Add main file and calculate config file path

main.go

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"github.com/cep21/xdgbasedir"
+)
+
+type args struct {
+	ConfigFile *string
+}
+
+func main() {
+	args := args{
+		ConfigFile: flag.String(
+			"config", getDefaultConfigName(), "Usage about option",
+		),
+	}
+
+	flag.Parse()
+
+	fmt.Println(*args.ConfigFile)
+}
+
+func getDefaultConfigName() string {
+	configHome, _ := xdgbasedir.ConfigHomeDirectory()
+
+	return fmt.Sprintf("%s/promptkit.toml", configHome)
+}