I am under the impression that sha256sum pings the distro side of things and reads "THEIR" hash file for my .img and gives me that info in a hash-printout in my term.

If so, how I am able to get that info without being connected to the network?

I tried it a few times without the network connected, neither wifi or ethernet. Both times, with different images in different term's, I got a response. It makes me think the command is just reading MY "sha256sum.sha file that downloaded with the image. Maybe it is, either way, seems strange.

Debian 10 buster; 32-bit


  • What gave you that impression? – muru Sep 27 at 6:15
  • @muru I was given the wrong information. – topencrypt Sep 27 at 6:38

sha256sum x.img calculates the SHA-256 checksum of x.img, locally. sha256sum can also verify checksums with the -c option, again locally. There’s no remote connectivity involved.

It’s up to you to either manually compare the output of sha256sum x.img with a published checksum, or download a checksum file and verify that. sha256sum doesn’t know about “official” checksums for anything.

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