dd command

The main purpose of the Unix dd command is to copy data from one device to other; the command stands for device dump. A dd command transfers raw data among devices.

Syntax

dd [OPTION]...

This command copies a file, formats and converts according to the given options.

Options:

if=FILE                       It read from FILE instead of stdin

of=FILE                     It write to FILE instead of stdout

 bs=BYTES                 it force ibs=BYTES and obs=BYTES

ibs=BYTES                 it read BYTES bytes at a time

obs=BYTES                it write BYTES bytes at a time

Practice

Let consider the given example describes how to copy the contents of one floppy disk to another, using /tmp as a temporary storage area.

The source disk is inserted in the drive, and the given command entered:

#dd if=/dev/fd0 of=/tmp/tmpfile bs=50k

28+1 records in

28+1 records out

In the given example dd is the command that is used to copy from one disk to another disk. Numbers of partial and full blocks read in the current input block size.ie bs=50k 28+1 records out means. Numbers of partial and full blocks are written in the current output block size.

Where if=FILE

read from FILE instead of stdin of=FILE

write to FILE instead of stdout

bs=BYTES

force ibs=BYTES and obs=BYTES