Device Emulation with a pty?

[Dan Bernstein]

In article <4166 at auspex.auspex.com> guy at auspex.auspex.com (Guy Harris) writes:
> >>  * detect device specific slave side ioctls and reply to them from
> >>    the master side.
> >Look up TIOCPKT and TIOCREMOTE.
> Which will tell you that you can only detect *some* effects from
> slave-side "ioctl"s

Well, yes, but it's also the spot where vendors put in their more
advanced pseudo-tty controls. TIOCUCNTL, for example.

> (I'm not sure what "reply to them from the master
> side" means, but if it means that the process on the master side is to
> be responsible for providing the return code for "ioctl"s or providing
> the return data from "ioctl"s such as TIOCGETP that return data, you
> can't do that, either).

On some systems (such as HP-UX) you can do exactly that. There isn't
much standardization beyond TIOCPKT, but the features do exist. Which is
why I recommended looking them up...

---Dan