.\" Copyright (c) 1990, 1993 .\" The Regents of the University of California. All rights reserved. .\" .\" This code is derived from software contributed to Berkeley by .\" Keith Muller of the University of California, San Diego. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. All advertising materials mentioning features or use of this software .\" must display the following acknowledgement: .\" This product includes software developed by the University of .\" California, Berkeley and its contributors. .\" 4. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)dd.1 8.2 (Berkeley) 1/13/94 .\" $FreeBSD: src/bin/dd/dd.1,v 1.19 2002/03/31 20:49:37 keramida Exp $ .\" .Dd January 13, 1994 .Dt DD 1 .Os .Sh NAME .Nm dd .Nd convert and copy a file .Sh SYNOPSIS .Nm .Op Ar operands ... .Sh DESCRIPTION The .Nm utility copies the standard input to the standard output. Input data is read and written in 512-byte blocks. If input reads are short, input from multiple reads are aggregated to form the output block. When finished, .Nm displays the number of complete and partial input and output blocks and truncated input records to the standard error output. .Pp The following operands are available: .\" XXX .Bl -tag -width of=file .It Cm bs Ns = Ns Ar n Set both input and output block size to .Ar n bytes, superseding the .Cm ibs and .Cm obs operands. If no conversion values other than .Cm noerror , .Cm notrunc or .Cm sync are specified, then each input block is copied to the output as a single block without any aggregation of short blocks. .It Cm cbs Ns = Ns Ar n Set the conversion record size to .Ar n bytes. The conversion record size is required by the record oriented conversion values. .It Cm count Ns = Ns Ar n Copy only .Ar n input blocks. .It Cm files Ns = Ns Ar n Copy .Ar n input files before terminating. This operand is only applicable when the input device is a tape. .It Cm ibs Ns = Ns Ar n Set the input block size to .Ar n bytes instead of the default 512. .It Cm if Ns = Ns Ar file Read input from .Ar file instead of the standard input. .It Cm iseek Ns = Ns Ar n Seek on the input file .Ar n blocks. This is synonymous with .Cm skip Ns = Ns Ar n . .It Cm obs Ns = Ns Ar n Set the output block size to .Ar n bytes instead of the default 512. .It Cm of Ns = Ns Ar file Write output to .Ar file instead of the standard output. Any regular output file is truncated unless the .Cm notrunc conversion value is specified. If an initial portion of the output file is seeked past (see the .Cm oseek operand), the output file is truncated at that point. .It Cm oseek Ns = Ns Ar n Seek on the output file .Ar n blocks. This is synonymous with .Cm seek Ns = Ns Ar n . .It Cm seek Ns = Ns Ar n Seek .Ar n blocks from the beginning of the output before copying. On non-tape devices, an .Xr lseek 2 operation is used. Otherwise, existing blocks are read and the data discarded. If the user does not have read permission for the tape, it is positioned using the tape .Xr ioctl 2 function calls. If the seek operation is past the end of file, space from the current end of file to the specified offset is filled with blocks of .Dv NUL bytes. .It Cm skip Ns = Ns Ar n Skip .Ar n blocks from the beginning of the input before copying. On input which supports seeks, an .Xr lseek 2 operation is used. Otherwise, input data is read and discarded. For pipes, the correct number of bytes is read. For all other devices, the correct number of blocks is read without distinguishing between a partial or complete block being read. .It Cm conv Ns = Ns Ar value Ns Op , Ns Ar value ... Where .Cm value is one of the symbols from the following list. .Bl -tag -width ".Cm unblock" .It Cm ascii , oldascii The same as the .Cm unblock value except that characters are translated from .Tn EBCDIC to .Tn ASCII before the records are converted. (These values imply .Cm unblock if the operand .Cm cbs is also specified.) There are two conversion maps for .Tn ASCII . The value .Cm ascii specifies the recommended one which is compatible with .At V . The value .Cm oldascii specifies the one used in historic .At and .No pre- Ns Bx 4.3 reno systems. .It Cm block Treats the input as a sequence of newline or end-of-file terminated variable length records independent of input and output block boundaries. Any trailing newline character is discarded. Each input record is converted to a fixed length output record where the length is specified by the .Cm cbs operand. Input records shorter than the conversion record size are padded with spaces. Input records longer than the conversion record size are truncated. The number of truncated input records, if any, are reported to the standard error output at the completion of the copy. .It Cm ebcdic , ibm , oldebcdic , oldibm The same as the .Cm block value except that characters