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--- old/usr/src/man/man1m/dd.1m
+++ new/usr/src/man/man1m/dd.1m
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49 49 .TH DD 1M "Dec 12, 2014"
50 50 .SH NAME
51 51 dd \- convert and copy a file
52 52 .SH SYNOPSIS
53 53 .LP
54 54 .nf
55 55 \fB/usr/bin/dd\fR [\fIoperand=value\fR]...
56 56 .fi
57 57
58 58 .SH DESCRIPTION
59 59 .LP
60 60 The \fBdd\fR utility copies the specified input file to the specified output
61 61 with possible conversions. The standard input and output are used by default.
62 62 The input and output block sizes may be specified to take advantage of raw
63 63 physical I/O. Sizes are specified in bytes; a number may end with \fBk\fR,
64 64 \fBb\fR, or \fBw\fR to specify multiplication by 1024, 512, or 2, respectively.
65 65 Numbers may also be separated by \fBx\fR to indicate multiplication.
66 66 .sp
67 67 .LP
68 68 The \fBdd\fR utility reads the input one block at a time, using the specified
69 69 input block size. \fBdd\fR then processes the block of data actually returned,
70 70 which could be smaller than the requested block size. \fBdd\fR applies any
71 71 conversions that have been specified and writes the resulting data to the
72 72 output in blocks of the specified output block size.
73 73 .sp
74 74 .LP
75 75 \fBcbs\fR is used only if \fBascii\fR, \fBasciib\fR, \fBunblock\fR,
76 76 \fBebcdic\fR, \fBebcdicb\fR, \fBibm\fR, \fBibmb\fR, or \fBblock\fR conversion
77 77 is specified. In the first two cases, \fBcbs\fR characters are copied into the
78 78 conversion buffer, any specified character mapping is done, trailing blanks are
79 79 trimmed, and a \fBNEWLINE\fR is added before sending the line to output. In the
80 80 last three cases, characters up to \fBNEWLINE\fR are read into the conversion
81 81 buffer and blanks are added to make up an output record of size \fBcbs\fR.
82 82 \fBASCII\fR files are presumed to contain \fBNEWLINE\fR characters. If
83 83 \fBcbs\fR is unspecified or \fB0\fR, the \fBascii\fR, \fBasciib\fR,
84 84 \fBebcdic\fR, \fBebcdicb\fR, \fBibm\fR, and \fBibmb\fR options convert the
85 85 character set without changing the input file's block structure. The
86 86 \fBunblock\fR and \fBblock\fR options become a simple file copy.
87 87 .sp
88 88 .LP
89 89 After completion, \fBdd\fR reports the number of whole and partial input and
90 90 output blocks.
91 91 .SH OPERANDS
92 92 .LP
93 93 The following operands are supported:
94 94 .sp
95 95 .ne 2
96 96 .na
97 97 \fB\fBif=\fR\fIfile\fR\fR
98 98 .ad
99 99 .sp .6
100 100 .RS 4n
101 101 Specifies the input path. Standard input is the default.
102 102 .RE
103 103
104 104 .sp
105 105 .ne 2
106 106 .na
107 107 \fB\fBof=\fR\fIfile\fR\fR
108 108 .ad
109 109 .sp .6
110 110 .RS 4n
111 111 Specifies the output path. Standard output is the default. If the
112 112 \fBseek=\fR\fBexpr\fR conversion is not also specified, the output file will be
113 113 truncated before the copy begins, unless \fBconv=notrunc\fR is specified. If
114 114 \fBseek=\fR\fBexpr\fR is specified, but \fBconv=notrunc\fR is not, the effect
115 115 of the copy will be to preserve the blocks in the output file over which
116 116 \fBdd\fR seeks, but no other portion of the output file will be preserved. (If
117 117 the size of the seek plus the size of the input file is less than the previous
118 118 size of the output file, the output file is shortened by the copy.)
