working on piped messages

mtsenliven.py

@@ -27,47 +27,68 @@ print("Using minetestserver: " + mts)
 print("Using primary_world_path: " + wp)
 print("Using world_name: " + wn)
 print()
-process = subprocess.Popen(
-    [mts, '--gameid', game_id, '--worldname', wn],
-    stdout=subprocess.PIPE
-)
+process = None
+try:
+    process = subprocess.Popen(
+        [mts, '--gameid', game_id, '--worldname', wn],
+        stdout=subprocess.PIPE,
+        stderr=subprocess.PIPE
+    )
+except:
+    print(mts + " could not be executed. Try installing the "
+          " minetest-server package or compiling from git instructions"
+          " on minetest.net")
+    exit(1)
 msg_flags = ["WARNING[Server]: ", "ACTION[Server]: "]
 msg_lists = {}  # where flag is key
 for flag in msg_flags:
     msg_lists[flag] = []
 # see https://www.endpoint.com/blog/2015/01/28/getting-realtime-output-
 # using-python
+
+def print_unique_only(output):
+    output_strip = output.strip()
+    # (output_original is bytes)
+    show_enable = True
+    found_flag = None
+    f_i = None
+    for flag in msg_flags:
+    # such as '2018-02-06 21:08:06: WARNING[Server]: Deprecated call to get_look_yaw, use get_look_horizontal instead'
+    # or 2018-02-06 21:08:05: ACTION[Server]: [playereffects] Wrote playereffects data into /home/owner/.minetest/worlds/FCAGameAWorld/playereffects.mt.
+        f_i = output.find(flag)
+        if f_i >= 0:
+            found_flag = flag
+            break
+    if found_flag:
+        sub_msg = output[f_i+len(flag):].strip()
+        if sub_msg in msg_lists[found_flag]:
+            show_enable = False
+        else:
+            msg_lists[found_flag].append(sub_msg)
+    if show_enable:
+        print(output_strip)
+        if found_flag is not None:
+            print("[ mtsenliven.py ] INFO: this is the last"
+                  " time the message above will be shown")
+
+def process_msg(bstring):
+    output = output_original.decode("utf-8")
+            # works on python2 or 3
+    print_unique_only(output)
+
+
 while True:
     try:
         output_original = process.stdout.readline()
-        if output_original == '' and process.poll() is not None:
+        err_original = process.stderr.readline()
+        if (output_original == '') and \
+           (err_original == '') and \
+           (process.poll() is not None):
             break
         if output_original:
-            output = output_original.decode("utf-8")
-                    # works on python2 or 3
-            output_strip = output.strip()
-            # (output_original is bytes)
-            show_enable = True
-            found_flag = None
-            f_i = None
-            for flag in msg_flags:
-            # such as '2018-02-06 21:08:06: WARNING[Server]: Deprecated call to get_look_yaw, use get_look_horizontal instead'
-            # or 2018-02-06 21:08:05: ACTION[Server]: [playereffects] Wrote playereffects data into /home/owner/.minetest/worlds/FCAGameAWorld/playereffects.mt.
-                f_i = output.find(flag)
-                if f_i >= 0:
-                    found_flag = flag
-                    break
-            if found_flag:
-                sub_msg = output[f_i+len(flag):].strip()
-                if sub_msg in msg_lists[found_flag]:
-                    show_enable = False
-                else:
-                    msg_lists[found_flag].append(sub_msg)
-            if show_enable:
-                print(output_strip)
-                if found_flag is not None:
-                    print("[ mtsenliven.py ] INFO: this is the last"
-                          " time the message above will be shown")
+            process_msg(output_original)
+        if err_original:
+            process_msg(err_original)
         rc = process.poll()
     except KeyboardInterrupt:
         break