do a few

cmd/root.go

@@ -0,0 +1,37 @@
+package cmd
+
+import (
+	"log"
+	"net"
+
+	"github.com/spf13/cobra"
+)
+
+var (
+	ip    net.IP
+	port  uint16
+	proto string
+	v6    bool
+)
+
+var rootCmd = &cobra.Command{
+	Use:   "protohacking",
+	Short: "Protohackers challenge servers",
+	Run: func(cmd *cobra.Command, args []string) {
+		cmd.Help()
+	},
+}
+
+func init() {
+	pflags := rootCmd.PersistentFlags()
+	pflags.Uint16VarP(&port, "port", "p", 8088, "Port to TCP listen on")
+	pflags.IPVarP(&ip, "ip", "i", net.IPv6unspecified, "Address to listen on")
+	pflags.BoolVarP(&v6, "v6", "6", true, "Whether to use IPv6")
+	pflags.StringVar(&proto, "proto", "tcp", "Either tcp or udp")
+}
+
+func Execute() {
+	if err := rootCmd.Execute(); err != nil {
+		log.Fatal("fatal error", "err", err)
+	}
+}