Re: Getty on USB serial port

[uwe%stderr.spb.ru@localhost (Valery Ushakov)]

Michael van Elst <mlelstv%serpens.de@localhost> 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