1.\" Copyright (c) 1990, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" Keith Muller of the University of California, San Diego. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by the University of 18.\" California, Berkeley and its contributors. 19.\" 4. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" @(#)dd.1 8.2 (Berkeley) 1/13/94 36.\" $FreeBSD$ 37.\" 38.Dd January 13, 1994 39.Dt DD 1 40.Os 41.Sh NAME 42.Nm dd 43.Nd convert and copy a file 44.Sh SYNOPSIS 45.Nm 46.Op operands ... 47.Sh DESCRIPTION 48The 49.Nm 50utility copies the standard input to the standard output. 51Input data is read and written in 512-byte blocks. 52If input reads are short, input from multiple reads are aggregated 53to form the output block. 54When finished, 55.Nm 56displays the number of complete and partial input and output blocks 57and truncated input records to the standard error output. 58.Pp 59The following operands are available: 60.Bl -tag -width of=file 61.It Cm bs= Ns Ar n 62Set both input and output block size to 63.Va n 64bytes, superseding the 65.Cm ibs 66and 67.Cm obs 68operands. 69If no conversion values other than 70.Cm noerror , 71.Cm notrunc 72or 73.Cm sync 74are specified, then each input block is copied to the output as a 75single block without any aggregation of short blocks. 76.It Cm cbs= Ns Ar n 77Set the conversion record size to 78.Va n 79bytes. 80The conversion record size is required by the record oriented conversion 81values. 82.It Cm count= Ns Ar n 83Copy only 84.Va n 85input blocks. 86.It Cm files= Ns Ar n 87Copy 88.Va n 89input files before terminating. 90This operand is only applicable when the input device is a tape. 91.It Cm ibs= Ns Ar n 92Set the input block size to 93.Va n 94bytes instead of the default 512. 95.It Cm if= Ns Ar file 96Read input from 97.Ar file 98instead of the standard input. 99.It Cm iseek= Ns Ar n 100Seek on the input file 101.Va n 102blocks. 103This is synonymous with 104.Cm skip= Ns Ar n . 105.It Cm obs= Ns Ar n 106Set the output block size to 107.Va n 108bytes instead of the default 512. 109.It Cm of= Ns Ar file 110Write output to 111.Ar file 112instead of the standard output. 113Any regular output file is truncated unless the 114.Cm notrunc 115conversion value is specified. 116If an initial portion of the output file is seeked past (see the 117.Cm oseek 118operand), 119the output file is truncated at that point. 120.It Cm oseek= Ns Ar n 121Seek on the output file 122.Va n 123blocks. 124This is synonymous with 125.Cm seek= Ns Ar n . 126.It Cm seek= Ns Ar n 127Seek 128.Va n 129blocks from the beginning of the output before copying. 130On non-tape devices, an 131.Xr lseek 2 132operation is used. 133Otherwise, existing blocks are read and the data discarded. 134If the user does not have read permission for the tape, it is positioned 135using the tape 136.Xr ioctl 2 137function calls. 138If the seek operation is past the end of file, space from the current 139end of file to the specified offset is filled with blocks of 140.Tn NUL 141bytes. 142.It Cm skip= Ns Ar n 143Skip 144.Va n 145blocks from the beginning of the input before copying. 146On input which supports seeks, an 147.Xr lseek 2 148operation is used. 149Otherwise, input data is read and discarded. 150For pipes, the correct number of bytes is read. 151For all other devices, the correct number of blocks is read without 152distinguishing between a partial or complete block being read. 153.It Xo 154.Cm conv= 155.Ns Cm value Ns Op \&, Cm value \&... 156.Xc 157Where 158.Cm value 159is one of the symbols from the following list. 160.Bl -tag -width unblock 161.It Cm ascii , oldascii 162The same as the 163.Cm unblock 164value except that characters are translated from 165.Tn EBCDIC 166to 167.Tn ASCII 168before the 169records are converted. 170(These values imply 171.Cm unblock 172if the operand 173.Cm cbs 174is also specified.) 175There are two conversion maps for 176.Tn ASCII . 177The value 178.Cm ascii 179specifies the recommended one which is compatible with System V. 180The value 181.Cm oldascii 182specifies the one used in historic 183.Tn AT&T 184and 185.No pre- Ns Bx 4.3 reno 186systems. 187.It Cm block 188Treats the input as a sequence of newline or end-of-file terminated variable 189length records independent of input and output block boundaries. 190Any trailing newline character is discarded. 191Each input record is converted to a fixed length output record where the 192length is specified by the 193.Cm cbs 194operand. 195Input records shorter than the conversion record size are padded with spaces. 196Input records longer than the conversion record size are truncated. 197The number of truncated input records, if any, are reported to the standard 198error output at the completion of the copy. 199.It Cm ebcdic , ibm , oldebcdic , oldibm 200The same as the 201.Cm block 202value except that characters are translated from 203.Tn ASCII 204to 205.Tn EBCDIC 206after the 207records are converted. 208(These values imply 209.Cm block 210if the operand 211.Cm cbs 212is also specified.) 213There are four conversion maps for 214.Tn EBCDIC . 