Parse Subcommand Flags in Go

package main

import (
    "flag"
    "fmt"
    "os"
)

func main() {

    // We declare a subcommand using the NewFlagSet function,
    // and proceed to define new flags specific for this subcommand.
    fooCmd := flag.NewFlagSet("foo", flag.ExitOnError)
    fooEnable := fooCmd.Bool("enable", false, "enable")
    fooName := fooCmd.String("name", "", "name")

    // For a different subcommand we can define different supported flags.
    barCmd := flag.NewFlagSet("bar", flag.ExitOnError)
    barLevel := barCmd.Int("level", 0, "level")

    if len(os.Args) < 2 {
        fmt.Println("expected 'foo' or 'bar' subcommands")
        os.Exit(1)
    }

    switch os.Args[1] {

    // For every subcommand, we parse its own flags and have access to trailing positional arguments.
    case "foo":
        fooCmd.Parse(os.Args[2:])
        fmt.Println("subcommand 'foo'")
        fmt.Println("  enable:", *fooEnable)
        fmt.Println("  name:", *fooName)
        fmt.Println("  tail:", fooCmd.Args())
    case "bar":
        barCmd.Parse(os.Args[2:])
        fmt.Println("subcommand 'bar'")
        fmt.Println("  level:", *barLevel)
        fmt.Println("  tail:", barCmd.Args())
    default:
        fmt.Println("expected 'foo' or 'bar' subcommands")
        os.Exit(1)
    }
}