On 2020-02-09 14:27, Thomas Schmitt wrote:
dd if=/dev/zero bs=512 count=2 of=/dev/sdc
When I want to zero-fill a USB flash drive:
1 1M = 1024*1024 byte blocks read and write much faster than 512 byte
blocks.
2. I zero-fill the whole flash drive (by omitting 'count'):
a. Get rid of any leftovers from any source, known or unknown.
b. Verifies fast.
c. Once I have written an image:
i. I know that non-zero bytes came from the image.
ii. If I take an image later, zeroes compress nicely.
3. Debian provides human-readable /dev/disk/by-id device nodes. Using
them reduces the chance that I will blow away the wrong drive.
So, I would suggest the following (adjust device node to suit):
# time dd if=/dev/zero bs=1M
of=/dev/disk/by-id/usb-SanDisk_Ultra_Fit_xxxxxxxxxxxxxxxxxxxx-0\:0
Optional:
4. 'status=progress'
5. 'time dd ....'
David