Warning & Disclaimer: dd is a low level tool. if you are not familiar with it please do NOT use it. If wrongly used it can wipe off all your data. Always run or play with such commands on TEST Machines first. If you follow this post , you accept you are doing it at your own risk.
dd if=FILE1 of=FILE2
pkill -USER1 dd
To see output being refreshed continuosly:
watch -n 10 pkill -USR1 dd
pv FILE1 | dd of=FILE2
EXAMPLE: sudo pv /dev/sde3 |dd of= /tmp/mybackup.img
WHERE: /dev/sde3 is the data partition (the input) on my usb drive
AND /tmp/mybackup.img is the output (the backup)
I have taken this post & modified a bit to make it more clear from Robert’s Blog.