Hello World in go

package main

import (
	"bufio"
	"flag"
	"fmt"
	"os"
	"os/user"
	"strings"
	"time"
)

var (
	Salutations = []string{"Hello $@", "Bye $@", "See you later", "Hi $@, how are you?", "The time is $T"}
)

func main() {

	echo := flag.Bool("echo", false, "echo from standard input")
	help := flag.Bool("help", false, "help description")
	dmenu := flag.Bool("dmenu", false, "output list of salutations for dmenu")
	salutation := flag.Bool("salutation", false, "use input as salutation template")

	flag.Parse()

	/* show usage and help */
	if *help {

		fmt.Fprintf(os.Stdout, "example usage :-\n")
		fmt.Fprintf(os.Stdout, "\t./hello | ./hello -echo\n")
		fmt.Fprintf(os.Stdout, "\tusing dmenu to choose saluation, ./hello -dmenu | dmenu -p \"salutation\" | ./hello -salutation\n\n")

		flag.VisitAll(func(f *flag.Flag) {

			fmt.Fprintf(os.Stdout, "%6s | %s\n", f.Name, f.Usage)
		})
		os.Exit(0)
	}

	/* generate dmenu list */
	if *dmenu {
		for _, sal := range Salutations {
			fmt.Fprintf(os.Stdout, sal+"\n")
		}
		os.Exit(0)
	}

	/* create a simple template function, we only template for
	 * username $@, stdin $_, and current time $T */
	template := func(t string, u *user.User, now time.Time) string {

		if strings.Contains(t, "$@") {
			t = strings.Replace(t, "$@", u.Name, -1)
		}

		if strings.Contains(t, "$T") {
			t = strings.Replace(t, "$T", now.Format("15:04"), -1)
		}

		return t
	}

	snip := func(in string) string {
		if in[len(in)-1] == '\n' {
			return in[:len(in)-1]
		}
		return in
	}

	/* gather information about the current user */
	whoami, err := user.Current()
	if err != nil {
		goto hello
	}

	/* if in echo mode then read-in on standard input */
	if *echo {

		reader := bufio.NewReader(os.Stdin)
		input, err := reader.ReadString('\n')
		if err != nil {
			goto hello
		}

		fmt.Fprintf(os.Stdout, "[%s] says %q\n", whoami.Username, snip(input))
		os.Exit(0)
	}

	if *salutation {

		reader := bufio.NewReader(os.Stdin)
		input, err := reader.ReadString('\n')
		if err != nil {
			goto hello
		}

		fmt.Fprintf(os.Stdout, "%s\n", template(snip(input), whoami, time.Now()))
		os.Exit(0)
	}

	/* otherwise say hello to the user */
	fmt.Fprintf(os.Stdout, "%s\n", template(Salutations[0], whoami, time.Now()))
	os.Exit(0)

	/* this is generally bad form -- but it's a nice way
	 * to handle errors and give an expected reply.
	 */
hello:
	fmt.Fprintf(os.Stdout, "Hello there\n")
}

./hello -dmenu | dmenu -p "salutation" | ./hello -salutation
[select "Hi $@, how are you?" from dmenu]

Hi Alice, how are you?