Re: How to communicate with a running external process with given PID?

[Thorsten Jolitz <tjolitz@gmail.com>]

Kevin Rodgers <kevin.d.rodgers@gmail.com> writes:

> On 7/20/13 3:06 AM, Thorsten Jolitz wrote:
>> say I want to call another program (more exactly, another Lisp program
>> that is not Emacs Lisp) from an Emacs Lisp program.

[snip]

>> I just want to use a running external process with a given PID in a
>> similar way I would use (a)synchronous processes created from Emacs
>> with `call-process' or `start-process'. How can I do that?
>
> Since Emacs did not start the external process, it does not have
> access to its standard input stream -- unless your OS provides a way
> to do that (e.g. via a special /dev file).
>
> How would you communicate with the external process, from any other
> program?

I don't know, and I interpreted the responses so far to my post as "it
is impossible, only 'kill' can access the running external process with
given PID" - but kill sends signals, no command-strings or so. 

So when suggestions arrive like 'use plain socket communication' I'm
still curious if there is a 'magic hack' to achieve that, given that the
external process is NO Emacs subprocess and already running.

-- 
cheers,
Thorsten