# 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 

<unimplemented>
</unimplemented>

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.

### CONV:

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

### FLAG

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

#### count_bytes

treat 'count=N' as a byte count (iflag only)

#### skip_bytes

treat 'skip=N' as a byte count (iflag only)

#### seek_bytes

treat 'seek=N' as a byte count (oflag only)

### SIGNALS

Sending a USR1 signal to a running 'dd' process makes it print I/O statistics to standard error and then resume copying.

### OPTIONS

--help display this help and exit --version output version information and exit

### AUTHOR

Originally Written by Paul Rubin, David MacKenzie, and Stuart Kemp. Clone written _only_ by looking at man page by Efron Licht /// input, output, and encoding