Useful DD Commands

dd if=/dev/sda | tee >(dd of=/dev/sdb) | dd of=/dev/sdc

If you have some drive imaging to do, you can boot into any liveCD and use a commodity machine. The drives will be written in parallel.

To improve efficiency, specify a larger block size in dd:

dd if=/dev/sda bs=64k | tee >(dd of=/dev/sdb bs=64k) | dd of=/dev/sdc bs=64k

To image more drives, insert them as additional arguments to tee:

dd if=/dev/sda | tee >(dd of=/dev/sdb) >(dd of=/dev/sdc) >(dd of=/dev/sdd) | dd of=/dev/sde

sudo dd if=/dev/zero of=/swapfile bs=1024 count=1024000;sudo mkswap /swapfile; sudo swapon /swapfile

Create a temporary file that acts as swap space. In this example it’s a 1GB file at the root of the file system. This additional capacity is added to the existing swap space.

sudo dd if=/dev/sda of=/media/disk/backup/sda.backup

This will create an exact duplicate image of your hard drive that you can then restore by simply reversing the “if” & “of” locations.

sudo dd if=/media/disk/backup/sda.backup of=/dev/sda

Alternatively, you can use an SSH connection to do your backups:

dd if=/dev/sda | ssh user@ssh.server.com dd of=~/backup/sda.backup

dd bs=1k if=image.nrg of=image.iso skip=300

This line removes the 300k header from a Nero image file converting it to ISO format

while :;do killall -USR1 dd;sleep 1;done

every 1sec sends DD the USR1 signal which causes DD to print its progress.

killall -USR1 dd

if you need see progress of long dd command, enter subj on other console

dd if=/dev/cdrom of=whatever.iso

dd if=/dev/zero | pv | dd of=/dev/null

need pv (pipe view)

sudo dd if=/dev/hda1 of=/dev/hdb2

This command clone the first partition of the primary master IDE drive to the second partition of the primary slave IDE drive (!!! back up all data before trying anything like this !!!)

dd if=/dev/zero bs=4096 count=1048576 | ssh user@host.tld 'cat > /dev/null'

The above command will send 4GB of data from one host to the next over the network, without consuming any unnecessary disk on either the client nor the host. This is a quick and dirty way to benchmark network speed without wasting any time or disk space. Of course, change the byte size and count as necessary.

This command also doesn’t rely on any extra 3rd party utilities, as dd, ssh, cat, /dev/zero and /dev/null are installed on all major Unix-like operating systems.

dd if=/dev/sda | gzip -c | ssh user@ip 'dd of=/mnt/backups/sda.dd'