Michael van Elst <mlel...@serpens.de> wrote: > On Fri, Sep 15, 2017 at 05:52:10AM -0400, William D. Jones wrote: > >> ``` >> rpi-ptrain$ ls -l /dev/plcom0 >> crw------- 1 uucp wheel 93, 0 Jun 25 12:49 /dev/plcom0 >> rpi-ptrain$ ls -l /dev/ttyU0 >> crw------- 1 wjones tty 74, 0 Jun 25 17:42 /dev/ttyU0 > >> Why are they different, and why do I own `ttyU0` (I don't think NetBSD >> dynamically creates/alters device nodes)? > > plcom0 still has the default ownership, which is the uucp account for > the original communication protocol ("Unix-to-Unix-CoPy"). > > ttyU0 was running getty, you logged in and the login process passes > ownership of the tty to you. Ownership is reset when you log out. > > The command 'write' is a very traditional way to send messages to > other users on the system by just writing text to their tty. The > command 'mesg' is used to grant and revoke write access for others. > > You also need ownership to change tty settings, without this you > couldn't run e.g. a screen editor like vi.
BTW, shouldn't dial-out devices be owned by "dialer" and group-writable? ISTR this was broken when uucp was removed from the base. I thought we had a PR for this, but I can't seem to find it. -uwe