119 119 .RE
120 120
121 121 .sp
122 122 .ne 2
123 123 .na
124 124 \fB\fBibs=\fR\fIn\fR\fR
125 125 .ad
126 126 .sp .6
127 127 .RS 4n
128 128 Specifies the input block size in \fIn\fR bytes (default is \fB512\fR).
129 129 .RE
130 130
131 131 .sp
132 132 .ne 2
133 133 .na
134 134 \fB\fBobs=\fR\fIn\fR\fR
135 135 .ad
136 136 .sp .6
137 137 .RS 4n
138 138 Specifies the output block size in \fIn\fR bytes (default is \fB512\fR).
139 139 .RE
140 140
141 141 .sp
142 142 .ne 2
143 143 .na
144 144 \fB\fBbs=\fR\fIn\fR\fR
145 145 .ad
146 146 .sp .6
147 147 .RS 4n
148 148 Sets both input and output block sizes to \fIn\fR bytes, superseding \fBibs=\fR
149 149 and \fBobs=\fR. If no conversion other than \fBsync\fR,\fB noerror\fR, and
150 150 \fBnotrunc\fR is specified, each input block is copied to the output as a
151 151 single block without aggregating short blocks.
152 152 .RE
153 153
154 154 .sp
155 155 .ne 2
156 156 .na
157 157 \fB\fBcbs=\fR\fIn\fR\fR
158 158 .ad
159 159 .sp .6
160 160 .RS 4n
161 161 Specifies the conversion block size for \fBblock\fR and \fBunblock\fR in bytes
162 162 by \fIn\fR (default is \fB0\fR). If \fBcbs=\fR is omitted or given a value of
163 163 \fB0\fR, using \fBblock\fR or \fBunblock\fR produces unspecified results.
164 164 .sp
165 165 This option is used only if \fBASCII\fR or \fBEBCDIC\fR conversion is
166 166 specified. For the \fBascii\fR and \fBasciib\fR operands, the input is handled
167 167 as described for the \fBunblock\fR operand except that characters are converted
168 168 to \fBASCII\fR before the trailing \fBSPACE\fR characters are deleted. For the
169 169 \fBebcdic\fR, \fBebcdicb\fR, \fBibm\fR, and \fBibmb\fR operands, the input is
170 170 handled as described for the \fBblock\fR operand except that the characters are
171 171 converted to \fBEBCDIC\fR or IBM \fBEBCDIC\fR after the trailing \fBSPACE\fR
172 172 characters are added.
173 173 .RE
174 174
175 175 .sp
176 176 .ne 2
177 177 .na
178 178 \fB\fBfiles=\fR\fIn\fR\fR
179 179 .ad
180 180 .sp .6
181 181 .RS 4n
182 182 Copies and concatenates \fIn\fR input files before terminating (makes sense
183 183 only where input is a magnetic tape or similar device).
184 184 .RE
185 185
186 186 .sp
187 187 .ne 2
188 188 .na
189 189 \fB\fBskip=\fR\fIn\fR\fR
190 190 .ad
191 191 .sp .6
192 192 .RS 4n
193 193 Skips \fIn\fR input blocks (using the specified input block size) before
194 194 starting to copy. On seekable files, the implementation reads the blocks or
195 195 seeks past them. On non-seekable files, the blocks are read and the data is
196 196 discarded.
197 197 .RE
198 198
199 199 .sp
200 200 .ne 2
201 201 .na
202 202 \fB\fBiseek=\fR\fIn\fR\fR
203 203 .ad
204 204 .sp .6
205 205 .RS 4n
206 206 Seeks \fIn\fR blocks from beginning of input file before copying (appropriate
207 207 for disk files, where \fBskip\fR can be incredibly slow).
208 208 .RE
209 209
210 210 .sp
211 211 .ne 2
212 212 .na
213 213 \fB\fBoseek=\fR\fIn\fR\fR
214 214 .ad
215 215 .sp .6
216 216 .RS 4n
217 217 Seeks \fIn\fR blocks from beginning of output file before copying.
