Detect secure a clean hard disk.

[Andreas Schockenhoff]

Hi,

i am searching for a small shell script that detects, if the
hard disk is clean.

I will use it for virtual machines. There I create always new clean
virtuell hard disks. I will stop the installation if the hard disk is
not clean. 

I will use it for easy automatic fai-cd testing. To be sure that they do
not destroy any data on real hard disks.

In this case the user will use a hard disk with old data. He can clean
the hard disk with example dd if=/dev/zero of=/dev/sda count=1. And
start again.

The new GUID Partition or EFI ... hard disks seams to have also data in
the first sector of the hard disk?

Better ideas?

regards Andreas Schockenhoff