Need to securely wipe a HDD?
This is the only command you'll need
shred -vfz -n 20 /dev/sdb
The shred command is not exclusive to Kali, you will find it in any distro that has the GNU core utilities
-v - verbose, shows all those progress lines
-f - ensures that permission issues will not stop deletion
-z - 0s - write a final line of 0s afterward to hide the shredded data
-n - number of passes to make, in this case 50 + 1 (from the z) = 51passes
/dev/sdb - disk location
Note: This command can be used for individual files as well.