218 218 .RE
219 219
220 220 .sp
221 221 .ne 2
222 222 .na
223 223 \fB\fBseek=\fR\fIn\fR\fR
224 224 .ad
225 225 .sp .6
226 226 .RS 4n
227 227 Skips \fIn\fR blocks (using the specified output block size) from beginning of
228 228 output file before copying. On non-seekable files, existing blocks are read and
229 229 space from the current end-of-file to the specified offset, if any, is filled
230 230 with null bytes. On seekable files, the implementation seeks to the specified
231 231 offset or reads the blocks as described for non-seekable files.
232 232 .RE
233 233
234 234 .sp
235 235 .ne 2
236 236 .na
237 237 \fB\fBostride=\fR\fIn\fR\fR
238 238 .ad
239 239 .sp .6
240 240 .RS 4n
241 241 Writes every \fIn\fRth block (using the specified output block size) when
242 242 writing output. Skips \fIn\fR - 1 blocks after writing each record.
243 243 .RE
244 244
245 245 .sp
246 246 .ne 2
247 247 .na
248 248 \fB\fBistride=\fR\fIn\fR\fR
249 249 .ad
250 250 .sp .6
251 251 .RS 4n
252 252 Reads every \fIn\fRth block (using the specified input block size) when
253 253 reading input. Skips \fIn\fR - 1 blocks after reading each record.
254 254 .RE
255 255
256 256 .sp
257 257 .ne 2
258 258 .na
259 259 \fB\fBstride=\fR\fIn\fR\fR
260 260 .ad
261 261 .sp .6
262 262 .RS 4n
263 263 Reads every \fIn\fRth block (using the specified input block size) when
264 264 reading input. Skips \fIn\fR - 1 blocks after reading each record. Also
265 265 writes every \fIn\fRth block (using the specified output block size) when
266 266 writing output. Skips \fIn\fR - 1 blocks after writing each record.
267 267 .RE
268 268
269 269 .sp
270 270 .ne 2
271 271 .na
272 272 \fB\fBcount=\fR\fIn\fR\fR
273 273 .ad
274 274 .sp .6
275 275 .RS 4n
276 276 Copies only \fIn\fR input blocks.
277 277 .RE
278 278
279 279 .sp
280 280 .ne 2
281 281 .na
282 282 \fB\fBconv=\fR\fIvalue\fR[\fB,\fR\fIvalue\fR.\|.\|.\|]\fR
283 283 .ad
284 284 .sp .6
285 285 .RS 4n
286 286 Where \fIvalue\fRs are comma-separated symbols from the following list:
287 287 .sp
288 288 .ne 2
289 289 .na
290 290 \fB\fBascii\fR\fR
291 291 .ad
292 292 .RS 11n
293 293 Converts \fBEBCDIC\fR to \fBASCII\fR.
294 294 .RE
295 295
296 296 .sp
297 297 .ne 2
298 298 .na
299 299 \fB\fBasciib\fR\fR
300 300 .ad
301 301 .RS 11n
302 302 Converts \fBEBCDIC\fR to \fBASCII\fR using \fBBSD\fR-compatible character
303 303 translations.
304 304 .RE
305 305
306 306 .sp
307 307 .ne 2
308 308 .na
309 309 \fB\fBebcdic\fR\fR
310 310 .ad
311 311 .RS 11n
312 312 Converts \fBASCII\fR to \fBEBCDIC\fR. If converting fixed-length \fBASCII\fR
313 313 records without NEWLINEs, sets up a pipeline with \fBdd conv=unblock\fR
314 314 beforehand.
