--- a/scripts/ChangeLog
+++ b/scripts/ChangeLog
@@ -1,3 +1,7 @@
+2010-09-13  Ben Abbott <bpabbott@mac.com>
+
+	* plot/private/__gnuplot_has_terminal__.m: New function.
+
 2010-09-13  Jaroslav Hajek  <highegg@gmail.com>
 
 	* general/common_size.m: Partially rewrite using cellindexmat.

--- a/scripts/plot/module.mk
+++ b/scripts/plot/module.mk
@@ -19,6 +19,7 @@
   plot/private/__errplot__.m \
   plot/private/__ezplot__.m \
   plot/private/__ghostscript__.m \
+  plot/private/__gnuplot_has_terminal__.m\
   plot/private/__interp_cube__.m \
   plot/private/__line__.m \
   plot/private/__patch__.m \

new file mode 100644
--- /dev/null
+++ b/scripts/plot/private/__gnuplot_has_terminal__.m
@@ -0,0 +1,62 @@
+## Copyright (C) 2010 Ben Abbott
+## 
+## This program is free software; you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 2 of the License, or
+## (at your option) any later version.
+## 
+## This program is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+## 
+## You should have received a copy of the GNU General Public License
+## along with Octave; see the file COPYING.  If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {@var{has_terminal} =} __gnuplot_has_terminal__ (@var{terminal})
+## Undocumented internal function.
+## @end deftypefn
+
+## Author: Ben Abbott <bpabbott@mac.com>
+## Created: 2010-09-13
+
+function gnuplot_supports_term = __gnuplot_has_terminal__ (term, plot_stream)
+  term = deblank (term);
+  n = find (term == " ", 1);
+  if (! isempty (n))
+    term = term(1:n-1);
+  endif
+  if (__gnuplot_has_feature__ ("variable_GPVAL_TERMINALS"))
+    if (nargin < 2)
+      plot_stream = __gnuplot_open_stream__ (2);
+    endif
+    available_terminals = __gnuplot_get_var__ (plot_stream, "GPVAL_TERMINALS");
+    available_terminals = regexp (available_terminals, "\\b\\w+\\b", "match");
+    if (nargin < 2 && ! isempty (plot_stream))
+      pclose (plot_stream(1));
+      if (numel (plot_stream) > 1)
+        pclose (plot_stream(2));
+      endif
+      if (numel (plot_stream) > 2)
+        waitpid (plot_stream(3));
+      endif
+    endif
+  else
+    ## Gnuplot 4.0 terminals. No new terminals were added until 4.4 which
+    ## allows the list of terminals to be obtained from GPVAL_TERMINALS.
+    available_terminals = {"aifm", "aqua", "canvas", "cgm", "corel", ...
+                           "dumb", "dxf", "eepic", "emf", "epslatex", ...
+                           "epson_180dpi", "fig", "gif", "gnugraph", ...
+                           "gpic", "hp2623A", "hp2648", "hp500c", ...
+                           "hpgl", "hpljii", "hppj", "imagen", "jpeg", ...
+                           "latex", "mf", "mif", "mp", "pbm", "pdf", ...
+                           "pm", "png", "postscript", "pslatex", ...
+                           "pstex", "pstricks", "qms", "regis", "rgip", ...
+                           "svg", "texdraw", "tgif", "tkcanvas", ...
+                           "tpic", "windows", "x11", "xlib", "xterm"};
+  endif
+  gnuplot_supports_term = any (strcmpi (available_terminals, term));
+endfunction
+