to monitor progress

pipe the command into the PV tool
example :  dd command may take many hours to complete.

 pv -tpreb /dev/zero | dd if=/dev/zero of=/dev/null bs=500M count=1000

TODO move this dd block to a seperate note

this demo dd

sudo dd if=/dev/zero of=/dev/null bs=500M count=10

Duplicate data (dd)
from input file (if) of /dev/zero (virtual limitless supply of 0’s)
into output file (of) of /dev/null (virtual sinkhole)
using blocks of 500M size (bs = block size)
and repeat this (count) ten times(01).

there is no need for sudo

/dev/null is a good destination for testing/timing read operations.
/dev/zero is a good source for testing/timing write operations.
Combining this source and destination in one operation doesn’t make much sense.
/dev/zero provides an endless stream of zero bytes when read.
This function is provided by the kernel and does not require allocating memory.
All writes to /dev/null are dropped silently.