dd(1M)                UNIX System V(Essential Utilities)                 dd(1M)


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 sizes may be specified to take advantage of raw
      physical I/O.

      option          values
      if=file         input file name; standard input is default
      of=file         output file name; standard output is default
      ibs=n           input block size n bytes (default 512)
      obs=n           output block size n bytes (default 512)
      bs=n            set both input and output block size, superseding ibs and
                      obs; also, if no conversion is specified, preserve the
                      input block size instead of packing short blocks into the
                      output buffer (this is particularly efficient since no
                      in-core copy need be done)
      cbs=n           conversion buffer size (logical record length)
      files=n         copy and concatenate n input files before terminating
                      (makes sense only where input is a magnetic tape or
                      similar device)
      skip=n          skip n input blocks before starting copy (appropriate for
                      magnetic tape, where iseek is undefined)
      iseek=n         seek n blocks from beginning of input file before copying
                      (appropriate for disk files, where skip can be incredibly
                      slow)
      oseek=n         seek n blocks from beginning of output file before
                      copying
      seek=n          identical to oseek, retained for backward compatibility
      count=n         copy only n input blocks
      conv=ascii      convert EBCDIC to ASCII
           ebcdic     convert ASCII to EBCDIC
           ibm        slightly different map of ASCII to EBCDIC
           block      convert new-line terminated ASCII records to fixed length
           unblock    convert fixed length ASCII records to new-line terminated
                      records
           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 (limit of 5
                      consecutive errors)
           sync       pad every input block 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


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dd(1M)                UNIX System V(Essential Utilities)                 dd(1M)


      multiplication.

      cbs is used only if ascii, unblock, ebcdic, ibm, or block conversion is
      specified.  In the first two cases, cbs characters are copied into the
      conversion buffer, any specified character mapping is done, trailing
      blanks are trimmed and a new-line is added before sending the line to the
      output.  In the latter three cases, characters are read into the
      conversion buffer and blanks are added to make up an output record of
      size cbs.  If cbs is unspecified or zero, the ascii, ebcdic, and ibm
      options convert the character set without changing the block structure of
      the input file; the unblock and block options become a simple file copy.

      After completion, dd reports the number of whole and partial input and
      output blocks.

EXAMPLE
      This command will read an EBCDIC tape blocked ten 80-byte EBCDIC card
      images per tape block into the ASCII file x:

      dd  if=/dev/rmt/0h  of=x  ibs=800  obs=8k  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
      block sizes.

SEE ALSO
      cp(1)

NOTES
      Do not use dd to copy files between filesystems having different block
      sizes.

      Using a  blocked device to copy a file will result in extra nulls being
      added to the file to pad the final block to the block boundary.

DIAGNOSTICS
      f+p records in(out)     numbers of full and partial blocks read(written)

















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