DD(1)                            User Commands
DD(1)



NNAAMMEE
       dd - convert and copy a file

SSYYNNOOPPSSIISS
       dddd [_O_P_E_R_A_N_D]...  dddd
       _O_P_T_I_O_N

DDEESSCCRRIIPPTTIIOONN
       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
              symbol 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
       multiplicative suf‐ fixes: 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;
       conv=notrunc  sug‐
              gested)

       direct use direct I/O for data

              directory fail unless a directory dsync     use
              synchronized I/O for data sync      likewise,
              but also for metadata nonblock  use non-blocking
              I/O  noatime    do  not  update access time
              noctty do not assign controlling terminal from
              file  nofollow   do  not follow symlinks

       Sending a USR1 signal to a running `dd' process makes
       it print I/O sta‐ tistics to standard error and then
       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
              seconds, 271 MB/s

       Options are:

       ----hheellpp display this help and exit

       ----vveerrssiioonn
              output version information and exit

AAUUTTHHOORR
       Written by Paul Rubin, David MacKenzie, and Stuart Kemp.

RREEPPOORRTTIINNGG BBUUGGSS
       Report bugs to <bug-coreutils@gnu.org>.

CCOOPPYYRRIIGGHHTT
       Copyright © 2006 Free Software Foundation, Inc.
       This  is  free  software.   You may redistribute
       copies of it under the terms      of      the
       GNU      General       Public       License
       <http://www.gnu.org/licenses/gpl.html>.   There  is
       NO WARRANTY, to the extent permitted by law.

SSEEEE AALLSSOO
       The full documentation for dddd is maintained as a
       Texinfo  manual.   If the  iinnffoo and dddd
       programs are properly installed at your site, the
       com‐ mand

              iinnffoo dddd

       should give you access to the complete manual.



dd (coreutils) 6.7               December 2006
DD(1)
