Commanding remote emacs (was Re: X- and non-X-frames in same emacs?)

[Tapani Tarvainen <tt+gn20030130T143401@it.jyu.fi>]

Eli Zaretskii <eliz@is.elta.co.il> writes:

> On 30 Jan 2003, Tapani Tarvainen wrote:
> 
> > Is it possible to have an X frame and a non-X frame in same emacs
> > simultaneously?
> 
> No, I don't think the current Emacs code supports that.  Sorry.

I was afraid of that. :-(

The next question is, what would be the easiest way to pass
commands to an emacs whose only (or all) frame(s) are on
a remote display?
I.e., I connect to a remote box with ssh and there's an emacs
running and I want to send it a command to execute
(I'm thinking of make-frame-on-display, if it isn't obvious).

It should not be impossible to set up emacs so that it reads a
specific file or pipe either every few minutes with a timer or
whenever some signal is received and evaluates whatever it
finds there, or perhaps rather uses its contents as part of a
predefined command. It would not be entirely trivial, however,
and as yet I've no idea how to trap signals with emacs or how
to set up such a timer; I would be grateful of any suggestions
on which would be easier or where to look for code that I
could use as example.

Of course, since I have access to X in the remote I could in
principle use X protocol to send keystrokes to it. I'm afraid
my X programming skills aren't up to that, but I'm open to
suggestions if there's a reasonably simple way to do it.

One approach would be using gdb to grab to the running
emacs process, but feeding it the desired command that
way doesn't sound easy either.

Comments, anyone?

Should I forget this and install XEmacs instead (if it indeed
can handle X- and non-X-frames simultaneously, so that I could
start it under screen without X and create X frames from there)?

-- 
Tapani Tarvainen