Re: how to compute sha digest of usb stick

["Thomas Schmitt" <scdbackup@gmx.net>]

Hi,

hlyg wrote:
> is it possible to verify usb stick with sha256sum without corresponding iso
> file?

The instructions of
  https://www.debian.org/CD//faq/#verify
for "written optical media" apply to USB sticks, too.

I.e. learn <sector count> and <sector size> from:

  /sbin/isosize -x <device>

Use them to curb the data to the original size of the ISO image and
pipe the stream into the checksum program:

  dd if=<device> count=<sector count> bs=<sector size> | sha256sum


> does live cd in usb stick change after running and using for long time? that
> is, all writes are performed in memory?

I expect that Debian Live itself does not alter the ISO filesystem.

But some EFI implementations and a certain operating system feel
entitled to create files in the EFI System Partition filesystem of the
USB stick, which is actually a data file in the ISO filesystem.
See
  https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1056998
(Best to be read bottom-up as the way to the diagnosis was curvy.)


Have a nice day :)

Thomas