User Commands D(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 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 multipli-
cative suffixes: xM M, c 1, w 2, b 512, kB 1000, K 1024, MB
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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 ASCI
ebcdic
from ASCI to EBCDIC
ibm from ASCI 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:
append
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append mode (makes sense only for output; conv=notrunc
suggested)
direct
use direct I/O for data
directory fail unless a directory dsync use syn-
chronized 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 control-
ling terminal from file nofollow do not follow sym-
links
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.
REPORTING BUGS
Report bugs to .
COPYRIGHT
Copyright O 2006 Free Software Foundation, Inc.
This is free software. You may redistribute copies of it
under the terms of the GNU General Public License
. There is NO WAR-
RANTY, 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 dd
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should give you access to the complete manual.
ATRIBUTES
See attributes(5) for descriptions of the following attri-
butes:
ATRIBUTE TYPE ATRIBUTE VALUE
Availability SUNWgnu-coreutils
Interface Stability Uncommitted
NOTES
Source for GNU coreutils is available on
http:/opensolaris.org.
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