summaryrefslogtreecommitdiff
path: root/bin/dd/dd.1
blob: 44ea896fcbda13fabad26d5ba7933c576b4c8dfc (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
.\"	$NetBSD: dd.1,v 1.36 2019/01/30 10:28:50 wiz Exp $
.\"
.\" Copyright (c) 1990, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" Keith Muller of the University of California, San Diego.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"	@(#)dd.1	8.2 (Berkeley) 1/13/94
.\"
.Dd January 29, 2019
.Dt DD 1
.Os
.Sh NAME
.Nm dd
.Nd convert and copy a file
.Sh SYNOPSIS
.Nm
.Op operand ...
.Sh DESCRIPTION
The
.Nm
utility copies the standard input to the standard output.
Input data is read and written in 512-byte blocks.
If input reads are short, input from multiple reads are aggregated
to form the output block.
When finished,
.Nm
displays the number of complete and partial input and output blocks
and truncated input records to the standard error output.
.Pp
The following operands are available:
.Bl -tag -width of=file
.It Cm bs= Ns Ar n
Set both input and output block size, superseding the
.Cm ibs
and
.Cm obs
operands.
If no conversion values other than
.Cm noerror ,
.Cm notrunc
or
.Cm sync
are specified, then each input block is copied to the output as a
single block without any aggregation of short blocks.
.It Cm cbs= Ns Ar n
Set the conversion record size to
.Va n
bytes.
The conversion record size is required by the record oriented conversion
values.
.It Cm count= Ns Ar n
Copy only
.Va n
input blocks.
.It Cm files= Ns Ar n
Copy
.Va n
input files before terminating.
This operand is only applicable when the input device is a tape.
.It Cm ibs= Ns Ar n
Set the input block size to
.Va n
bytes instead of the default 512.
.It Cm if= Ns Ar file
Read input from
.Ar file
instead of the standard input.
.It Cm iflag= Ns Ar flags
Use comma-separated
.Ar flags
when calling
.Xr open 2
for the input file.
See the
.Sx INPUT AND OUTPUT FLAGS
section for details.
Default value is
.Va rdonly .
.It Cm iseek= Ns Ar n
Seek on the input file
.Ar n
blocks.
This is synonymous with
.Cm skip= Ns Ar n .
.It Cm msgfmt= Ns Ar fmt
Specify the message format
.Ar fmt
to be used when writing information to standard output.
Possible values are:
.Bl -tag -width xxxxx -offset indent -compact
.It quiet
turns off information summary report except for errors and
.Cm progress .
.It posix
default information summary report as specified by POSIX.
.It human
default information summary report extended with human-readable
values.
.El
.Pp
When
.Ar fmt
does not correspond to any value given above,
it contains a string that will be used as format specifier
for the information summary output.
Each conversion specification is introduced by the character
.Cm % .
The following ones are available:
.Bl -tag -width xx -offset indent -compact
.It b
total number of bytes transferred
.It B
total number of bytes transferred in
.Xr humanize_number 3
format
.It e
speed transfer
.It E
speed transfer in
.Xr humanize_number 3
format
.It i
number of partial input block(s)
.It I
number of full input block(s)
.It o
number of partial output block(s)
.It O
number of full output block(s)
.It s
time elapsed since the beginning in
.Do seconds.ms Dc
format
.It p
number of sparse output blocks
.It t
number of truncated blocks
.It w
number of odd-length swab blocks
.It P
singular/plural of
.Do block Dc
depending on number of sparse blocks
.It T
singular/plural of
.Do block Dc
depending on number of truncated blocks
.It W
singular/plural of
.Do block Dc
depending on number of swab blocks
.El
.It Cm obs= Ns Ar n
Set the output block size to
.Va n
bytes instead of the default 512.
.It Cm of= Ns Ar file
Write output to
.Ar file
instead of the standard output.
Any regular output file is truncated unless the
.Cm notrunc
conversion value is specified.
If an initial portion of the output file is skipped (see the
.Cm seek
operand)
the output file is truncated at that point.
.It Cm oflag= Ns Ar flags
Same as
.Cm iflag
but for the call to
.Xr open 2
on the output file.
The default value is
.Va creat ,
which must be explicitly added in
.Cm oflag
if this option is used in order to output to a nonexistent file.
The default or specified value is or'ed with
.Va rdwr
for a first
.Xr open 2
attempt, then on failure with
.Va wronly
on a second attempt.
In both cases,
.Va trunc
is automatically added if none of
.Cm oseek ,
.Cm seek ,
or
.Cm conv=notrunc
operands are used.
See the
.Sx INPUT AND OUTPUT FLAGS
section for details.
