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 pre-4.3BSD-reno systems. 185.It Cm block 186Treats the input as a sequence of newline or end-of-file terminated variable 187length records independent of input and output block boundaries. 188Any trailing newline character is discarded. 189Each input record is converted to a fixed length output record where the 190length is specified by the 191.Cm cbs 192operand. 193Input records shorter than the conversion record size are padded with spaces. 194Input records longer than the conversion record size are truncated. 195The number of truncated input records, if any, are reported to the standard 196error output at the completion of the copy. 197.It Cm ebcdic , ibm , oldebcdic , oldibm 198The same as the 199.Cm block 200value except that characters are translated from 201.Tn ASCII 202to 203.Tn EBCDIC 204after the 205records are converted. 206(These values imply 207.Cm block 208if the operand 209.Cm cbs 210is also specified.) 211There are four conversion maps for 212.Tn EBCDIC . 213The value 214.Cm ebcdic 215specifies the recommended one which is compatible with 216.At V . 217The value 218.Cm ibm 219is a slightly different mapping, which is compatible with the 220.At V 221.Cm ibm 222value. 223The values 224.Cm oldebcdic 225and 226.Cm oldibm 227are maps used in historic 228.Tn AT&T 229and pre-4.3BSD-reno systems. 230.It Cm lcase 231Transform uppercase characters into lowercase characters. 232.It Cm noerror 233Do not stop processing on an input error. 234When an input error occurs, a diagnostic message followed by the current 235input and output block counts will be written to the standard error output 236in the same format as the standard completion message. 237If the 238.Cm sync 239conversion is also specified, any missing input data will be replaced 240with 241.Tn NUL 242bytes (or with spaces if a block oriented conversion value was 243specified) and processed as a normal input buffer. 244If the 245.Cm sync 246conversion is not specified, the input block is omitted from the output. 247On input files which are not tapes or pipes, the file offset 248will be positioned past the block in which the error occurred using 249.Xr lseek 2 . 250.It Cm notrunc 251Do not truncate the output file. 252This will preserve any blocks in the output file not explicitly written 253by 254.Nm . 255The 256.Cm notrunc 257value is not supported for tapes. 258.It Cm osync 259Pad the final output block to the full output block size. 260If the input file is not a multiple of the output block size 261after conversion, this conversion forces the final output block 262to be the same size as preceding blocks for use on devices that require 263regularly sized blocks to be written. 264This option is incompatible with use of the 265.Cm bs= Ns Ar n 266block size specification. 267.It Cm sparse 268If one or more output blocks would consist solely of 269.Tn NUL 270bytes, try to seek the output file by the required space instead of 271filling them with 272.Tn NULs , 273resulting in a sparse file. 274.It Cm swab 275Swap every pair of input bytes. 276If an input buffer has an odd number of bytes, the last byte will be 277ignored during swapping. 278.It Cm sync 279Pad every input block to the input buffer size. 280Spaces are used for pad bytes if a block oriented conversion value is 281specified, otherwise 282.Tn NUL 283bytes are used. 284.It Cm ucase 285Transform lowercase characters into uppercase characters. 286.It Cm unblock 287Treats the input as a sequence of fixed length records independent of input 288and output block boundaries. 289The length of the input records is specified by the 290.Cm cbs 291operand. 292Any trailing space characters are discarded and a newline character is 293appended. 294.El 295.El 296.Pp 297Where sizes are specified, a decimal, octal, or hexadecimal number of 298bytes is expected. 299If the number ends with a ``b'', ``k'', ``m'', ``g'', or ``w'', the 300number is multiplied by 512, 1024 (1K), 1048576 (1M), 1073741824 (1G) 301or the number of bytes in an integer, respectively. 302Two or more numbers may be separated by an ``x'' to indicate a product. 303.Pp 304When finished, 305.Nm 306displays the number of complete and partial input and output blocks, 307truncated input records and odd-length byte-swapping blocks to the 308standard error output. 309A partial input block is one where less than the input block size 310was read. 311A partial output block is one where less than the output block size 312was written. 313Partial output blocks to tape devices are considered fatal errors. 314Otherwise, the rest of the block will be written. 315Partial output blocks to character devices will produce a warning message. 316A truncated input block is one where a variable length record oriented 317conversion value was specified and the input line was too long to 318fit in the conversion record or was not newline terminated. 319.Pp 320Normally, data resulting from input or conversion or both are aggregated 321into output blocks of the specified size. 322After the end of input is reached, any remaining output is written as 323a block. 324This means that the final output block may be shorter than the output 325block size. 326.Pp 327If 328.Nm 329receives a 330.Dv SIGINFO 331(see the ``status'' argument for 332.Xr stty 1 ) 333signal, the current input and output block counts will 334be written to the standard error output 335in the same format as the standard completion message. 336If 337.Nm 338receives a 339.Dv SIGINT 340signal, the current input and output block counts will 341be written to the standard error output 342in the same format as the standard completion message and 343.Nm 344will exit. 345.Sh DIAGNOSTICS 346The 347.Nm 348utility exits 0 on success or >0 if an error occurs. 349.Sh SEE ALSO 350.Xr cp 1 , 351.Xr mt 1 , 352.Xr tr 1 353.Sh STANDARDS 354The 355.Nm 356utility is expected to be a superset of the 357.St -p1003.2 358standard. 359The 360.Cm files 361operand and the 362.Cm ascii , 363.Cm ebcdic , 364.Cm ibm , 365.Cm oldascii , 366.Cm oldebcdic 367and 368.Cm oldibm 369values are extensions to the 370.Tn POSIX 371standard. 372