working on piped messages

mtsenliven.py

@@ -27,24 +27,26 @@ print("Using minetestserver: " + mts)
 print("Using primary_world_path: " + wp)
 print("Using world_name: " + wn)
 print()
+process = None
+try:
     process = subprocess.Popen(
         [mts, '--gameid', game_id, '--worldname', wn],
-    stdout=subprocess.PIPE
+        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
-while True:
-    try:
-        output_original = process.stdout.readline()
-        if output_original == '' and process.poll() is not None:
-            break
-        if output_original:
-            output = output_original.decode("utf-8")
-                    # works on python2 or 3
+
+def print_unique_only(output):
     output_strip = output.strip()
     # (output_original is bytes)
     show_enable = True
@@ -68,6 +70,25 @@ while True:
         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()
+        err_original = process.stderr.readline()
+        if (output_original == '') and \
+           (err_original == '') and \
+           (process.poll() is not None):
+            break
+        if output_original:
+            process_msg(output_original)
+        if err_original:
+            process_msg(err_original)
         rc = process.poll()
     except KeyboardInterrupt:
         break