[otns_main] cmdline arguments help string rephrased for clarity.

otns_main/otns_main.go

@@ -101,9 +101,9 @@ func parseArgs() {
 	flag.StringVar(&args.WatchLevel, "watch", "off", "set default watch (display) level for new nodes: trace, debug, info, note, warn, error, off.")
 	flag.BoolVar(&args.OpenWeb, "web", true, "open web visualization")
 	flag.BoolVar(&args.Realtime, "realtime", false, "use real-time mode (forced speed=1 and autogo)")
-	flag.StringVar(&args.ListenAddr, "listen", fmt.Sprintf("localhost:%d", InitialDispatcherPort), "specify UDP listen address and port-base")
+	flag.StringVar(&args.ListenAddr, "listen", fmt.Sprintf("localhost:%d", InitialDispatcherPort), "specify TCP/UDP host and port base value for web-GUI/RPC. Recommended ports are 9000, 9010, 9020, etc.")
 	flag.BoolVar(&args.DumpPackets, "dump-packets", false, "dump packets")
-	flag.StringVar(&args.PcapType, "pcap", pcap.FrameTypeWpanStr, "PCAP file type: 'off', 'wpan', or 'wpan-tap' (name is \"current.pcap\")")
+	flag.StringVar(&args.PcapType, "pcap", pcap.FrameTypeWpanStr, "PCAP file type: 'off', 'wpan', or 'wpan-tap'. PCAP is saved to file 'current.pcap'.")
 	flag.BoolVar(&args.NoReplay, "no-replay", false, "do not generate Replay file (named \"otns_?.replay\")")
 	flag.Int64Var(&args.RandomSeed, "seed", 0, "set specific random-seed value (for reproducability)")
 	flag.BoolVar(&args.PhyTxStats, "phy-tx-stats", false, "generate PHY Tx statistics CSV file")