• 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
  
  BLOCKS and BYTES may be followed by the following multiplicative 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 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 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 copying. <(>CW$ dd if=/dev/zero of=/dev/null& pid=$!
  <(>CW$ 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.
• 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/>
• COPYRIGHT
  
  Copyright © 2009 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 redistribute 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 (aqdd invocation(aq
  
  should give you access to the complete manual.

Current Users: 78 © 1999-2009 PenguinSoft. All trademarks and copyrights on this page are owned by their respective companies. Linux is a trademark of Linus Torvalds.