315 315 .RE
316 316
317 317 .sp
318 318 .ne 2
319 319 .na
320 320 \fB\fBebcdicb\fR\fR
321 321 .ad
322 322 .RS 11n
323 323 Converts \fBASCII\fR to \fBEBCDIC\fR using \fBBSD\fR-compatible character
324 324 translations. If converting fixed-length \fBASCII\fR records without
325 325 \fBNEWLINE\fRs, sets up a pipeline with \fBdd conv=unblock\fR beforehand.
326 326 .RE
327 327
328 328 .sp
329 329 .ne 2
330 330 .na
331 331 \fB\fBibm\fR\fR
332 332 .ad
333 333 .RS 11n
334 334 Slightly different map of \fBASCII\fR to \fBEBCDIC\fR. If converting
335 335 fixed-length \fBASCII\fR records without \fBNEWLINE\fRs, sets up a pipeline
336 336 with \fBdd conv=unblock\fR beforehand.
337 337 .RE
338 338
339 339 .sp
340 340 .ne 2
341 341 .na
342 342 \fB\fBibmb\fR\fR
343 343 .ad
344 344 .RS 11n
345 345 Slightly different map of \fBASCII\fR to \fBEBCDIC\fR using
346 346 \fBBSD\fR-compatible character translations. If converting fixed-length
347 347 \fBASCII\fR records without \fBNEWLINE\fRs, sets up a pipeline with \fBdd
348 348 conv=unblock\fR beforehand.
349 349 .RE
350 350
351 351 The \fBascii\fR (or \fBasciib\fR), \fBebcdic\fR (or \fBebcdicb\fR), and
352 352 \fBibm\fR (or \fBibmb\fR) values are mutually exclusive.
353 353 .sp
354 354 .ne 2
355 355 .na
356 356 \fB\fBblock\fR\fR
357 357 .ad
358 358 .RS 11n
359 359 Treats the input as a sequence of \fBNEWLINE\fR-terminated or
360 360 \fBEOF\fR-terminated variable-length records independent of the input block
361 361 boundaries. Each record is converted to a record with a fixed length specified
362 362 by the conversion block size. Any \fBNEWLINE\fR character is removed from the
363 363 input line. \fBSPACE\fR characters are appended to lines that are shorter than
364 364 their conversion block size to fill the block. Lines that are longer than the
365 365 conversion block size are truncated to the largest number of characters that
366 366 will fit into that size. The number of truncated lines is reported.
367 367 .RE
368 368
369 369 .sp
370 370 .ne 2
371 371 .na
372 372 \fB\fBunblock\fR\fR
373 373 .ad
374 374 .RS 11n
375 375 Converts fixed-length records to variable length. Reads a number of bytes equal
376 376 to the conversion block size (or the number of bytes remaining in the input, if
377 377 less than the conversion block size), delete all trailing \fBSPACE\fR
378 378 characters, and append a \fBNEWLINE\fR character.
379 379 .RE
380 380
381 381 The \fBblock\fR and \fBunblock\fR values are mutually exclusive.
382 382 .sp
383 383 .ne 2
384 384 .na
385 385 \fB\fBlcase\fR\fR
386 386 .ad
387 387 .RS 9n
388 388 Maps upper-case characters specified by the \fBLC_CTYPE\fR keyword
389 389 \fBtolower\fR to the corresponding lower-case character. Characters for which
390 390 no mapping is specified are not modified by this conversion.
391 391 .RE
392 392
393 393 .sp
394 394 .ne 2
395 395 .na
396 396 \fB\fBucase\fR\fR
397 397 .ad
398 398 .RS 9n
399 399 Maps lower-case characters specified by the \fBLC_CTYPE\fR keyword
400 400 \fBtoupper\fR to the corresponding upper-case character. Characters for which
401 401 no mapping is specified are not modified by this conversion.
402 402 .RE
403 403
404 404 The \fBlcase\fR and \fBucase\fR symbols are mutually exclusive.
