1.\" $NetBSD: dd.1,v 1.32 2016/08/18 22:43:49 sevan Exp $ 2.\" 3.\" Copyright (c) 1990, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" This code is derived from software contributed to Berkeley by 7.\" Keith Muller of the University of California, San Diego. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 3. Neither the name of the University nor the names of its contributors 18.\" may be used to endorse or promote products derived from this software 19.\" without specific prior written permission. 20.\" 21.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31.\" SUCH DAMAGE. 32.\" 33.\" @(#)dd.1 8.2 (Berkeley) 1/13/94 34.\" 35.Dd August 18, 2016 36.Dt DD 1 37.Os 38.Sh NAME 39.Nm dd 40.Nd convert and copy a file 41.Sh SYNOPSIS 42.Nm 43.Op operand ... 44.Sh DESCRIPTION 45The 46.Nm 47utility copies the standard input to the standard output. 48Input data is read and written in 512-byte blocks. 49If input reads are short, input from multiple reads are aggregated 50to form the output block. 51When finished, 52.Nm 53displays the number of complete and partial input and output blocks 54and truncated input records to the standard error output. 55.Pp 56The following operands are available: 57.Bl -tag -width of=file 58.It Cm bs= Ns Ar n 59Set both input and output block size, superseding the 60.Cm ibs 61and 62.Cm obs 63operands. 64If no conversion values other than 65.Cm noerror , 66.Cm notrunc 67or 68.Cm sync 69are specified, then each input block is copied to the output as a 70single block without any aggregation of short blocks. 71.It Cm cbs= Ns Ar n 72Set the conversion record size to 73.Va n 74bytes. 75The conversion record size is required by the record oriented conversion 76values. 77.It Cm count= Ns Ar n 78Copy only 79.Va n 80input blocks. 81.It Cm files= Ns Ar n 82Copy 83.Va n 84input files before terminating. 85This operand is only applicable when the input device is a tape. 86.It Cm ibs= Ns Ar n 87Set the input block size to 88.Va n 89bytes instead of the default 512. 90.It Cm if= Ns Ar file 91Read input from 92.Ar file 93instead of the standard input. 94.It Cm iflag= Ns Ar flags 95Use comma-separated 96.Ar flags 97when calling 98.Xr open 2 99for the input file. 100The possible values are 101.Va O_ 102flags documented in 103.Xr open 2 , 104specified as lowercase and with the leading 105.Va O_ 106removed. 107Default value is 108.Va rdonly . 109.It Cm iseek= Ns Ar n 110Seek on the input file 111.Ar n 112blocks. 113This is synonymous with 114.Cm skip= Ns Ar n . 115.It Cm msgfmt= Ns Ar fmt 116Specify the message format 117.Ar fmt 118to be used when writing information to standard output. 119Possible values are: 120.Bl -tag -width xxxxx -offset indent -compact 121.It quiet 122turns off information summary report except for errors and 123.Cm progress . 124.It posix 125default information summary report as specified by POSIX. 126.It human 127default information summary report extended with human-readable 128values. 129.El 130.Pp 131When 132.Ar fmt 133does not correspond to any value given above, 134it contains a string that will be used as format specifier 135for the information summary output. 136Each conversion specification is introduced by the character 137.Cm % . 138The following ones are available: 139.Bl -tag -width xx -offset indent -compact 140.It b 141total number of bytes transferred 142.It B 143total number of bytes transferred in 144.Xr humanize_number 3 145format 146.It e 147speed transfer 148.It E 149speed transfer in 150.Xr humanize_number 3 151format 152.It i 153number of partial input block(s) 154.It I 155number of full input block(s) 156.It o 157number of partial output block(s) 158.It O 159number of full output block(s) 160.It s 161time elapsed since the beginning in 162.Do seconds.ms Dc 163format 164.It p 165number of sparse output blocks 166.It t 167number of truncated blocks 168.It w 169number of odd-length swab blocks 170.It P 171singular/plural of 172.Do block Dc 173depending on number of sparse blocks 174.It T 175singular/plural of 176.Do block Dc 177depending on number of truncated blocks 178.It W 179singular/plural of 180.Do block Dc 181depending on number of swab blocks 182.El 183.It Cm obs= Ns Ar n 184Set the output block size to 185.Va n 186bytes instead of the default 512. 187.It Cm of= Ns Ar file 188Write output to 189.Ar file 190instead of the standard output. 191Any regular output file is truncated unless the 192.Cm notrunc 193conversion value is specified. 194If an initial portion of the output file is skipped (see the 195.Cm seek 196operand) 197the output file is truncated at that point. 