Re: check if another emacs instance is running

[Juanma Barranquero]

>  Use some external utility to list current processes e.g.
>  (when (< 1 (string-to-number
>              (shell-command-to-string "ps -A |grep -c emacs23")))
>    (message "ok"))
>  ;; but this is system-specific.

On Emacs 23, you can use `list-system-processes' to obtain a list of
process PIDs, and `process-attributes' to get info for each one,
including the process name, etc.

    Juanma