Write better mod which write data to a fifo.

mods/track_players/init.lua

@@ -1,9 +1,27 @@
 local time_interval = 1.0
+local fifo_path "/tmp/mt_players_fifo"
+
+function players_data()
+    ps = {}
+    for i, player in ipairs(minetest.get_connected_players()) do
+        local pos = player:getpos()
+        local name = player:get_player_name()
+        local data = {
+            name = pname,
+            x = pos.x,
+            y = pos.y,
+            z = pos.z }
+        table.insert(ps, data)
+    end
+    return minetest.write_json(ps) .. '\n'
+end
 
 function time_interval_func()
-    for _, player in ipairs(minetest.get_connected_players()) do
-        local name = player:get_player_name()
-        minetest.chat_send_player(name, "Hello " .. name)
+    local players = players_data()
+    local fifo = io.open(fifo_path, 'w')
+    if (fifo != nil) then
+        fifo.write(players)
+        fifo:close()
     end
     minetest.after(time_interval, time_interval_func)
 end