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dd(1) [bsd man page]

DD(1)							      General Commands Manual							     DD(1)

dd - convert and copy a file SYNOPSIS
dd [option=value] ... DESCRIPTION
Dd copies the specified input file to the specified output with possible conversions. The standard input and output are used by default. The input and output block size may be specified to take advantage of raw physical I/O. option values if= input file name; standard input is default of= output file name; standard output is default ibs=n input block size n bytes (default 512) obs=n output block size (default 512) bs=n set both input and output block size, superseding ibs and obs; also, if no conversion is specified, it is particularly effi- cient since no copy need be done cbs=n conversion buffer size skip=n skip n input records before starting copy files=n copy n input files before terminating (makes sense only where input is a magtape or similar device). seek=n seek n records from beginning of output file before copying count=n copy only n input records conv=ascii convert EBCDIC to ASCII ebcdic convert ASCII to EBCDIC ibm slightly different map of ASCII to EBCDIC block convert variable length records to fixed length unblock convert fixed length records to variable length lcase map alphabetics to lower case ucase map alphabetics to upper case swab swap every pair of bytes noerror do not stop processing on an error sync pad every input record to ibs ... , ... several comma-separated conversions Where sizes are specified, a number of bytes is expected. A number may end with k, b or w to specify multiplication by 1024, 512, or 2 respectively; a pair of numbers may be separated by x to indicate a product. Cbs is used only if ascii, unblock, ebcdic, ibm, or block conversion is specified. In the first two cases, cbs characters are placed into the conversion buffer, any specified character mapping is done, trailing blanks trimmed and new-line added before sending the line to the output. In the latter three cases, characters are read into the conversion buffer, and blanks added to make up an output record of size cbs. After completion, dd reports the number of whole and partial input and output blocks. For example, to read an EBCDIC tape blocked ten 80-byte EBCDIC card images per record into the ASCII file x: dd if=/dev/rmt0 of=x ibs=800 cbs=80 conv=ascii,lcase Note the use of raw magtape. Dd is especially suited to I/O on the raw physical devices because it allows reading and writing in arbitrary record sizes. SEE ALSO
cp(1), tr(1) DIAGNOSTICS
f+p records in(out): numbers of full and partial records read(written) BUGS
The ASCII/EBCDIC conversion tables are taken from the 256 character standard in the CACM Nov, 1968. The `ibm' conversion, while less blessed as a standard, corresponds better to certain IBM print train conventions. There is no universal solution. One must specify ``conv=noerror,sync'' when copying raw disks with bad sectors to insure dd stays synchronized. Certain combinations of arguments to conv= are permitted. However, the block or unblock option cannot be combined with ascii, ebcdic or ibm. Invalid combinations silently ignore all but the last mutually-exclusive keyword. 4th Berkeley Distribution April 29, 1985 DD(1)

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DD(1)									FSF								     DD(1)

dd - convert and copy a file SYNOPSIS
Copy a file, converting and formatting according to the options. bs=BYTES force ibs=BYTES and obs=BYTES cbs=BYTES convert BYTES bytes at a time conv=KEYWORDS convert the file as per the comma separated keyword list count=BLOCKS copy only BLOCKS input blocks ibs=BYTES read BYTES bytes at a time if=FILE read from FILE instead of stdin obs=BYTES write BYTES bytes at a time of=FILE write to FILE instead of stdout seek=BLOCKS skip BLOCKS obs-sized blocks at start of output skip=BLOCKS skip BLOCKS ibs-sized blocks at start of input --help display this help and exit --version output version information and exit BLOCKS and BYTES may be followed by the following multiplicative suffixes: xM M, c 1, w 2, b 512, kB 1000, K 1024, MB 1,000,000, M 1,048,576, GB 1,000,000,000, G 1,073,741,824, and so on for T, P, E, Z, Y. Each KEYWORD may be: ascii from EBCDIC to ASCII ebcdic from ASCII to EBCDIC ibm from ASCII to alternated EBCDIC block pad newline-terminated records with spaces to cbs-size unblock replace trailing spaces in cbs-size records with newline lcase change upper case to lower case notrunc do not truncate the output file ucase change lower case to upper case swab swap every pair of input bytes noerror continue after read errors sync pad every input block with NULs to ibs-size; when used with block or unblock, pad with spaces rather than NULs AUTHOR
Written by Paul Rubin, David MacKenzie, and Stuart Kemp. REPORTING BUGS
Report bugs to <>. COPYRIGHT
Copyright (C) 2002 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICU- LAR PURPOSE. SEE ALSO
The full documentation for dd is maintained as a Texinfo manual. If the info and dd programs are properly installed at your site, the com- mand info dd should give you access to the complete manual. dd (coreutils) 4.5.3 February 2003 DD(1)

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