Codex

DD

Section: User Commands (1)

Updated: March 2015

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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
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=N
copy only N 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=N
skip N obs-sized blocks at start of output:
skip=N
skip N ibs-sized blocks at start of input:
status=WHICH
WHICH info to suppress outputting to stderr; 'noxfer' suppresses transfer stats, 'none' suppresses all:

N 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:
ucase
change lower case to upper case:
sparse
try to seek rather than write the output for NUL input blocks:
swab
swap every pair of input bytes:
sync
pad every input block with NULs to ibs-size; when used with block or unblock, pad with spaces rather than NULs:
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:
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:
nocache
discard cached data:
noctty
do not assign controlling terminal from file:
nofollow
do not follow symlinks:
count_bytes
treat 'count=N' as a byte count (iflag only):
skip_bytes
treat 'skip=N' as a byte count (iflag only):
seek_bytes
treat 'seek=N' as a byte count (oflag only):

Sending a USR1 signal to a running 'dd' process makes it print I/O statistics to standard error and then resume copying.

:
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

GNU coreutils online help: <http://www.gnu.org/software/coreutils/>

Report dd translation bugs to <http://translationproject.org/team/>

COPYRIGHT

Copyright © 2014 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

Full documentation at: <http://www.gnu.org/software/coreutils/dd>

or available locally via: info '(coreutils) dd invocation'


Index

NAME

SYNOPSIS

DESCRIPTION

AUTHOR

REPORTING BUGS

COPYRIGHT

SEE ALSO


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