DD(C)                                UNIX System V



     Name
          dd - converts and copies a file


     Syntax
          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             Value

          if=file            Input filename; standard input is default

          of=file            Output  filename;  standard   output   is
                             default

          ibs=n              Input block size is n bytes  (default  is
                             BSIZE block size)

          obs=n              Output block size (default is BSIZE block
                             size)

          bs=n               Sets both input and  output  block  size,
                             superseding   ibs   and   obs.    If   no
                             conversion   is    specified,    it    is
                             particularly  efficient  since no in-core
                             copy needs to be done

          cbs=n              Conversion buffer size

          skip=n             Skips n  input  records  before  starting
                             copy

          seek=n             Seeks n records from beginning of  output
                             file before copying

          count=n            Copies only n input records

          conv=ascii         Converts EBCDIC to ASCII

          conv=ebcdic        Converts ASCII to EBCDIC

          conv=ibm           Slightly different map of ASCII to EBCDIC

          conv=lcase         Maps alphabetic characters to lowercase

































































































































































































































































































































































































































































































































































          Option             Value

          conv=ucase         Maps alphabetic characters to uppercase

          conv=swab          Swaps every pair of bytes

          conv=noerror       Does not stop processing on an error

          conv=sync          Pads every input record to ibs

          conv="... , ..."   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 a product.

          cbs is used only if ascii or ebcdic 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 case ASCII characters are  read  into
          the conversion buffer, converted to EBCDIC, 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.


     Examples
          This command reads  an  EBCDIC  tape,  blocked  ten  80-byte
          EBCDIC card images per record, into the ASCII file outfile:

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

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


     See Also
          copy(C), cp(C), tar(C)


     Diagnostics
          f+p records in(out)     Numbers of full and partial  records
                                  read(written)


     Notes
          The ASCII/EBCDIC conversion tables are taken from  the  256-
          character   standard   in  the  CACM  Nov,  1968.   The  ibm
          conversion 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.

          When using dd with a raw device, specify the block size as a
          multiple of 1K.  For example, to use a 9K block size, enter:

               dd if=file of=/dev/rfd0 bs=18b

          You could also enter:

               dd if=file of=/dev/rfd0 bs=9K


     Standards Conformance
          dd is conformant with:
          AT&T SVID Issue 2, Select Code 307-127;
          and The X/Open Portability Guide II of January 1987.


     (printed 2/15/90)                                      DD(C)