[SOLVED] Confirming device contains only zeros

wdssharp · 12-07-2021, 01:18 AM

I have wiped several hard drives with either dc3dd or dcfldd and would like to check if they are indeed wiped with zeros. I would like to not scroll through page after page of zeros, but only see the first line and any line thereafter with data other than zero. My commands were:
sudo dc3dd hwipe=/dev/sda hash=md5
sudo dcfldd if=/dev/zero of=/dev/sda bs=8k

Would using xxd or hexdump confirm the above?

syg00 · 12-07-2021, 01:26 AM

From memory "hd -C ..." should do the job. Will take a while - maybe test on a subset first.

shruggy · 12-07-2021, 02:29 AM

Quote:

Originally Posted by wdssharp

but only see the first line and any line thereafter with data other than zero.

Both od and hexdump do this by default. xxd only when -a/-autoskip is specified.

wdssharp · 12-07-2021, 06:05 AM

sudo xxd -a /dev/sda

shruggy · 12-07-2021, 06:08 AM

Exactly.

pan64 · 12-07-2021, 06:12 AM

grep -qP '[^\x00]' /dev/sda
https://askubuntu.com/questions/1065...ytes-in-a-file