What does this command mean: 'grep main/source/Sources.gz Release'? Where is the file main/source/Sources.gz?

Question

I'm trying to check the integrity of a source package following this tutorial (https://askubuntu.com/a/509816/978081), however, I don't understand step 4 onward as already described in the title.

4. Compare hashes obtained from sha256sum Sources.gz and grep main/source/Sources.gz Release

Can you help me?

Answer 1

I think that you misunderstands the grep command

grep main/source/Sources.gz Release

The command looks for a text-string "main/source/Sources.gz" in a file called "Release" in current directory.