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=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 (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 in-core copy need be done
          cbs=n           conversion buffer size
          skip=n          skip n input blocks before starting copy
          seek=n          seek n blocks from beginning of output file
                          before copying; dd creates the specified
                          output file (see creat(2)), which insures
                          the length of the file will be zero for
                          regular files; seeking n blocks from the
                          beginning of the output file will fill the
                          skipped area with zeros (nulls).
          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
               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 block to ibs
               type, type several comma-separated conversions, where
                          type is one of the above conversions listed
                          for conv.

          multi=in        input file is multi-volume
                out  output file is multi-volume
                in,out
                     both the input file and output file are multi-
                     volume

          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



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     dd(1)                                                       dd(1)



          separated by x to indicate a product.

          cbs is used only if ascii, ebcdic, or ibm conversion is
          specified.  In the former case, cbs characters are placed
          into the conversion buffer, converted to ASCII, and trailing
          blanks trimmed and newline added before sending the line to
          the output.  In the latter two cases, ASCII characters are
          read into the conversion buffer, converted to EBCDIC (or the
          IBM version of EBCDIC), and blanks added to make up an
          output block of size cbs.

          If multi-volume input(output) is specified, a prompt is
          given on end-of-file to allow another volume to be mounted.

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

     EXAMPLE
               dd  if=/dev/rmt/0m  of=x  ibs=800  cbs=80
               conv=ascii,lcase

          will read an EBCDIC tape blocked ten 80-byte EBCDIC card
          images per block into the ASCII file x.

          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 block sizes.

     FILES
          /bin/dd

     SEE ALSO
          cp(1).

     DIAGNOSTICS
          f+p blocks in(out)
                    numbers of full and partial blocks 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.

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







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