198.It Cm oflag= Ns Ar flags 199Same as 200.Cm iflag 201but for the call to 202.Xr open 2 203on the output file. 204The default value is 205.Va creat , 206which should be explicitly added in 207.Cm oflag 208in order to output to a nonexistent file. 209The default or specified value is or'ed with 210.Va rdwr 211for a first 212.Xr open 2 213attempt, then on failure with 214.Va wronly 215on a second attempt. 216In both cases, 217.Va trunc 218is automatically added if none of 219.Cm oseek , 220.Cm seek , 221or 222.Cm conv=notrunc 223operands are used, 224.It Cm oseek= Ns Ar n 225Seek on the output file 226.Ar n 227blocks. 228This is synonymous with 229.Cm seek= Ns Ar n . 230.It Cm seek= Ns Ar n 231Seek 232.Va n 233blocks from the beginning of the output before copying. 234On non-tape devices, an 235.Xr lseek 2 236operation is used. 237Otherwise, existing blocks are read and the data discarded. 238If the user does not have read permission for the tape, it is positioned 239using the tape 240.Xr ioctl 2 241function calls. 242If the seek operation is past the end of file, space from the current 243end of file to the specified offset is filled with blocks of 244.Tn NUL 245bytes. 246.It Cm skip= Ns Ar n 247Skip 248.Va n 249blocks from the beginning of the input before copying. 250On input which supports seeks, an 251.Xr lseek 2 252operation is used. 253Otherwise, input data is read and discarded. 254For pipes, the correct number of bytes is read. 255For all other devices, the correct number of blocks is read without 256distinguishing between a partial or complete block being read. 257.It Cm progress= Ns Ar n 258Switch on display of progress if 259.Va n 260is set to any non-zero value. 261This will cause a 262.Dq \&. 263to be printed (to the standard error output) for every 264.Va n 265full or partial blocks written to the output file. 266.Sm off 267.It Cm conv= Cm value Op \&, Cm value \&... 268.Sm on 269Where 270.Cm value 271is one of the symbols from the following list. 272.Bl -tag -width unblock 273.It Cm ascii , oldascii 274The same as the 275.Cm unblock 276value except that characters are translated from 277.Tn EBCDIC 278to 279.Tn ASCII 280before the 281records are converted. 282(These values imply 283.Cm unblock 284if the operand 285.Cm cbs 286is also specified.) 287There are two conversion maps for 288.Tn ASCII . 289The value 290.Cm ascii 291specifies the recommended one which is compatible with 292.At V . 293The value 294.Cm oldascii 295specifies the one used in historic 296.Tn AT\*[Am]T 297and pre- 298.Bx 4.3 Reno 299systems. 300.It Cm block 301Treats the input as a sequence of newline or end-of-file terminated variable 302length records independent of input and output block boundaries. 303Any trailing newline character is discarded. 304Each input record is converted to a fixed length output record where the 305length is specified by the 306.Cm cbs 307operand. 308Input records shorter than the conversion record size are padded with spaces. 309Input records longer than the conversion record size are truncated. 310The number of truncated input records, if any, are reported to the standard 311error output at the completion of the copy. 312.It Cm ebcdic , ibm , oldebcdic , oldibm 313The same as the 314.Cm block 315value except that characters are translated from 316.Tn ASCII 317to 318.Tn EBCDIC 319after the 320records are converted. 321(These values imply 322.Cm block 323if the operand 324.Cm cbs 325is also specified.) 326There are four conversion maps for 327.Tn EBCDIC . 328The value 329.Cm ebcdic 330specifies the recommended one which is compatible with 331.At V . 332The value 333.Cm ibm 334is a slightly different mapping, which is compatible with the 335.At V 336.Cm ibm 337value. 338The values 339.Cm oldebcdic 340and 341.Cm oldibm 342are maps used in historic 343.Tn AT\*[Am]T 344and pre 345.Bx 4.3 Reno 346systems. 347.It Cm lcase 348Transform uppercase characters into lowercase characters. 349.It Cm noerror 350Do not stop processing on an input error. 351When an input error occurs, a diagnostic message followed by the current 352input and output block counts will be written to the standard error output 353in the same format as the standard completion message. 354If the 355.Cm sync 356conversion is also specified, any missing input data will be replaced 357with 358.Tn NUL 359bytes (or with spaces if a block oriented conversion value was 360specified) and processed as a normal input buffer. 361If the 362.Cm sync 363conversion is not specified, the input block is omitted from the output. 364On input files which are not tapes or pipes, the file offset 365will be positioned past the block in which the error occurred using 366.Xr lseek 2 . 