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
          read  and  write  BYTES  bytes  at  a  time  (also  see
          ibs=,obs=)

     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 (default: 512)

     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 (default: 512)

     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





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User Commands                                               DD(1)



     BLOCKS and BYTES may be followed by the following  multipli-
     cative  suffixes:  c =1, w =2, b =512, kB =1000, K =1024, MB
     =1000*1000,  M  =1024*1024,  xM  =M  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  new-
          line

     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:




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User Commands                                               DD(1)



     append
          append mode (makes sense only for output;  conv=notrunc
          suggested)

     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

     fullblock
          accumulate full blocks of input (iflag only)

     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 statistics to standard error and then resume copy-
     ing.

          $ 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:

     --help
          display this help and exit

     --version
          output version information and exit

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





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User Commands                                               DD(1)



REPORTING BUGS
     Report dd bugs to bug-coreutils@gnu.org
     GNU             coreutils             home             page:
     <http://www.gnu.org/software/coreutils/>
     General        help        using        GNU        software:
     <http://www.gnu.org/gethelp/>
     Report        dd         translation         bugs         to
     <http://translationproject.org/team/>

COPYRIGHT
     Copyright c 2010 Free  Software  Foundation,  Inc.   License
     GPLv3+:      GNU      GPL     version     3     or     later
     <http://gnu.org/licenses/gpl.html>.
     This is free software: you are free to change and  redistri-
     bute  it.   There is NO WARRANTY, to the extent permitted by
     law.

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 coreutils dd invocation

     should give you access to the complete manual.






























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