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35 .\" @(#)dd.1 8.2 (Berkeley) 1/13/94
36 .\" $Id: dd.1,v 1.7 1998/05/06 06:51:35 charnier Exp $
43 .Nd convert and copy a file
50 utility copies the standard input to the standard output.
51 Input data is read and written in 512-byte blocks.
52 If input reads are short, input from multiple reads are aggregated
53 to form the output block.
56 displays the number of complete and partial input and output blocks
57 and truncated input records to the standard error output.
59 The following operands are available:
60 .Bl -tag -width of=file
62 Set both input and output block size to
64 bytes, superseding the
69 If no conversion values other than
74 are specified, then each input block is copied to the output as a
75 single block without any aggregation of short blocks.
77 Set the conversion record size to
80 The conversion record size is required by the record oriented conversion
89 input files before terminating.
90 This operand is only applicable when the input device is a tape.
92 Set the input block size to
94 bytes instead of the default 512.
98 instead of the standard input.
100 Set the output block size to
102 bytes instead of the default 512.
103 .It Cm of= Ns Ar file
106 instead of the standard output.
107 Any regular output file is truncated unless the
109 conversion value is specified.
110 If an initial portion of the output file is skipped (see the
113 the output file is truncated at that point.
117 blocks from the beginning of the output before copying.
118 On non-tape devices, an
121 Otherwise, existing blocks are read and the data discarded.
122 If the user does not have read permission for the tape, it is positioned
126 If the seek operation is past the end of file, space from the current
127 end of file to the specified offset is filled with blocks of
133 blocks from the beginning of the input before copying.
134 On input which supports seeks, an
137 Otherwise, input data is read and discarded.
138 For pipes, the correct number of bytes is read.
139 For all other devices, the correct number of blocks is read without
140 distinguishing between a partial or complete block being read.
143 .Ns Cm value Ns Op \&, Cm value \&...
147 is one of the symbols from the following list.
148 .Bl -tag -width unblock
149 .It Cm ascii , oldascii
152 value except that characters are translated from
157 records are converted.
163 There are two conversion maps for
167 specifies the recommended one which is compatible with System V.
170 specifies the one used in historic
172 and pre-4.3BSD-reno systems.
174 Treats the input as a sequence of newline or end-of-file terminated variable
175 length records independent of input and output block boundaries.
176 Any trailing newline character is discarded.
177 Each input record is converted to a fixed length output record where the
178 length is specified by the
181 Input records shorter than the conversion record size are padded with spaces.
182 Input records longer than the conversion record size are truncated.
183 The number of truncated input records, if any, are reported to the standard
184 error output at the completion of the copy.
185 .It Cm ebcdic , ibm , oldebcdic , oldibm
188 value except that characters are translated from
193 records are converted.
199 There are four conversion maps for
203 specifies the recommended one which is compatible with
207 is a slightly different mapping, which is compatible with the
215 are maps used in historic
217 and pre-4.3BSD-reno systems.
219 Transform uppercase characters into lowercase characters.
221 Do not stop processing on an input error.
222 When an input error occurs, a diagnostic message followed by the current
223 input and output block counts will be written to the standard error output
224 in the same format as the standard completion message.
227 conversion is also specified, any missing input data will be replaced
230 bytes (or with spaces if a block oriented conversion value was
231 specified) and processed as a normal input buffer.
234 conversion is not specified, the input block is omitted from the output.
235 On input files which are not tapes or pipes, the file offset
236 will be positioned past the block in which the error occurred using
239 Do not truncate the output file.
240 This will preserve any blocks in the output file not explicitly written
245 value is not supported for tapes.
247 Pad the final output block to the full output block size.
248 If the input file is not a multiple of the output block size
249 after conversion, this conversion forces the final output block
250 to be the same size as preceding blocks for use on devices that require
251 regularly sized blocks to be written.
252 This option is incompatible with use of the
254 block size specification.
256 If one or more output blocks would consist solely of
258 bytes, try to seek the output file by the required space instead of
261 resulting in a sparse file.
263 Swap every pair of input bytes.
264 If an input buffer has an odd number of bytes, the last byte will be
265 ignored during swapping.
267 Pad every input block to the input buffer size.
268 Spaces are used for pad bytes if a block oriented conversion value is
273 Transform lowercase characters into uppercase characters.
275 Treats the input as a sequence of fixed length records independent of input
276 and output block boundaries.
277 The length of the input records is specified by the
280 Any trailing space characters are discarded and a newline character is
285 Where sizes are specified, a decimal number of bytes is expected.
286 If the number ends with a ``b'', ``k'', ``m'' or ``w'', the number
287 is multiplied by 512, 1024 (1K), 1048576 (1M) or the number of bytes
288 in an integer, respectively.
289 Two or more numbers may be separated by an ``x'' to indicate a product.
293 displays the number of complete and partial input and output blocks,
294 truncated input records and odd-length byte-swapping blocks to the
295 standard error output.
296 A partial input block is one where less than the input block size
298 A partial output block is one where less than the output block size
300 Partial output blocks to tape devices are considered fatal errors.
301 Otherwise, the rest of the block will be written.
302 Partial output blocks to character devices will produce a warning message.
303 A truncated input block is one where a variable length record oriented
304 conversion value was specified and the input line was too long to
305 fit in the conversion record or was not newline terminated.
307 Normally, data resulting from input or conversion or both are aggregated
308 into output blocks of the specified size.
309 After the end of input is reached, any remaining output is written as
311 This means that the final output block may be shorter than the output
318 (see the ``status'' argument for
320 signal, the current input and output block counts will
321 be written to the standard error output
322 in the same format as the standard completion message.
327 signal, the current input and output block counts will
328 be written to the standard error output
329 in the same format as the standard completion message and
335 utility exits 0 on success or >0 if an error occurred.
343 utility is expected to be a superset of the
356 values are extensions to the