The 'plot' command is not available in batch mode.

Issue a warning and ignore it.

src/frontend/com_plot.c

@@ -7,11 +7,17 @@
 
 #include "com_plot.h"
 
+extern bool ft_batchmode;
 
 /* plot name ... [xl[imit]] xlo xhi] [yl[imit ylo yhi] [vs xname] */
 void
 com_plot(wordlist *wl)
 {
+    if (ft_batchmode) {
+        fprintf(stderr, "\nWarning: command 'plot' is not available during batch simulation, ignored!\n");
+        fprintf(stderr, "    You may use Gnuplot instead.\n\n");
+        return;
+    }
     plotit(wl, NULL, NULL);
 }