Get "save oar" and "save iar" to tell you in a more friendly manner if the filename to save already exists, rather than exception throwing.

Also changes ConsoleUtil.CheckFileExists to CheckFileDoesNotExist() since this is more meaningful in the context, even though it does result in double negatives.

OpenSim/Framework/Console/ConsoleUtil.cs

@@ -27,6 +27,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.IO;
 using System.Linq;
 using System.Reflection;
 using log4net;
@@ -60,6 +61,24 @@ namespace OpenSim.Framework.Console
     
         public const string VectorSeparator = ",";
         public static char[] VectorSeparatorChars = VectorSeparator.ToCharArray();
+
+        /// <summary>
+        /// Check if the given file path exists.
+        /// </summary>
+        /// <remarks>If not, warning is printed to the given console.</remarks>
+        /// <returns>true if the file does not exist, false otherwise.</returns>
+        /// <param name='console'></param>
+        /// <param name='path'></param>
+        public static bool CheckFileDoesNotExist(ICommandConsole console, string path)
+        {
+            if (File.Exists(path))
+            {
+                console.OutputFormat("File {0} already exists.  Please move or remove it.", path);
+                return false;
+            }
+
+            return true;
+        }
     
         /// <summary>
         /// Try to parse a console UUID from the console.