Hackoo, thank you -- that works. There is a bug -- it sees a comma in a filename as a delimiter.
Squashman: I tried this:
hashsum /s /t /a sha256 *.* > hashlist.txt
That worked. Ideally, it would (a) replace the asterisk with nothing, leaving just a single space delimiting the hash from the filename, and (b) add a slash before the name of a subdirectory. Those may be things that I can eventually figure out how to adjust. Neither seems to diminish the desired functionality.
I also tried this:
hashsum /s /t /a sha256 hashsum.bat
That worked too: as with the bulk output, it gave me the code, two spaces, and then the filename, all on a single line.
At present, that looks like exactly what I need. I appreciate both of these quick and useful responses.
This outcome raises two further questions:
(1) I'm not familiar with the differences between this forum (ComputerHope) and DOSTips.com. I got a good answer quickly; I'm satisfied. But for next time, are there differences between the two that should influence my choice of where to post? I'm not a particularly sophisticated batch coder. I did think about posting my question there. Now I wonder whether it's maybe for more advanced DOS users.
(2) It appears that modern GPUs calculate hashes very much faster than CPUs. It also seems that some hash software is designed for GPUs, and some for CPUs. My application for this hash question is security-related. I don't presently have a graphics card. But if I do buy one, I would not like to find that the bad guys are using my GPU to crack codes that seemed to take my CPU a long time. Is HASHSUM.BAT using the CPU? I would assume so. For present purposes, is there anything I should know, or anything I can do, about using HASHSUM.BAT with or without a GPU?