I've looked at the gnuplot mode 2014 github site
<https://github.com/bruceravel/gnuplot-mode/issues> -- and no issues seem
to have been addressed by the owner in recent years. Will try to debug
myself.

On Tue, Apr 30, 2019 at 1:09 AM Fraga, Eric <e.fraga@ucl.ac.uk> wrote:

> Thanks for the long explanation.  I am using the 2014 version of
> gnuplot-mode and gnuplot 5.2.
>
> gnuplot-mode has a customizable variable, gnuplot-program, which
> specifies which command to execute to start gnuplot.  The default value
> for this variable, at least in the 2014 version, is simply "gnuplot" so
> it will pick up the default gnuplot on Linux (if there is more than one
> version installed, I imagine that /etc/alternatives will be used to
> identify the default).
>
> If you think the wrong gnuplot is being picked up, maybe customize this
> variable?  What do you get if you simply invoke "M-x run-gnuplot"?
>
> --
> Eric S Fraga via Emacs 27.0.50, Org release_9.2.3-327-g3375f0
>