.It Cm oseek= Ns Ar n
Seek on the output file
.Ar n
blocks.
This is synonymous with
.Cm seek= Ns Ar n .
.It Cm seek= Ns Ar n
Seek
.Va n
blocks from the beginning of the output before copying.
On non-tape devices, an
.Xr lseek 2
operation is used.
Otherwise, existing blocks are read and the data discarded.
If the user does not have read permission for the tape, it is positioned
using the tape
.Xr ioctl 2
function calls.
If the seek operation is past the end of file, space from the current
end of file to the specified offset is filled with blocks of
.Tn NUL
bytes.
.It Cm skip= Ns Ar n
Skip
.Va n
blocks from the beginning of the input before copying.
On input which supports seeks, an
.Xr lseek 2
operation is used.
Otherwise, input data is read and discarded.
For pipes, the correct number of bytes is read.
For all other devices, the correct number of blocks is read without
distinguishing between a partial or complete block being read.
.It Cm progress= Ns Ar n
Switch on display of progress if
.Va n
is set to any non-zero value.
This will cause a
.Dq \&.
to be printed (to the standard error output) for every
.Va n
full or partial blocks written to the output file.
.Sm off
.It Cm conv= Cm value Op \&, Cm value \&...
.Sm on
Where
.Cm value
is one of the symbols from the following list.
.Bl -tag -width unblock
.It Cm ascii , oldascii
The same as the
.Cm unblock
value except that characters are translated from
.Tn EBCDIC
to
.Tn ASCII
before the
records are converted.
(These values imply
.Cm unblock
if the operand
.Cm cbs
is also specified.)
There are two conversion maps for
.Tn ASCII .
The value
.Cm ascii
specifies the recommended one which is compatible with
.At V .
The value
.Cm oldascii
specifies the one used in historic
.Tn AT&T
and pre-
.Bx 4.3 Reno
systems.
.It Cm block
Treats the input as a sequence of newline or end-of-file terminated variable
length records independent of input and output block boundaries.
Any trailing newline character is discarded.
Each input record is converted to a fixed length output record where the
length is specified by the
.Cm cbs
operand.
Input records shorter than the conversion record size are padded with spaces.
Input records longer than the conversion record size are truncated.
The number of truncated input records, if any, are reported to the standard
error output at the completion of the copy.
.It Cm ebcdic , ibm , oldebcdic , oldibm
The same as the
.Cm block
value except that characters are translated from
.Tn ASCII
to
.Tn EBCDIC
after the
records are converted.
(These values imply
.Cm block
if the operand
.Cm cbs
is also specified.)
There are four conversion maps for
.Tn EBCDIC .
The value
.Cm ebcdic
specifies the recommended one which is compatible with
.At V .
The value
.Cm ibm
is a slightly different mapping, which is compatible with the
.At V
.Cm ibm
value.
The values
.Cm oldebcdic
and
.Cm oldibm
are maps used in historic
.Tn AT&T
and pre
.Bx 4.3 Reno
systems.
.It Cm lcase
Transform uppercase characters into lowercase characters.
.It Cm noerror
Do not stop processing on an input error.
When an input error occurs, a diagnostic message followed by the current
input and output block counts will be written to the standard error output
in the same format as the standard completion message.
If the
.Cm sync
conversion is also specified, any missing input data will be replaced
with
.Tn NUL
bytes (or with spaces if a block oriented conversion value was
specified) and processed as a normal input buffer.
If the
.Cm sync
conversion is not specified, the input block is omitted from the output.
On input files which are not tapes or pipes, the file offset
will be positioned past the block in which the error occurred using
.Xr lseek 2 .
.It Cm notrunc
Do not truncate the output file.
This will preserve any blocks in the output file not explicitly written
by
.Nm .
The
.Cm notrunc
value is not supported for tapes.
.It Cm osync
Pad the final output block to the full output block size.
If the input file is not a multiple of the output block size
after conversion, this conversion forces the final output block
to be the same size as preceding blocks for use on devices that require
regularly sized blocks to be written.
This option is incompatible with use of the
.Cm bs= Ns Ar n
block size specification.
.It Cm sparse
If one or more non-final output blocks would consist solely of
.Dv NUL
bytes, try to seek the output file by the required space instead of
filling them with
.Dv NUL Ns s .
This results in a sparse file on some file systems.
.It Cm swab
Swap every pair of input bytes.
If an input buffer has an odd number of bytes, the last byte will be
ignored during swapping.
.It Cm sync
Pad every input block to the input buffer size.
Spaces are used for pad bytes if a block oriented conversion value is
specified, otherwise
.Tn NUL
bytes are used.
.It Cm ucase
Transform lowercase characters into uppercase characters.
