn EBCDIC
319 after the
320 records are converted.
321 (These values imply
322 .Cm block
323 if the operand
324 .Cm cbs
325 is also specified.)
326 There are four conversion maps for
327 .Tn EBCDIC .
328 The value
329 .Cm ebcdic
330 specifies the recommended one which is compatible with
331 .At V .
332 The value
333 .Cm ibm
334 is a slightly different mapping, which is compatible with the
335 .At V
336 .Cm ibm
337 value.
338 The values
339 .Cm oldebcdic
340 and
341 .Cm oldibm
342 are maps used in historic
343 .Tn AT\*[Am]T
344 and pre
345 .Bx 4.3 Reno
346 systems.
347 .It Cm lcase
348 Transform uppercase characters into lowercase characters.
349 .It Cm noerror
350 Do not stop processing on an input error.
351 When an input error occurs, a diagnostic message followed by the current
352 input and output block counts will be written to the standard error output
353 in the same format as the standard completion message.
354 If the
355 .Cm sync
356 conversion is also specified, any missing input data will be replaced
357 with
358 .Tn NUL
359 bytes (or with spaces if a block oriented conversion value was
360 specified) and processed as a normal input buffer.
361 If the
362 .Cm sync
363 conversion is not specified, the input block is omitted from the output.
364 On input files which are not tapes or pipes, the file offset
365 will be positioned past the block in which the error occurred using
366 .Xr lseek 2 .
367 .It Cm notrunc
368 Do not truncate the output file.
369 This will preserve any blocks in the output file not explicitly written
370 by
371 .Nm .
372 The
373 .Cm notrunc
374 value is not supported for tapes.
375 .It Cm osync
376 Pad the final output block to the full output block size.
377 If the input file is not a multiple of the output block size
378 after conversion, this conversion forces the final output block
379 to be the same size as preceding blocks for use on devices that require
380 regularly sized blocks to be written.
381 This option is incompatible with use of the
382 .Cm bs= Ns Ar n
383 block size specification.
384 .It Cm sparse
385 If one or more non-final output blocks would consist solely of
386 .Dv NUL
387 bytes, try to seek the output file by the required space instead of
388 filling them with
389 .Dv NUL Ns s .
390 This results in a sparse file on some file systems.
391 .It Cm swab
392 Swap every pair of input bytes.
393 If an input buffer has an odd number of bytes, the last byte will be
394 ignored during swapping.
395 .It Cm sync
396 Pad every input block to the input buffer size.
397 Spaces are used for pad bytes if a block oriented conversion value is
398 specified, otherwise
399 .Tn NUL
400 bytes are used.
401 .It Cm ucase
402 Transform lowercase characters into uppercase characters.
403 .It Cm unblock
404 Treats the input as a sequence of fixed length records independent of input
405 and output block boundaries.
406 The length of the input records is specified by the
407 .Cm cbs
408 operand.
409 Any trailing space characters are discarded and a newline character is
410 appended.
411 .El
412 .El
413 .Pp
414 Where sizes are specified, a decimal number of bytes is expected.
415 Two or more numbers may be separated by an
416 .Dq x
417 to indicate a product.
418 Each number may have one of the following optional suffixes:
419 .Bl -tag -width 3n -offset indent -compact
420 .It b
421 Block; multiply by 512
422 .It k
423 Kibi; multiply by 1024 (1 KiB)
424 .It m
425 Mebi; multiply by 1048576 (1 MiB)
426 .It g
427 Gibi; multiply by 1073741824 (1 GiB)
428 .It t
429 Tebi; multiply by 1099511627776 (1 TiB)
430 .It w
431 Word; multiply by the number of bytes in an integer
432 .El
433 .Pp
434 When finished,
435 .Nm
436 displays the number of complete and partial input and output blocks,
437 truncated input records and odd-length byte-swapping blocks to the
438 standard error output.
439 A partial input block is one where less than the input block size
440 was read.
441 A partial output block is one where less than the output block size
442 was written.
443 Partial output blocks to tape devices are considered fatal errors.
444 Otherwise, the rest of the block will be written.
445 Partial output blocks to character devices will produce a warning message.
446 A truncated input block is one where a variable length record oriented
447 conversion value was specified and the input line was too long to
448 fit in the conversion record or was not newline terminated.
449 .Pp
450 Normally, data resulting from input or conversion or both are aggregated
451 into output blocks of the specified size.
452 After the end of input is reached, any remaining output is written as
453 a block.
454 This means that the final output block may be shorter than the output
455 block size.
456 .Pp
457 If
458 .Nm
459 receives a
460 .Dv SIGINFO
461 signal
462 (see the
463 .Ic status
464 argument for
465 .Xr stty 1 ) ,
466 the current input and output block counts will
467 be written to the standard error output
468 in the same format as the standard completion message.
469 If
470 .Nm
471 receives a
472 .Dv SIGINT
473 signal, the current input and output block counts will
474 be written to the standard error output
475 in the same format as the standard completion message and
476 .Nm
477 will exit.
478 .Sh EXIT STATUS
479 The
480 .Nm
481 utility exits 0 on success and \*[Gt]0 if an error occurred.
482 .Sh EXAMPLES
483 To print summary information in human-readable form:
484 .Pp
485 .Dl dd if=/dev/zero of=/dev/null count=1 msgfmt=human
486 .Pp
487 To customize the information summary output and print it through
488 .Xr unvis 3 :
489 .Pp
490 .Bd -literal -offset indent
491 dd if=/dev/zero of=/dev/null count=1 \e
492 msgfmt='speed:%E, in %s seconds\en' 2\*[Gt]\*[Am]1 | unvis
493 .Ed
494 .Sh SEE ALSO
495 .Xr cp 1 ,
496 .Xr mt 1 ,
497 .Xr tr 1
498 .Sh STANDARDS
499 The
500 .Nm
501 utility is expected to be a superset of the
502 .St -p1003.2
503 standard.
504 The
505 .Cm files
506 and
507 .Cm msgfmt
508 operands and the
509 .Cm ascii ,
510 .Cm ebcdic ,
511 .Cm ibm ,
512 .Cm oldascii ,
513 .Cm oldebcdic
514 and
515 .Cm oldibm
516 values are extensions to the
517 .Tn POSIX
518 standard.