BSD 2.11 - man page for dd (bsd section 1)

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DD(1)											    DD(1)

NAME
       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 efficient 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 sepa-
       rated 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 char-
       acter 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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