367.It Cm notrunc 368Do not truncate the output file. 369This will preserve any blocks in the output file not explicitly written 370by 371.Nm . 372The 373.Cm notrunc 374value is not supported for tapes. 375.It Cm osync 376Pad the final output block to the full output block size. 377If the input file is not a multiple of the output block size 378after conversion, this conversion forces the final output block 379to be the same size as preceding blocks for use on devices that require 380regularly sized blocks to be written. 381This option is incompatible with use of the 382.Cm bs= Ns Ar n 383block size specification. 384.It Cm sparse 385If one or more non-final output blocks would consist solely of 386.Dv NUL 387bytes, try to seek the output file by the required space instead of 388filling them with 389.Dv NUL Ns s . 390This results in a sparse file on some file systems. 391.It Cm swab 392Swap every pair of input bytes. 393If an input buffer has an odd number of bytes, the last byte will be 394ignored during swapping. 395.It Cm sync 396Pad every input block to the input buffer size. 397Spaces are used for pad bytes if a block oriented conversion value is 398specified, otherwise 399.Tn NUL 400bytes are used. 401.It Cm ucase 402Transform lowercase characters into uppercase characters. 403.It Cm unblock 404Treats the input as a sequence of fixed length records independent of input 405and output block boundaries. 406The length of the input records is specified by the 407.Cm cbs 408operand. 409Any trailing space characters are discarded and a newline character is 410appended. 411.El 412.El 413.Pp 414Where sizes are specified, a decimal number of bytes is expected. 415Two or more numbers may be separated by an 416.Dq x 417to indicate a product. 418Each number may have one of the following optional suffixes: 419.Bl -tag -width 3n -offset indent -compact 420.It b 421Block; multiply by 512 422.It k 423Kibi; multiply by 1024 (1 KiB) 424.It m 425Mebi; multiply by 1048576 (1 MiB) 426.It g 427Gibi; multiply by 1073741824 (1 GiB) 428.It t 429Tebi; multiply by 1099511627776 (1 TiB) 430.It w 431Word; multiply by the number of bytes in an integer 432.El 433.Pp 434When finished, 435.Nm 436displays the number of complete and partial input and output blocks, 437truncated input records and odd-length byte-swapping blocks to the 438standard error output. 439A partial input block is one where less than the input block size 440was read. 441A partial output block is one where less than the output block size 442was written. 443Partial output blocks to tape devices are considered fatal errors. 444Otherwise, the rest of the block will be written. 445Partial output blocks to character devices will produce a warning message. 446A truncated input block is one where a variable length record oriented 447conversion value was specified and the input line was too long to 448fit in the conversion record or was not newline terminated. 449.Pp 450Normally, data resulting from input or conversion or both are aggregated 451into output blocks of the specified size. 452After the end of input is reached, any remaining output is written as 453a block. 454This means that the final output block may be shorter than the output 455block size. 456.Pp 457If 458.Nm 459receives a 460.Dv SIGINFO 461signal 462(see the 463.Ic status 464argument for 465.Xr stty 1 ) , 466the current input and output block counts will 467be written to the standard error output 468in the same format as the standard completion message. 469If 470.Nm 471receives a 472.Dv SIGINT 473signal, the current input and output block counts will 474be written to the standard error output 475in the same format as the standard completion message and 476.Nm 477will exit. 478.Sh EXIT STATUS 479The 480.Nm 481utility exits 0 on success and \*[Gt]0 if an error occurred. 482.Sh EXAMPLES 483To print summary information in human-readable form: 484.Pp 485.Dl dd if=/dev/zero of=/dev/null count=1 msgfmt=human 486.Pp 487To customize the information summary output and print it through 488.Xr unvis 3 : 489.Bd -literal -offset indent 490dd if=/dev/zero of=/dev/null count=1 \e 491 msgfmt='speed:%E, in %s seconds\en' 2\*[Gt]\*[Am]1 | unvis 492.Ed 493.Sh SEE ALSO 494.Xr cp 1 , 495.Xr mt 1 , 496.Xr tr 1 497.Sh STANDARDS 498The 499.Nm 500utility is expected to be a superset of the 501.St -p1003.2 502standard. 503The 504.Cm files 505and 506.Cm msgfmt 507operands and the 508.Cm ascii , 509.Cm ebcdic , 510.Cm ibm , 511.Cm oldascii , 512.Cm oldebcdic 513and 514.Cm oldibm 515values are extensions to the 516.Tn POSIX 517standard. 518.Sh HISTORY 519A 520.Nm 521utility appeared in 522.At v5 . 523