405 405 .sp
406 406 .ne 2
407 407 .na
408 408 \fB\fBswab\fR\fR
409 409 .ad
410 410 .RS 11n
411 411 Swaps every pair of input bytes. If the current input record is an odd number
412 412 of bytes, the last byte in the input record is ignored.
413 413 .RE
414 414
415 415 .sp
416 416 .ne 2
417 417 .na
418 418 \fB\fBnoerror\fR\fR
419 419 .ad
420 420 .RS 11n
421 421 Does not stop processing on an input error. When an input error occurs, a
422 422 diagnostic message is written on standard error, followed by the current input
423 423 and output block counts in the same format as used at completion. If the
424 424 \fBsync\fR conversion is specified, the missing input is replaced with null
425 425 bytes and processed normally. Otherwise, the input block will be omitted from
426 426 the output.
427 427 .RE
428 428
429 429 .sp
430 430 .ne 2
431 431 .na
432 432 \fB\fBnotrunc\fR\fR
433 433 .ad
434 434 .RS 11n
435 435 Does not truncate the output file. Preserves blocks in the output file not
436 436 explicitly written by this invocation of \fBdd\fR. (See also the preceding
437 437 \fBof=\fR\fIfile\fR operand.)
438 438 .RE
439 439
440 440 .sp
|
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440 lines elided |
↑ open up ↑ |
441 441 .ne 2
442 442 .na
443 443 \fB\fBsync\fR\fR
444 444 .ad
445 445 .RS 11n
446 446 Pads every input block to the size of the \fBibs=\fR buffer, appending null
447 447 bytes. (If either \fBblock\fR or \fBunblock\fR is also specified, appends
448 448 \fBSPACE\fR characters, rather than null bytes.)
449 449 .RE
450 450
451 -.RE
452 -
453 451 .sp
454 452 .ne 2
455 453 .na
456 454 \fB\fBoflag=\fR\fIvalue\fR[\fB,\fR\fIvalue\fR.\|.\|.\|]\fR
457 455 .ad
458 456 .sp .6
459 457 Where \fIvalue\fRs are comma-separated symbols from the following list which
460 458 affect the behavior of writing the output file:
461 459 .sp
462 460 .ne 2
463 461 .na
464 462 \fB\fBdsync\fR\fR
465 463 .ad
466 464 .RS 11n
467 465 The output file is opened with the \fBO_DSYNC\fR flag set. All data writes will
468 466 be synchronous. For more information on \fBO_DSYNC\fR see \fBfcntl.h\fR(3HEAD).
469 467 .RE
470 468
471 469 .sp
472 470 .ne 2
473 471 .na
474 472 \fB\fBsync\fR\fR
475 473 .ad
476 474 .RS 11n
477 475 The output file is opened with the \fBO_SYNC\fR flag set. All data and metadata
478 476 writes will be synchronous. For more information on \fBO_SYNC\fR see
479 477 \fBfcntl.h\fR(3HEAD).
480 478 .RE
481 479
482 480 .sp
483 481 .LP
484 482 If operands other than \fBconv=\fR and \fBoflag=\fR are specified more than once,
485 483 the last specified \fBoperand=\fR\fIvalue\fR is used.
486 484 .sp
487 485 .LP
488 486 For the \fBbs=\fR, \fBcbs=\fR, \fBibs=\fR, and \fBobs=\fR operands, the
489 487 application must supply an expression specifying a size in bytes. The
490 488 expression, \fBexpr\fR, can be:
491 489 .RS +4
492 490 .TP
493 491 1.
494 492 a positive decimal number
495 493 .RE
496 494 .RS +4
497 495 .TP
498 496 2.
499 497 a positive decimal number followed by \fBk\fR, specifying multiplication by
500 498 1024
501 499 .RE
502 500 .RS +4
503 501 .TP
504 502 3.
505 503 a positive decimal number followed by \fBM\fR, specifying multiplication by
506 504 1024*1024
507 505 .RE
508 506 .RS +4
509 507 .TP
510 508 4.
