linux - dd (1)

       dd - convert a file while copying it

       dd  [--help]  [--version]  [if=file] [of=file] [ibs=bytes]
       [obs=bytes]    [bs=bytes]    [cbs=bytes]     [skip=blocks]
       [seek=blocks]                               [count=blocks]
       [conv={ascii,ebcdic,ibm,block,unblock,lcase,ucase,swab,noer-
       ror,notrunc, sync}]

       This  manual  page  documents  the  GNU version of dd.  dd
       copies a file (from the standard  input  to  the  standard
       output,  by  default)  with  a  user-selectable blocksize,
       while optionally performing conversions on it.

   OPTIONS
       Numbers can be followed by a multiplier:
       b=512, c=1, k=1024, w=2, xm=number m

       --help Print a usage message on standard output  and  exit
              successfully.

       --version
              Print  version  information on standard output then
              exit successfully.

       if=file
              Read from file instead of the standard input.

       of=file
              Write to  file  instead  of  the  standard  output.
              Unless  conv=notrunc is given, truncate file to the
              size specified by seek= (0 bytes if  seek=  is  not
              given).

       ibs=bytes
              Read bytes bytes at a time.

       obs=bytes
              Write bytes bytes at a time.

       bs=bytes
              Read  and write bytes bytes at atime.  Override ibs
              and obs.

       cbs=bytes
              Convert bytes bytes at a time.

       skip=blocks
              Skip blocks ibs-sized blocks at start of input.

       count=blocks
              Copy only blocks ibs-sized input blocks.

       conv=conversion[,conversion...]
              Convert the file as  specified  by  the  conversion
              arguments.
              Conversions:

              ascii  Convert EBCDIC to ASCII.

              ebcdic Convert ASCII to EBCDIC.

              ibm    Convert ASCII to alternate EBCDIC.

              block  Pad  newline-terminated  records  to size of
                     cbs, replacing newline with trailing spaces.

              unblock
                     Replace  trailing  spaces in cbs-sized block
                     with newline.

              lcase  Change uppercase characters to lowercase.

              ucase  Change lowercase characters to uppercase.

              swab   Swap every pair of input bytes.  Unlike  the
                     Unix  dd,  this  works when an odd number of
                     bytes are read.  If the input file  contains
                     an  odd  number  of  bytes, the last byte is
                     simply copied (since  there  is  nothing  to
                     swap it with).

              noerror
                     Continue after read errors.

              notrunc
                     Do not truncate the output file.

              sync   Pad  every  input  block to size of ibs with
                     trailing NULs.