creation of logfile only if logging is enabled

mqtt_sniffer.py

@@ -9,6 +9,7 @@ import time
 
 VERSION = "0.1.0"
 STARTTIME = time.time()
+logfile = None
 
 HELPTEXT = """
 F1: Get this help message
@@ -48,6 +49,8 @@ def rx_mqtt(mc, userdata, message):
     if match:
         print("%9.04f::%75s::%s" % (ts, message.topic, data))
         if my_bb.get_entry('log2file'):
+            if logfile is None:
+                logfile = open('mqtt_sniffer.log', 'w')
             logfile.write("%9.04f::%s::%s\n" % (ts, message.topic, data))
             logfile.flush()
 
@@ -76,7 +79,7 @@ if __name__ == "__main__":
     my_bb.add_entry('msg_re', 2, my_bb.FUNC_TEXT, label='[F2] Filter', default=args.topicfilter)
     my_bb.add_entry('quit', 12, my_bb.FUNC_QUIT, "Quit", label='[F12]', right=True)
     my_bb.add_entry('log2file', 9, my_bb.FUNC_BOOL, label='[F9] Log2File', default=args.logtofile, right=True)
-    with open('mqtt_sniffer.log', 'w') as logfile:
-        mc = mqtt.mqtt_client("mqtt_sniffer", args.hostname, port=args.port, username=args.username, password=password)
-        mc.add_callback("#", rx_mqtt)
-        my_bb.run()
+
+    mc = mqtt.mqtt_client("mqtt_sniffer", args.hostname, port=args.port, username=args.username, password=password)
+    mc.add_callback("#", rx_mqtt)
+    my_bb.run()