511 509 a positive decimal number followed by \fBG\fR, specifying multiplication by
512 510 1024*1024*1024
513 511 .RE
514 512 .RS +4
515 513 .TP
516 514 5.
517 515 a positive decimal number followed by \fBT\fR, specifying multiplication by
518 516 1024*1024*1024*1024
519 517 .RE
520 518 .RS +4
521 519 .TP
522 520 6.
523 521 a positive decimal number followed by \fBP\fR, specifying multiplication by
524 522 1024*1024*1024*1024*1024
525 523 .RE
526 524 .RS +4
527 525 .TP
528 526 7.
529 527 a positive decimal number followed by \fBE\fR, specifying multiplication by
530 528 1024*1024*1024*1024*1024*1024
531 529 .RE
532 530 .RS +4
533 531 .TP
534 532 8.
535 533 a positive decimal number followed by \fBZ\fR, specifying multiplication by
536 534 1024*1024*1024*1024*1024*1024*1024
537 535 .RE
538 536 .RS +4
539 537 .TP
540 538 9.
541 539 a positive decimal number followed by \fBb\fR, specifying multiplication by
542 540 512
543 541 .RE
544 542 .RS +4
545 543 .TP
546 544 10.
547 545 two or more positive decimal numbers (with or without \fBk\fR or \fBb\fR)
548 546 separated by \fBx\fR, specifying the product of the indicated values.
549 547 .RE
550 548 .sp
551 549 .LP
552 550 All of the operands will be processed before any input is read.
553 551 .SH SIGNALS
554 552 .LP
555 553 When \fBdd\fR receives either SIGINFO or SIGUSR1, \fBdd\fR will emit the current
556 554 input and output block counts, total bytes written, total time elapsed, and the
557 555 number of bytes per second to standard error. This is the same information
558 556 format that \fBdd\fR emits when it successfully completes. Users may send
559 557 SIGINFO via their terminal. The default character is ^T, see \fBstty\fR(1) for
560 558 more information.
561 559 .sp
562 560 .LP
563 561 For \fBSIGINT\fR, \fBdd\fR writes status information to standard error before
564 562 exiting. \fBdd\fR takes the standard action for all other signals.
565 563
566 564 .SH USAGE
567 565 .LP
568 566 See \fBlargefile\fR(5) for the description of the behavior of \fBdd\fR when
569 567 encountering files greater than or equal to 2 Gbyte ( 2^31 bytes).
570 568 .SH EXAMPLES
571 569 .LP
572 570 \fBExample 1 \fRCopying from one tape drive to another
573 571 .sp
574 572 .LP
575 573 The following example copies from tape drive \fB0\fR to tape drive \fB1\fR,
576 574 using a common historical device naming convention.
577 575
578 576 .sp
579 577 .in +2
580 578 .nf
581 579 example% \fBdd if=/dev/rmt/0h of=/dev/rmt/1h\fR
582 580 .fi
583 581 .in -2
584 582 .sp
585 583
586 584 .LP
587 585 \fBExample 2 \fRStripping the first 10 bytes from standard input
588 586 .sp
589 587 .LP
590 588 The following example strips the first 10 bytes from standard input:
591 589
592 590 .sp
593 591 .in +2
594 592 .nf
595 593 example% \fBdd ibs=10 skip=1\fR
596 594 .fi
597 595 .in -2
598 596 .sp
599 597
600 598 .LP
601 599 \fBExample 3 \fRReading a tape into an ASCII file
602 600 .sp
603 601 .LP
604 602 This example reads an \fBEBCDIC\fR tape blocked ten 80-byte \fBEBCDIC\fR card
605 603 images per block into the \fBASCII\fR file \fBx\fR:
606 604
607 605 .sp
608 606 .in +2
609 607 .nf
610 608 example% \fBdd if=/dev/tape of=x ibs=800 cbs=80 conv=ascii,lcase\fR
611 609 .fi
612 610 .in -2
613 611 .sp
614 612
615 613 .LP
616 614 \fBExample 4 \fRUsing conv=sync to write to tape
617 615 .sp
618 616 .LP
619 617 The following example uses \fBconv=sync\fR when writing to a tape:
620 618
621 619 .sp
622 620 .in +2
623 621 .nf
624 622 example% \fBtar cvf - . | compress | dd obs=1024k of=/dev/rmt/0 conv=sync\fR
625 623 .fi
626 624 .in -2
627 625 .sp
628 626
629 627 .SH ENVIRONMENT VARIABLES
630 628 .LP
631 629 See \fBenviron\fR(5) for descriptions of the following environment variables
632 630 that affect the execution of \fBdd\fR: \fBLANG\fR, \fBLC_ALL\fR,
633 631 \fBLC_CTYPE\fR, \fBLC_MESSAGES\fR, and \fBNLSPATH\fR.
