Re: Feature request: new function start-remote-process

[Michael Albinus <michael.albinus@gmx.de>]

Richard Stallman <rms@gnu.org> writes:

>     > start-remote-process shall behave similar: if default-directory points
>     > to a remote host, the corresponding program shall be executed there.
>
>     Looks like nobody objects. I'll install it next days in the trunk,
>     unless there is a veto.
>
> But...how is it possible to do run a program on a remote host?
> In general, there is no way, right?

Why not? Tramp must call programs on a remote host permanently. It opens
a new buffer by

(start-process "name" tramp-buffer "ssh" host "-l" user)

Then it sends the program to that process, and reads the result in the
buffer.

A program can be regarded as the "basename" of an absolute file name.

(let ((default-directory "/ssh:user@host:"))
  (start-remote-process "example" "*scratch*" "hostname"))

does work in my implementation. It must be specified how the program
"hostname" is found. We've discussed shortly two years ago, how to
use `executable-find' and `exec-path' for that, with no result.

For the time being, I would propose that the search path for a program
on a remote host shall be the result of `getconf PATH` on the remote
host (that's what Tramp 2.1 does by default). If a program is not found
in that path, it could be called by its absolute file name:

(let ((default-directory "/ssh:user@host:"))
  (start-remote-process "example" "*scratch*" "/bin/hostname"))

However, there must be a better mechanism to define exec-path for remote
hosts. Tramp has an own, proprietary mechanism (see tramp-remote-path);
this needs to be generalized.

Best regards, Michael.magdalene