215The value 216.Cm ebcdic 217specifies the recommended one which is compatible with 218.At V . 219The value 220.Cm ibm 221is a slightly different mapping, which is compatible with the 222.At V 223.Cm ibm 224value. 225The values 226.Cm oldebcdic 227and 228.Cm oldibm 229are maps used in historic 230.Tn AT&T 231and 232.No pre- Ns Bx 4.3 reno 233systems. 234.It Cm lcase 235Transform uppercase characters into lowercase characters. 236.It Cm noerror 237Do not stop processing on an input error. 238When an input error occurs, a diagnostic message followed by the current 239input and output block counts will be written to the standard error output 240in the same format as the standard completion message. 241If the 242.Cm sync 243conversion is also specified, any missing input data will be replaced 244with 245.Tn NUL 246bytes (or with spaces if a block oriented conversion value was 247specified) and processed as a normal input buffer. 248If the 249.Cm sync 250conversion is not specified, the input block is omitted from the output. 251On input files which are not tapes or pipes, the file offset 252will be positioned past the block in which the error occurred using 253.Xr lseek 2 . 254.It Cm notrunc 255Do not truncate the output file. 256This will preserve any blocks in the output file not explicitly written 257by 258.Nm . 259The 260.Cm notrunc 261value is not supported for tapes. 262.It Cm osync 263Pad the final output block to the full output block size. 264If the input file is not a multiple of the output block size 265after conversion, this conversion forces the final output block 266to be the same size as preceding blocks for use on devices that require 267regularly sized blocks to be written. 268This option is incompatible with use of the 269.Cm bs= Ns Ar n 270block size specification. 271.It Cm sparse 272If one or more output blocks would consist solely of 273.Tn NUL 274bytes, try to seek the output file by the required space instead of 275filling them with 276.Tn NULs , 277resulting in a sparse file. 278.It Cm swab 279Swap every pair of input bytes. 280If an input buffer has an odd number of bytes, the last byte will be 281ignored during swapping. 282.It Cm sync 283Pad every input block to the input buffer size. 284Spaces are used for pad bytes if a block oriented conversion value is 285specified, otherwise 286.Tn NUL 287bytes are used. 288.It Cm ucase 289Transform lowercase characters into uppercase characters. 290.It Cm unblock 291Treats the input as a sequence of fixed length records independent of input 292and output block boundaries. 293The length of the input records is specified by the 294.Cm cbs 295operand. 296Any trailing space characters are discarded and a newline character is 297appended. 298.El 299.El 300.Pp 301Where sizes are specified, a decimal, octal, or hexadecimal number of 302bytes is expected. 303If the number ends with a ``b'', ``k'', ``m'', ``g'', or ``w'', the 304number is multiplied by 512, 1024 (1K), 1048576 (1M), 1073741824 (1G) 305or the number of bytes in an integer, respectively. 306Two or more numbers may be separated by an ``x'' to indicate a product. 307.Pp 308When finished, 309.Nm 310displays the number of complete and partial input and output blocks, 311truncated input records and odd-length byte-swapping blocks to the 312standard error output. 313A partial input block is one where less than the input block size 314was read. 315A partial output block is one where less than the output block size 316was written. 317Partial output blocks to tape devices are considered fatal errors. 318Otherwise, the rest of the block will be written. 319Partial output blocks to character devices will produce a warning message. 320A truncated input block is one where a variable length record oriented 321conversion value was specified and the input line was too long to 322fit in the conversion record or was not newline terminated. 323.Pp 324Normally, data resulting from input or conversion or both are aggregated 325into output blocks of the specified size. 326After the end of input is reached, any remaining output is written as 327a block. 328This means that the final output block may be shorter than the output 329block size. 330.Pp 331If 332.Nm 333receives a 334.Dv SIGINFO 335(see the ``status'' argument for 336.Xr stty 1 ) 337signal, the current input and output block counts will 338be written to the standard error output 339in the same format as the standard completion message. 340If 341.Nm 342receives a 343.Dv SIGINT 344signal, the current input and output block counts will 345be written to the standard error output 346in the same format as the standard completion message and 347.Nm 348will exit. 349.Sh DIAGNOSTICS 350.Ex -std 351.Sh SEE ALSO 352.Xr cp 1 , 353.Xr mt 1 , 354.Xr tr 1 355.Sh STANDARDS 356The 357.Nm 358utility is expected to be a superset of the 359.St -p1003.2 360standard. 361The 362.Cm files 363operand and the 364.Cm ascii , 365.Cm ebcdic , 366.Cm ibm , 367.Cm oldascii , 368.Cm oldebcdic 369and 370.Cm oldibm 371values are extensions to the 372.Tn POSIX 373standard. 374