are translated from .Tn ASCII to .Tn EBCDIC after the records are converted. (These values imply .Cm block if the operand .Cm cbs is also specified.) There are four conversion maps for .Tn EBCDIC . The value .Cm ebcdic specifies the recommended one which is compatible with .At V . The value .Cm ibm is a slightly different mapping, which is compatible with the .At V .Cm ibm value. The values .Cm oldebcdic and .Cm oldibm are maps used in historic .At and .No pre- Ns Bx 4.3 reno systems. .It Cm lcase Transform uppercase characters into lowercase characters. .It Cm noerror Do not stop processing on an input error. When an input error occurs, a diagnostic message followed by the current input and output block counts will be written to the standard error output in the same format as the standard completion message. If the .Cm sync conversion is also specified, any missing input data will be replaced with .Dv NUL bytes (or with spaces if a block oriented conversion value was specified) and processed as a normal input buffer. If the .Cm sync conversion is not specified, the input block is omitted from the output. On input files which are not tapes or pipes, the file offset will be positioned past the block in which the error occurred using .Xr lseek 2 . .It Cm notrunc Do not truncate the output file. This will preserve any blocks in the output file not explicitly written by .Nm . The .Cm notrunc value is not supported for tapes. .It Cm osync Pad the final output block to the full output block size. If the input file is not a multiple of the output block size after conversion, this conversion forces the final output block to be the same size as preceding blocks for use on devices that require regularly sized blocks to be written. This option is incompatible with use of the .Cm bs Ns = Ns Ar n block size specification. .It Cm sparse If one or more output blocks would consist solely of .Dv NUL bytes, try to seek the output file by the required space instead of filling them with .Dv NUL Ns s , resulting in a sparse file. .It Cm swab Swap every pair of input bytes. If an input buffer has an odd number of bytes, the last byte will be ignored during swapping. .It Cm sync Pad every input block to the input buffer size. Spaces are used for pad bytes if a block oriented conversion value is specified, otherwise .Dv NUL bytes are used. .It Cm ucase Transform lowercase characters into uppercase characters. .It Cm unblock Treats the input as a sequence of fixed length records independent of input and output block boundaries. The length of the input records is specified by the .Cm cbs operand. Any trailing space characters are discarded and a newline character is appended. .El .El .Pp Where sizes are specified, a decimal, octal, or hexadecimal number of bytes is expected. If the number ends with a .Dq Li b , .Dq Li k , .Dq Li m , .Dq Li g , or .Dq Li w , the number is multiplied by 512, 1024 (1K), 1048576 (1M), 1073741824 (1G) or the number of bytes in an integer, respectively. Two or more numbers may be separated by an .Dq Li x to indicate a product. .Pp When finished, .Nm displays the number of complete and partial input and output blocks, truncated input records and odd-length byte-swapping blocks to the standard error output. A partial input block is one where less than the input block size was read. A partial output block is one where less than the output block size was written. Partial output blocks to tape devices are considered fatal errors. Otherwise, the rest of the block will be written. Partial output blocks to character devices will produce a warning message. A truncated input block is one where a variable length record oriented conversion value was specified and the input line was too long to fit in the conversion record or was not newline terminated. .Pp Normally, data resulting from input or conversion or both are aggregated into output blocks of the specified size. After the end of input is reached, any remaining output is written as a block. This means that the final output block may be shorter than the output block size. .Pp If .Nm receives a .Dv SIGINFO (see the .Cm status argument for .Xr stty 1 ) signal, the current input and output block counts will be written to the standard error output in the same format as the standard completion message. If .Nm receives a .Dv SIGINT signal, the current input and output block counts will be written to the standard error output in the same format as the standard completion message and .Nm will exit. .Sh DIAGNOSTICS .Ex -std .Sh SEE ALSO .Xr cp 1 , .Xr tr 1 .Sh STANDARDS The .Nm utility is expected to be a superset of the .St -p1003.2 standard. The .Cm files operand and the .Cm ascii , .Cm ebcdic , .Cm ibm , .Cm oldascii , .Cm oldebcdic and .Cm oldibm values are extensions to the \*[Px] standard.