Section 1 · User commands
dd.1
Package: coreutils-common
DD
NAME
SYNOPSIS
DESCRIPTION
AUTHOR
REPORTING BUGS
COPYRIGHT
SEE ALSO
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 © 2024 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’