NAME
	  dd - Converts	and copies a file

     SYNOPSIS
	  dd [option=value ...]


     DESCRIPTION
	  The dd command reads the specified input file	or standard
	  input, does the specified conversions, and copies it to the
	  specified output file	or standard output.  The input and
	  output block size may	be specified to	take advantage of raw
	  physical I/O.	 The terms block and record refer to the quan-
	  tity of data read or written by dd in	one operation and are
	  not necessarily the same size	as a disk block.

	  Where	sizes are specified, a number of bytes is expected.  A
	  number may end with w, b, or k to specify multiplication by
	  2, 512, or 1024, respectively; a pair	of numbers can be
	  separated by an x to indicate	a product.

	  The cbs specification	is used	if one of the following
	  conversions is specified:  ascii, unblock, ebcdic, ibm, or
	  block.  For the first	two conversions, dd places characters
	  in a conversion buffer of size cbs, converts these charac-
	  ters to ASCII, trims trailing	spaces,	and adds newline char-
	  acters before	sending	data to	the specified output.  For the
	  latter three cases, dd places	ASCII characters in the
	  conversion buffer, converts these characters to EBCDIC, and
	  adds trailing	spaces to create an output record of size cbs.

	  After	it finishes, dd	reports	the number of whole and	par-
	  tial input and output	blocks.

	Options
	  if=input_file
	      Specifies	the input filename; standard input is the
	      default.

	  of=output_file
	      Specifies	the output filename; standard output is	the
	      default.

	  ibs=number
	      Specifies	the input block	size in	bytes; the default is
	      512.

	  obs=number
	      Specifies	the output block size in bytes;	the default is
	      512.

	  bs=number
	      Specifies	both the input and output block	size,
	      superseding ibs and obs.	If no conversion other than
	      sync and noerror is specified, each input	block is
	      copied to	the output as a	single block without aggregat-
	      ing short	blocks.

	  cbs=number
	      Specifies	the conversion block size for block and
	      unblock in bytes.	 A value of 0 (zero) inhibits block
	      and unblock conversions.

	  skip=number
	      Skips number input records before	starting copy.

	  files=number
	      Copies number input files	before terminating (makes
	      sense only where input is	a magnetic tape	or similar
	      device).

	  seek=number
	      Seeks to the numberth record from	the beginning of out-
	      put file before copying.

	  count=number
	      Copies only number input records.

	  conv=specification[,specification ...]
	      Specifies	one or more of the following conversions:


	      ascii
		  Converts EBCDIC to ASCII.

	      block
		  Converts variable-length records to fixed-length.

	      ebcdic
		  Converts ASCII to EBCDIC.

	      ibm Performs a slightly different	map of ASCII to
		  EBCDIC.

	      unblock
		  Converts fixed-length	records	to variable-length.

	      lcase
		  Makes	all alphabetic characters lowercase letters.

	      ucase
		  Makes	all alphabetic characters uppercase letters.

	      swab

		  Swaps	every pair of bytes.

	      noerror
		  Does not stop	processing on an error.

	      sync
		  Pads every input record to ibs.

	      ... , ...
		  Allows several comma-separated conversions.


     EXAMPLES
	   1.  To read an EBCDIC tape blocked ten 80-byte EBCDIC card
	       images per record into the ASCII	file x,	enter:

	       dd if=/dev/rmt0 of=x ibs=800 cbs=80 conv=ascii,lcase



	       Note the	use of raw magnetic tape.  dd is especially
	       suited to I/O on	the raw	physical devices because it
	       allows reading and writing in arbitrary record sizes.

	   2.  To convert an ASCII text	file to	EBCDIC,	enter:

	       dd if=text.ascii	of=text.ebcdic conv=ebcdic



	       This converts text.ascii	to EBCDIC representation,
	       storing this in text.ebcdic.


     NOTES
	   1.  The ASCII/EBCDIC	conversion tables are taken from the
	       256 character standard in the CACM November, 1968.
	       There is	no universal standard for EBCDIC/ASCII trans-
	       lation.

	   2.  One must	specify	conv=noerror,sync when copying raw
	       disks with bad sectors to ensure	dd stays synchronized.

	   3.  Certain combinations of arguments to conv= are permit-
	       ted.  However, the block	or unblock option cannot be
	       combined	with ascii, ebcdic, or ibm.  Invalid combina-
	       tions silently ignore all but the last mutually
	       exclusive keyword.

	   4.  If you need to use dd to	copy to	a streaming tape and
	       the data	is an odd length (not a	multiple of 512
	       bytes), you must	use the	conv=sync flag to fill the
	       last record.  Streaming tape devices permit only	multi-
	       ples of 512 bytes.


     DIAGNOSTICS
	  This message specifies the number of full and	partial
	  records both read and	written:

	  f+p records in
	  f+p records out



	  The number of	full records read or written (f) refers	to the
	  blocks of data of size ibs or	obs.  The number of partial
	  records read or written (p) refers to	the blocks of data
	  smaller than ibs or obs.

	  The following	message	specifies the number of	truncated
	  blocks:

	  n truncated block(s)


     RELATED INFORMATION
	  Commands:  cp(1), cpio(1), pax(1), tar(1), tr(1), trbsd(1).

	  "Using Internationalization Features"	in the OSF/1 User's
	  Guide.