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GNU/Linux |
Debian 7.5.0(Wheezy) |
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dd(1) |
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dd − convert and copy a file
dd
[OPERAND]...
dd OPTION
Copy a file,
converting and formatting according to the operands.
bs=BYTES
read and write up to BYTES bytes at a time
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 up to 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:
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ascii |
from EBCDIC to ASCII | ||
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ebcdic |
from ASCII to EBCDIC | ||
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ibm |
from ASCII to alternate EBCDIC | ||
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block |
pad newline−terminated records with spaces to cbs−size |
unblock
replace trailing spaces in cbs−size records with newline
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lcase |
change upper case to lower case | ||
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ucase |
change lower case to upper case | ||
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swab |
swap every pair of input bytes | ||
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sync |
pad every input block with NULs to ibs−size; when used with block or unblock, pad with spaces rather than NULs | ||
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excl |
fail if the output file already exists |
nocreat
do not create the output file
notrunc
do not truncate the output file
noerror
continue after read errors
fdatasync
physically write output file data before finishing
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fsync |
likewise, but also write metadata |
Each FLAG symbol may be:
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append |
append mode (makes sense only for output; conv=notrunc suggested) | ||
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direct |
use direct I/O for data |
directory
fail unless a directory
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dsync |
use synchronized I/O for data |
|||
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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
nocache
discard cached data
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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.
$ 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
Written by Paul Rubin, David MacKenzie, and Stuart Kemp.
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
© 2011 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.
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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dd(1) | |