DD(1)                    User Commands                    DD(1)





NAME
       dd - convert and copy a file

SYNOPSIS
       dd [OPERAND]...
       dd OPTION

DESCRIPTION
       Copy  a file, converting and formatting according to the
       operands.

       bs=BYTES
              force ibs=BYTES and obs=BYTES

       cbs=BYTES
              convert BYTES bytes at a time

       conv=CONVS
              convert the file as per the comma separated  sym-
              bol list

       count=BLOCKS
              copy only BLOCKS input blocks

       ibs=BYTES
              read BYTES bytes at a time

       if=FILE
              read from FILE instead of stdin

       iflag=FLAGS
              read as per the comma separated symbol list

       obs=BYTES
              write BYTES bytes at a time

       of=FILE
              write to FILE instead of stdout

       oflag=FLAGS
              write as per the comma separated symbol list

       seek=BLOCKS
              skip BLOCKS obs-sized blocks at start of output

       skip=BLOCKS
              skip BLOCKS ibs-sized blocks at start of input

       status=noxfer
              suppress transfer statistics

       BLOCKS and BYTES may be followed by the following multi-
       plicative suffixes: xM M, c 1, w 2, b 512,  kB  1000,  K
       1024,  MB  1000*1000,  M 1024*1024, GB 1000*1000*1000, G
       1024*1024*1024, and so on for T, P, E, Z, Y.

       Each CONV symbol may be:

       ascii  from EBCDIC to ASCII

       ebcdic from ASCII to EBCDIC

       ibm    from ASCII to alternate EBCDIC

       block  pad newline-terminated  records  with  spaces  to
              cbs-size

       unblock
              replace  trailing spaces in cbs-size records with
              newline

       lcase  change upper case to lower case

       nocreat
              do not create the output file

       excl   fail if the output file already exists

       notrunc
              do not truncate the output file

       ucase  change lower case to upper case

       swab   swap every pair of input bytes

       noerror
              continue after read errors

       sync   pad every input block with NULs to ibs-size; when
              used

              with  block  or  unblock,  pad with spaces rather
              than NULs

              fdatasync  physically  write  output  file   data
              before  finishing  fsync      likewise,  but also
              write metadata

       Each FLAG symbol may be:

       append append mode (makes sense only for output)

       direct use direct I/O for data

       dsync  use synchronized I/O for data

       sync   likewise, but also for metadata

       nonblock
              use non-blocking I/O

       nofollow
              do not follow symlinks

       noctty do not assign controlling terminal from file

       Sending a SIGUSR1 signal to a running `dd' process makes
       it  print  I/O  statistics  to  standard  error, then to
       resume copying.

              $ dd if=/dev/zero of=/dev/null& pid=$!
              $ kill -USR1 $pid; sleep 1; kill $pid

              18335302+0  records  in  18335302+0  records  out
              9387674624  bytes  (9.4  GB) copied, 34.6279 sec-
              onds, 271 MB/s

       Options are:

       --help display this help and exit

       --version
              output version information and exit

AUTHOR
       Written by Paul Rubin, David MacKenzie, and Stuart Kemp.

REPORTING BUGS
       Report bugs to <bug-coreutils@gnu.org>.

COPYRIGHT
       Copyright (C) 2004 Free Software Foundation, Inc.
       This is free software; see the source for copying condi-
       tions.  There is NO warranty; not even for MERCHANTABIL-
       ITY or FITNESS FOR A PARTICULAR PURPOSE.

SEE ALSO
       The full documentation for dd is maintained as a Texinfo
       manual.  If  the  info  and  dd  programs  are  properly
       installed at your site, the command

              info dd

       should give you access to the complete manual.



dd (coreutils) 5.3.0     November 2004                    DD(1)