Manpage of DD

DD

Section: User Commands (1)
Updated: August 2006
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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 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 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 USR1 signal to a running `dd' process makes it print I/O statistics to standard error and then resume copying.

: $ dd if=/dev/zero of=/dev/null& pid=$!
$ kill -USR1 $pid; sleep 1; kill $pid
: 18335302&subreq=y&showman=0 records in 18335302&subreq=y&showman=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 bugs to <bug-coreutils@gnu.org>.

COPYRIGHT

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.

This document was created by man2html, using the manual pages.
Time: 16:06:49 GMT, August 20, 2008

DD