add -version support to beaconchain app

Signed-off-by: Leo Chen <leo@harmony.one>

go_executable_build.sh

@@ -2,6 +2,7 @@
 declare -A SRC
 SRC[benchmark]=benchmark.go
 SRC[txgen]=client/txgen/main.go
+SRC[beacon]=runbeacon/run-beacon.go
 
 BINDIR=bin
 BUCKET=unique-bucket-bin

runbeacon/run-beacon.go

@@ -2,15 +2,37 @@ package main
 
 import (
 	"flag"
+	"fmt"
+	"os"
+	"path"
 
 	"github.com/harmony-one/harmony/beaconchain"
 )
 
+var (
+	version string
+	builtBy string
+	builtAt string
+	commit  string
+)
+
+func printVersion(me string) {
+	fmt.Fprintf(os.Stderr, "Harmony (C) 2018. %v, version %v-%v (%v %v)\n", path.Base(me), version, commit, builtBy, builtAt)
+	os.Exit(0)
+}
+
 func main() {
 	numShards := flag.Int("numShards", 1, "number of shards of identity chain")
 	ip := flag.String("ip", "127.0.0.1", "ip on which beaconchain listens")
 	port := flag.String("port", "8081", "port on which beaconchain listens")
+	versionFlag := flag.Bool("version", false, "Output version info")
+
 	flag.Parse()
+
+	if *versionFlag {
+		printVersion(os.Args[0])
+	}
+
 	bc := beaconchain.New(*numShards, *ip, *port)
 	bc.StartServer()
 }