634 632 .SH EXIT STATUS
635 633 .LP
636 634 The following exit values are returned:
637 635 .sp
638 636 .ne 2
639 637 .na
640 638 \fB\fB0\fR\fR
641 639 .ad
642 640 .RS 6n
643 641 The input file was copied successfully.
644 642 .RE
645 643
646 644 .sp
647 645 .ne 2
648 646 .na
649 647 \fB\fB>0\fR\fR
650 648 .ad
651 649 .RS 6n
652 650 An error occurred.
653 651 .RE
654 652
655 653 .sp
656 654 .LP
657 655 If an input error is detected and the \fBnoerror\fR conversion has not been
658 656 specified, any partial output block will be written to the output file, a
659 657 diagnostic message will be written, and the copy operation will be
660 658 discontinued. If some other error is detected, a diagnostic message will be
661 659 written and the copy operation will be discontinued.
662 660 .SH ATTRIBUTES
663 661 .LP
664 662 See \fBattributes\fR(5) for descriptions of the following attributes:
665 663 .sp
666 664
667 665 .sp
668 666 .TS
669 667 box;
670 668 c | c
671 669 l | l .
672 670 ATTRIBUTE TYPE ATTRIBUTE VALUE
673 671 _
674 672 Interface Stability Standard
675 673 .TE
676 674
677 675 .SH SEE ALSO
678 676 .LP
679 677 \fBcp\fR(1), \fBsed\fR(1), \fBtr\fR(1), \fBfcntl.h\fR(3HEAD),
680 678 \fBattributes\fR(5), \fBenviron\fR(5), \fBlargefile\fR(5), \fBstandards\fR(5)
681 679 .SH DIAGNOSTICS
682 680 .ne 2
683 681 .na
684 682 \fB\fBf+p records in(out)\fR\fR
685 683 .ad
686 684 .RS 23n
687 685 numbers of full and partial blocks read(written)
688 686 .RE
689 687
690 688 .SH NOTES
691 689 .LP
692 690 Do not use \fBdd\fR to copy files between file systems having different block
693 691 sizes.
694 692 .sp
695 693 .LP
696 694 Using a blocked device to copy a file will result in extra nulls being added
697 695 to the file to pad the final block to the block boundary.
698 696 .sp
699 697 .LP
700 698 When \fBdd\fR reads from a pipe, using the \fBibs=X\fR and \fBobs=Y\fR
701 699 operands, the output will always be blocked in chunks of size Y. When
702 700 \fBbs=Z\fR is used, the output blocks will be whatever was available to be read
703 701 from the pipe at the time.
704 702 .sp
705 703 .LP
706 704 When using \fBdd\fR to copy files to a tape device, the file size must be a
707 705 multiple of the device sector size (for example, 512 Kbyte). To copy files of
708 706 arbitrary size to a tape device, use \fBtar\fR(1) or \fBcpio\fR(1).
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