server-eval-at

server-eval-at is a compiled Lisp function in `server.el'.

(server-eval-at SERVER FORM)

Contact the Emacs server named SERVER and evaluate FORM there.
Returns the result of the evaluation, or signals an error if it
cannot contact the specified server. For example:
(server-eval-at "server" '(emacs-pid))
returns the process ID of the Emacs instance running "server".