README and code

README.txt

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+LuaCmd Minetest Mod
+===================
+
+This mod adds the useful debugging command /lua which executes its parameter
+string as a Lua chunk, as if it were being run in the body of a function inside
+some mod file.  Errors are reported to the player via in-game chat, as is
+anything sent to the print() function.  For example, entering the command:
+
+   ]/lua print("Hello self");
+
+will result in the following output in the in-game chat console:
+
+   issued command: /lua print("Hello self");
+   Hello self
+
+whereas entering the (erroneous) command:
+
+   ]/lua ^
+
+will result in the following output:
+
+   issued command: /lua ^
+   Server -!- ERROR: [string "/lua command"]:1: unexpected symbol near '^'
+
+A slightly more useful example might be the command (note: though shown here
+with line wrapping, it must actually be done on a single line):
+
+   /lua for _, player in ipairs(minetest.get_connected_players()) do
+        print(player:get_player_name()); end
+
+Any player executing this command must have the new "lua" permission, as it is
+about the most dangerous thing you could allow a player to do.  Also not
+recommended for public servers.  Use at your own risk!
+
+Required Minetest Version: (tested in 0.4.9)
+
+Dependencies: (none)
+
+Commands: /lua <luaStatement>
+
+Privileges: lua
+
+Git Repo: https://github.com/prestidigitator/minetest-mod-luacmd
+
+Change History
+--------------
+
+Version 1.0
+
+* Released 2014-07-04
+* First working version
+
+Copyright and Licensing
+-----------------------
+
+All contents are the original creations of the mod author (prestidigitator).
+
+Author: prestidigitator (as registered on forum.minetest.net)
+License: WTFPL (all content)

init.lua

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+local function copyTable(t)
+   if type(t) ~= "table" then return t; end
+   local tc = {};
+   for k, v in pairs(t) do
+      tc[k] = v;
+   end
+   return tc;
+end
+
+minetest.register_privilege(
+   "lua",
+   {
+      description = "Allows use of the /lua chat command for debugging.",
+      give_to_singleplayer = false
+   });
+
+minetest.register_chatcommand(
+   "lua",
+   {
+      params = "<luaStatement>",
+      description = "Executes a lua statement (chunk), for debugging.",
+      privs = { lua = true },
+      func =
+         function(name, param)
+            local cmdFunc, success, errMsg;
+
+            cmdFunc, errMsg = loadstring(param, "/lua command");
+            if not cmdFunc then
+               minetest.chat_send_player(name, "ERROR: "..errMsg);
+               return;
+            end
+
+            local env = copyTable(getfenv(0));
+            env.print =
+               function(...)
+                  minetest.chat_send_player(name, table.concat({...}), false);
+               end;
+
+            setfenv(cmdFunc, env);
+
+            success, errMsg = pcall(cmdFunc);
+            if not success then
+               minetest.chat_send_player(name, "ERROR: "..errMsg);
+            end
+         end
+   });