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 (default: 512); overrides ibs and obs
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 |
(or oseek=N) skip N obs-sized output blocks |
|||
|
skip=N |
(or iseek=N) skip N ibs-sized input blocks |
status=LEVEL
The LEVEL of information to print to stderr; ’none’ suppresses everything but error messages, ’noxfer’ suppresses the final transfer statistics, ’progress’ shows periodic transfer statistics
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, R, Q. Binary prefixes can be used, too: KiB=K, MiB=M, and so on. If N ends in ’B’, it counts bytes not blocks.
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 all-NUL output 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
Request to drop cache. See also oflag=sync
|
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.
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: <https://www.gnu.org/software/coreutils/>;
Report any translation bugs to
<https://translationproject.org/team/>;
COPYRIGHT
Copyright
© 2023 Free Software Foundation, Inc. License GPLv3+:
GNU GPL version 3 or later
<https://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
<https://www.gnu.org/software/coreutils/dd>;
or available locally via: info '(coreutils) dd
invocation'