.It Cm unblock
Treats the input as a sequence of fixed length records independent of input
and output block boundaries.
The length of the input records is specified by the
.Cm cbs
operand.
Any trailing space characters are discarded and a newline character is
appended.
.El
.El
.Pp
Where sizes are specified, a decimal number of bytes is expected.
Two or more numbers may be separated by an
.Dq x
to indicate a product.
Each number may have one of the following optional suffixes:
.Bl -tag -width 3n -offset indent -compact
.It b
Block; multiply by 512
.It k
Kibi; multiply by 1024 (1 KiB)
.It m
Mebi; multiply by 1048576 (1 MiB)
.It g
Gibi; multiply by 1073741824 (1 GiB)
.It t
Tebi; multiply by 1099511627776 (1 TiB)
.It w
Word; multiply by the number of bytes in an integer
.El
.Pp
When finished,
.Nm
displays the number of complete and partial input and output blocks,
truncated input records and odd-length byte-swapping blocks to the
standard error output.
A partial input block is one where less than the input block size
was read.
A partial output block is one where less than the output block size
was written.
Partial output blocks to tape devices are considered fatal errors.
Otherwise, the rest of the block will be written.
Partial output blocks to character devices will produce a warning message.
A truncated input block is one where a variable length record oriented
conversion value was specified and the input line was too long to
fit in the conversion record or was not newline terminated.
.Pp
Normally, data resulting from input or conversion or both are aggregated
into output blocks of the specified size.
After the end of input is reached, any remaining output is written as
a block.
This means that the final output block may be shorter than the output
block size.
.Pp
If
.Nm
receives a
.Dv SIGINFO
signal
(see the
.Ic status
argument for
.Xr stty 1 ) ,
the current input and output block counts will
be written to the standard error output
in the same format as the standard completion message.
If
.Nm
receives a
.Dv SIGINT
signal, the current input and output block counts will
be written to the standard error output
in the same format as the standard completion message and
.Nm
will exit.
.Sh INPUT AND OUTPUT FLAGS
There are flags valid for input only, for output only, or for either.
.Pp
The flags that apply to both input and output are:
.Bl -tag -width directory
.It Cm alt_io
Use Alternative I/O.
.It Cm async
Use
.Dv SIGIO
signaling for I/O.
.It Cm cloexec
Set the close-on-exec flag.
.It Cm direct
Directly access the data, skipping any caches.
.It Cm directory
Not available for
.Nm .
.It Cm exlock
Atomically obtain an exclusive lock.
.It Cm noctty
Do not consider the file as a potential controlling tty.
.It Cm nofollow
Do not follow symbolic links.
.It Cm nonblock
Do not block on open or I/O requests.
.It Cm nosigpipe
Return
.Er EPIPE
instead of raising
.Dv SIGPIPE .
.It Cm shlock
Atomically obtain a shared lock.
.It Cm sync
All I/O will be performed with full synchronization.
.El
.Pp
The flags that apply to only input are:
.Bl -tag -width directory
.It Cm rdonly
Set the read-only flag.
.It Cm rdwr
Set the read and write flags.
.It Cm rsync
Enable read synchronization, if the
.Cm sync
option is also set.
.El
.Pp
The flags that apply to only output are:
.Bl -tag -width directory
.It Cm append
Append to the output by default.
.It Cm creat
Create the output file.
.It Cm dsync
Wait for all data to be synchronously written.
.It Cm excl
Ensure that output is to a new file.
.It Cm trunc
Truncate the output file before writing.
.It Cm wronly
Set the write-only flag.
.El
See
.Xr open 2
and
.Xr ioctl 2
for more details.
.Sh EXIT STATUS
.Ex -std dd
.Sh EXAMPLES
To print summary information in human-readable form:
.Pp
.Dl dd if=/dev/zero of=/dev/null count=1 msgfmt=human
.Pp
To customize the information summary output and print it through
.Xr unvis 3 :
.Bd -literal -offset indent
dd if=/dev/zero of=/dev/null count=1 \e
     msgfmt='speed:%E, in %s seconds\en' 2>&1 | unvis
.Ed
.Sh SEE ALSO
.Xr cp 1 ,
.Xr mt 1 ,
.Xr tr 1
.Sh STANDARDS
The
.Nm
utility is expected to be a superset of the
.St -p1003.2
standard.
The
.Cm files
and
.Cm msgfmt
operands and the
.Cm ascii ,
.Cm ebcdic ,
.Cm ibm ,
.Cm oldascii ,
.Cm oldebcdic
and
.Cm oldibm
values are extensions to the
.Tn POSIX
standard.
.Sh HISTORY
A
.Nm
utility appeared in
.At v5 .