dd man page on NeXTSTEP

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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=	      input file name; standard input is default
       of=	      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 copy need be done
       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
		      where input is a magtape or similar device).
       seek=n	      seek  n  records	from  beginning	 of output file before
		      copying
       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
	    ... , ... 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, 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 new-line  added  before  sending  the	 line  to  the
       output.	 In  the  latter  three	 cases,	 characters  are read into the
       conversion buffer, 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.

       For example, to read an EBCDIC tape blocked  ten	 80-byte  EBCDIC  card
       images per record into the ASCII file x:

	      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.

SEE ALSO
       cp(1), tr(1)

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
       conventions.  There is no universal solution.
       One must specify ``conv=noerror,sync'' when copying raw disks with  bad
       sectors to insure dd stays synchronized.

       Certain combinations of arguments to conv= are permitted.  However, the
       block or unblock option cannot be combined with ascii, ebcdic  or  ibm.
       Invalid	combinations  silently	ignore	all  but  the  last  mutually-
       exclusive keyword.

4th Berkeley Distribution	April 29, 1985				 DD(1)
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