Dd

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 skip N obs-sized blocks at start of output

skip=N skip N ibs-sized blocks at start of input

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.

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

Dd

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