WRIP COMMAND

#shred -vfz -n 10 /dev/sda

-v: show progress

-f: change permissions to allow writing if necessary

-z: add a final overwrite with zeros to hide shredding

-n: overwrite N times instead of the default (3)

So this would overwrite /dev/sda5 ten times.

You can also use shred for RAID partitions, e.g.