dcfldd - Man Page

• Copy a disk to a raw image file and hash the image using SHA256: dcfldd if=/dev/disk_device of=file.img hash=sha256 hashlog=file.hash
• Copy a disk to a raw image file, hashing each 1GB chunk: dcfldd if=/dev/disk_device of=file.img hash=sha512|sha384|sha256|sha1|md5 hashlog=file.hash hashwindow=1G

tldr.sh

dcfldd [OPTION]...

Copy a file, converting and formatting according to the options.

bs=BYTES

force ibs=BYTES and obs=BYTES

cbs=BYTES

convert BYTES bytes at a time

conv=KEYWORDS

convert the file as per the comma separated keyword list

count=BLOCKS

copy only BLOCKS input blocks

ibs=BYTES

read BYTES bytes at a time

if=FILE

read from FILE instead of stdin

obs=BYTES

write BYTES bytes at a time

of=FILE

write to FILE instead of stdout

NOTE: of=FILE may be used several times to write

output to multiple files simultaneously

of:=COMMAND

exec and write output to process COMMAND

seek=BLOCKS

skip BLOCKS obs-sized blocks at start of output

skip=BLOCKS

skip BLOCKS ibs-sized blocks at start of input

pattern=HEX

use the specified binary pattern as input

textpattern=TEXT

use repeating TEXT as input

errlog=FILE

send error messages to FILE as well as stderr

hashwindow=BYTES

perform a hash on every BYTES amount of data

hash=NAME

either md5, sha1, sha256, sha384 or sha512

default algorithm is md5. To select multiple algorithms to run simultaneously enter the names in a comma separated list

hashlog=FILE

send MD5 hash output to FILE instead of stderr

if you are using multiple hash algorithms you can send each to a seperate file using the convention ALGORITHMlog=FILE, for example md5log=FILE1, sha1log=FILE2, etc.

hashlog:=COMMAND

exec and write hashlog to process COMMAND

ALGORITHMlog:=COMMAND also works in the same fashion

hashconv=[before|after]

perform the hashing before or after the conversions

hashformat=FORMAT

display each hashwindow according to FORMAT

the hash format mini-language is described below

totalhashformat=FORMAT

display the total hash value according to FORMAT

status=[on|off]

display a continual status message on stderr

default state is "on"

statusinterval=N

update the status message every N blocks

default value is 256

sizeprobe=[if|of]

determine the size of the input or output file

for use with status messages. (this option gives you a percentage indicator) WARNING: do not use this option against a

tape device.

split=BYTES

write every BYTES amount of data to a new file

This operation applies to any of=FILE that follows

splitformat=TEXT

the file extension format for split operation.

you may use any number of 'a' or 'n' in any combo the default format is "nnn" NOTE: The split and splitformat options take effect

only for output files specified AFTER these options appear in the command line.  Likewise, you may specify these several times for for different output files within the same command line. you may use as many digits in any combination you would like. (e.g. "anaannnaana" would be valid, but quite insane)

vf=FILE

verify that FILE matches the specified input

verifylog=FILE

send verify results to FILE instead of stderr

verifylog:=COMMAND

exec and write verify results to process COMMAND

--help

display this help and exit

--version

output version information and exit

The structure of of FORMAT may contain any valid text and special variables. The built-in variables are used the following format: #variable_name# To pass FORMAT strings to the program from a command line, it may be necessary to surround your FORMAT strings with "quotes." The built-in variables are listed below:

window_start

The beginning byte offset of the hashwindow

window_end

The ending byte offset of the hashwindow

block_start

The beginning block (by input blocksize) of the window

block_end

The ending block (by input blocksize) of the hash window

hash

The hash value

algorithm

The name of the hash algorithm

Written by: dcfldd by Nicholas Harbour, GNU dd by Paul Rubin, David MacKenzie and Stuart Kemp.

Report bugs to <nicholasharbour@yahoo.com>.

Copyright © 1985-2006 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

The full documentation for dcfldd is maintained as a Texinfo manual.  If the info and dcfldd programs are properly installed at your site, the command

info dcfldd

should give you access to the complete manual.

nwipe(1).