add glog flush to write the output to a file (#329)

* add glog flush to write the output to a file

* add glog flush before exit on error and fix code comment

cmd/root.go

@@ -74,8 +74,12 @@ func Execute() {
 
 	if err := RootCmd.Execute(); err != nil {
 		fmt.Println(err)
+		// flush before exit non-zero
+		glog.Flush()
 		os.Exit(-1)
 	}
+	// flush before exit
+	glog.Flush()
 }
 
 func init() {

cmd/util.go

@@ -35,6 +35,8 @@ func init() {
 
 func exitWithError(err error) {
 	fmt.Fprintf(os.Stderr, "\n%v\n", err)
+	// flush before exit non-zero
+	glog.Flush()
 	os.Exit(1)
 }