LinuxGuide.it > Linux Man Page: "dd"

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man page(1) manual page Table of Contents

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 multiplicative suffixes: xM M, c 1, w 2, b 512, kB 1000, K 1024, MB 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 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

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 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 nonblock use non-blocking I/O noatime do not update access time noctty do not assign controlling terminal from file nofollow do not follow symlinks

Sending a USR1 signal to a running â€˜ddâ€™ 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

LinuxGuide.it > Linux Man Page: "dd"

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