Hello Roland,
Yes, thank you, I know all these facts and I have successfully tried them out. The kissattach program, however, is needed to connect the ptty. Unfortunately kissattach is not very systemd friendly because it does not store its pid into a file, so it can be controlled. Yes this could be fixed by fixing kissattach, and yes the issue can be worked around. "soundmodem" on the other hand does not need kissatach because it uses the kernel mkiss interface.
There are several examples of how to integrate Direwolf into a systemd unit and service but that's more of a Linux distribution topic more than purely a Direwolf issue . See Basil's follow up email on this thread for some examples and there are others in the groups.io archives.
What I mean is that you can set up, say 1200Bd and 9600Bd on the same radio link at the same time (well almost), i.e. you can work two different stations each connected at its speed of the same radio link. To my knowledge this is a feature that is planned for direwolf, but not available today, correct?
It's been a long time since I've used Thomas Sailer's soundmodem and I don't remember if it supported such a configuration but I would be surprised if it did. Even if it does, it's decode performance is so low (especially on 9600bps FSK), why would it really matter?
Btw.. if you're looking for alternatives to Direwolf that are actively maintained and have good to excellent decode rates, you might want to check out John Weisman's soundmodem which is based on Andy Kopanchuk UZ7HO's Windows soundmodem:
https://www.cantab.net/users/john.wiseman/Documents/QtSoundModem.html --David KI6ZHD