dd

Purpose

Copy blocks of data from standard input to standard output (and optionally convert the data from one format to another).

Syntax

dd option1=value1 option2=value2 option3=value3 ...

Options

if=file reads from the specified file instead of standard input.

of=file writes to the specified file instead of standard output.

ibs=nbytes reads blocks of nbytes bytes at a time.

ibs=nbytes writes blocks of nbytes at a time.

bs=nbytes reads and writes blocks of nbyte bytes at a time.

cbs=nbytes converts nbytes bytes at a time.

skip=nblocks skips nblocks input blocks from the beginning of the input file.

seek=nblocks skips nblocks output blocks in the output file.

count=nblocks copies nblocks blocks from input to output.

conv=code performs conversion; code can be one of following:

ascii converts EBCDIC to ASCII.

ebcdic converts ASCII to EBCDIC.

lcase converts to lowercase.

ucase converts to uppercase.

swab swaps every pair of input bytes.

noerror continues after read errors.

(Note: EBCDIC is a character-encoding format used in IBM mainframes.)

Description

The dd command copies blocks of data from standard input to standard output, optionally converting the data as the copying proceeds. Typically, dd is used to copy data directly from one device to another. For example, you can copy the Linux kernel (/boot/vmlinuz) to a diskette with the following command: dd if=/boot/ vmlinuz of=/dev/fd0