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DD(1)                       General Commands Manual                      DD(1)



NAME
       dd - convert and copy files with various data formats

SYNOPSIS
       dd [ option=value ] ...

DESCRIPTION
       dd  copies  a  specified input file to a 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.

OPTIONS
       if=name        Input  file  is  taken  from  name;  standard  input  is
                      default.

       of=name        Output  file  is  taken  from  name;  standard output is
                      default.  Note: dd  creates  an  explicit  output  file;
                      therefore  the  seek  option  is  usually  useless  with
                      explicit output except in special cases  such  as  using
                      magnetic tape or raw disk files.

       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, it is par-
                      ticularly  efficient  since no copy need be done.  Block
                      sizes for the Sun386i are 9k for 3.5-inch floppy  disks,
                      and 126b (blocks) for quarter-inch tapes.

       cbs=n          Conversion buffer size.

       skip=n         Skip n input records before starting copy

       files=n        Copy  n input files before terminating (makes sense only
                      when input is a magtape or similar device).

       seek=n         Seek n records from  beginning  of  output  file  before
                      copying.  This option generally only works with magnetic
                      tapes and raw disk files and is otherwise  usually  use-
                      less  if  the explicit output file was named with the of
                      option.

       count=n        Copy only n input records.

       conv=ascii     Convert EBCDIC to ASCII.
            ebcdic    Convert ASCII to EBCDIC.
            ibm       Slightly different map of ASCII to EBCDIC.
            block     Convert variable length records to fixed length.
            unblock   Convert fixed length records to variable length.
            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 record to ibs.
            arg, arg[,...]
                      Several comma-separated conversions, for  a  combination
                      of effects.  For instance, conv=sync,block is useful for
                      reading variable-length output from a pipe.

       Where sizes are specified, a number of bytes is expected.  A number may
       end  with k (kilobytes) to specify multiplication by 1024, b (blocks of
       512 bytes) to specify multiplication by 512, or w  (words)  to  specify
       multiplication  by  4; a pair of numbers may be separated by x to indi-
       cate a product.

       cbs is used only if ascii, unblock, ebcdic, ibm, or block conversion is
       specified.   In the first two cases, cbs characters are placed into the
       conversion buffer, any specified character mapping  is  done,  trailing
       blanks trimmed and NEWLINE added before sending the line to the output.
       In the latter three cases, characters are read into the conversion buf-
       fer, 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
       To read an EBCDIC tape blocked  ten  80-byte  EBCDIC  card  images  per
       record into the ASCII file x:

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

       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
       record sizes.

Sun386i EXAMPLES
       The  following  write  the  file filename to a 3.5-inch floppy and read
       from the floppy into a file filename, respectively:
              example%  dd  if=filename of=/dev/rfd0c bs=9k
              example%  dd  if=/dev/rfd0c of=filename bs=9k

       Sun386i files names are shown in fdformat(1).

SEE ALSO
       cp(1), fdformat(1), tr(1V)

DIAGNOSTICS
       f+p records in(out):
              Numbers of full and partial records 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  conven-
       tions.  There is no universal solution.

       The block and unblock options cannot be combined with the ascii, ebcdic
       or ibm.  Invalid combinations silently ignore all but  the  last  mutu-
       ally-exclusive keyword.



                                28 January 1988                          DD(1)