Virsion flag logic is added.

main.go

@@ -6,9 +6,42 @@ import (
 	"os"
 	"os/exec"
 )
-//?
+
+const warning = "//WARNING! DO NOT EDIT THIS FILE BY HAND. IT IS AUTO GENERATED.\n"
+
 const header = "package main\nconst gitVersion = \""
 
+const code = `
+import (
+	"fmt"
+	"os"
+
+	"github.com/spf13/pflag"
+)
+
+func init() {
+	pflag.ErrHelp = nil
+	versionFlagSet := pflag.NewFlagSet("version", pflag.ContinueOnError)
+	versionFlagSet.ParseErrorsWhitelist.UnknownFlags = true
+	versionFlagSet.SetOutput(nil)
+
+	versionIsAsked := versionFlagSet.BoolP("version", "v", false, "Prints version of this application.")
+	versionFlagSet.BoolP("help", "h", false, "") // This line is needed to supress (redefine) built-in help flag.
+
+	err := versionFlagSet.Parse(os.Args)
+	if err != nil {
+		fmt.Println(err)
+		os.Exit(1)
+	}
+
+	if *versionIsAsked {
+		fmt.Println("Simple Serial version: " + Value)
+		os.Exit(0)
+	}
+}
+
+`
+
 func main() {
 	cmd := exec.Command("git", "describe", "--tags", "--abbrev=0")
 	out, err := cmd.Output()
@@ -18,7 +51,7 @@ func main() {
 	}
 	version := string(out)
 	version = version[:len(version)-1]
-	content := header + version + "\""
+	content := warning + header + version + "\"" + code
 
 	ioutil.WriteFile("version.go", []byte(content), 0644)
 }