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 dd(1)								       dd(1)




 NAME
      dd - convert, reblock, translate, and copy a (tape) file

 SYNOPSIS
      dd [option=value] ...

 DESCRIPTION
      dd copies the specified input file to the specified output file with
      possible conversions.  The standard input and output are used by
      default.	Input and output block size can be specified to take
      advantage of raw physical I/O.  Upon completion, dd reports the number
      of whole and partial input and output records.

    Options
      dd recognizes the following option=value pairs:

	   if=file	  Input file name; default is standard input.

	   of=file	  Output file name; default is standard output.	 The
			  output file is created using the same owner and
			  group used by creat().

	   ibs=n	  Input block size is n bytes; default is 512.

	   obs=n	  Output block size is n bytes; default is 512.

	   bs=n		  Set both input and output block size to the same
			  size, superseding ibs and obs.  This option is
			  particularly efficient if no conversion (conv
			  option) is specified, because no in-core copy is
			  necessary.

	   cbs=n	  Conversion buffer size is n bytes.

	   skip=n	  Skip n input blocks before starting copy.

	   iseek=n	  Skip n input blocks before starting copy.  (This
			  is an alias for the skip option.)

	   seek=n	  Skip n blocks from beginning of output file before
			  copying.

	   oseek=n	  Skip n blocks from beginning of output file before
			  copying.  (This is an alias for the seek option.)

	   count=n	  Copy only n input blocks.

	   files=n	  Copy and concatenate n input files.  This option
			  should be used only when the input file is a
			  magnetic tape device.




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 dd(1)								       dd(1)




	   conv=value [,value ...]
			  Where values are comma-separated symbols from the
			  following list.

			  ascii		    Convert EBCDIC to ASCII.

			  ebcdic	    Convert ASCII to EBCDIC.

			  ibm		    Convert ASCII to EBCDIC using an
					    alternate conversion table.

					    The ascii, ebcdic, and ibm
					    values are mutually exclusive.

			  block		    Convert each newline-terminated
					    or end-of-file-terminated input
					    record to a record with a fixed
					    length specified by cbs.  Any
					    newline character is removed,
					    and space characters are used to
					    fill the block to size cbs.
					    Lines that are longer than cbs
					    are truncated; the number of
					    truncated lines (records) is
					    reported (see DIAGNOSTICS
					    below).

					    The block and unblock values are
					    mutually exclusive.

			  unblock	    Convert fixed-length input
					    records to variable-length
					    records.  For each input record,
					    cbs bytes are read, trailing
					    space characters are deleted,
					    and a newline character is
					    appended.

			  lcase		    Map upper-case input characters
					    to the corresponding lower-case
					    characters.

					    The lcase and ucase values are
					    mutually exclusive.

			  ucase		    Map lower-case input characters
					    to the corresponding upper-case
					    characters.

			  swab		    Swap every pair of input bytes.




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 dd(1)								       dd(1)




			  noerror	    Do not stop processing on an
					    input error.  If the sync
					    conversion symbol is also
					    specified, missing input is
					    replaced with null bytes and
					    processed normally; otherwise,
					    the input block is omitted from
					    the output.

			  notrunc	    Do not truncate existing output
					    file.  Blocks in the output file
					    not overwritten by this
					    invocation of dd are preserved.

			  sync		    Pad every input block to size
					    ibs.  If block or unblock is
					    also specified, pad with space
					    characters; otherwise, pad with
					    null bytes.

      Where sizes are required, n indicates a numerical value in bytes.
      Numbers can be specified using the forms:

	   n	     for n bytes
	   nk	     for n Kbytes (n x 1024),
	   nb	     for n blocks (n x 512), or
	   nw	     for n words (n x 2).

      To indicate a product, use x to separate number pairs.

      The cbs option is used when block, unblock, ascii or ebcdic conversion
      is specified.  In case of ascii, cbs characters are placed into the
      conversion buffer, converted to ASCII, trailing blanks are trimmed,
      and a newline is added before sending the line to the output.  In case
      of ebcdic, ASCII characters are read into the conversion buffer,
      converted to EBCDIC, and blanks are added to make up an output block
      of size cbs.

 EXTERNAL INFLUENCES
    International Code Set Support
      Single- and multi-byte character code sets are supported.

    Environment Variables
      The following environment variables affect execution of dd:

      LANG determines the locale when LC_ALL and a corresponding variable
      (beginning with LC_) do not specify a locale.

      LC_ALL determines the locale used to override any values set by LANG
      or any environment variables beginning with LC_.




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 dd(1)								       dd(1)




      The LC_CTYPE variable determines the locale for the interpretation of
      sequences of bytes of text data as characters (single-byte/multi-byte
      characters, upper-case/lower-case characters).

      The LC_MESSAGES variable determines the language in which messages are
      written.

 RETURN VALUE
      Exit values are:

	    0	   Successful completion.
	   >&gt&gt>0	   Error condition occurred.

 DIAGNOSTICS
      Upon completion, dd reports the number of input and output records:

	   f+p records in	    Number of full and partial blocks read.
	   f+p records out	    Number of full and partial blocks
				    written.

      When conv=block is specified and there is at least one truncated
      block, the number of truncated records is also reported:

	   n truncated records

 EXAMPLES
      Read an EBCDIC tape blocked ten 80-byte EBCDIC card images per block
      into an ASCII file named x:

	   dd if=/dev/rmt/c0t0d0BEST of=x ibs=800 cbs=80 conv=ascii,lcase

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

 WARNINGS
      Some devices, such as 1/2-inch magnetic tapes, are incapable of
      seeking.	Such devices may be positioned prior to running dd by using
      mt(1) or some other appropriate command.	The skip, seek, iseek and
      oseek options do work for such devices.  However, skipping blocks
      using these options is slow on devices that cannot seek, since the
      blocks must actually be read to get to the desired position on the
      tape.

      ASCII and EBCDIC conversion tables are taken from the 256-character
      ACM standard, Nov, 1968.	The ibm conversion, while less widely
      accepted as a standard, corresponds better to certain IBM print train
      conventions.  There is no universal solution.

      Newline characters are inserted only on conversion to ASCII; padding
      is done only on conversion to EBCDIC.  These should be separate



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 dd(1)								       dd(1)




      options.

      If if or of refers to a raw disk, bs should always be a multiple of
      the sector size of the disk.  By default, bs is 512 bytes.  If the
      sector size of the disk is different from 512 bytes, bs should be
      specified using a multiple of sector size.  The character special
      (raw) device file should always be used for devices.

      It is entirely up to the user to insure there is enough room in the
      destination file, file system and/or device to contain the output
      since dd cannot pre-determine the required space after conversion.

 SEE ALSO
      cp(1), mt(1), tr(1), disk(7), mt(7).

 STANDARDS CONFORMANCE
      dd: SVID2, SVID3, XPG2, XPG3, XPG4, POSIX.2





































 Hewlett-Packard Company	    - 5 -   HP-UX Release 11i: November 2000