Greet - Urfave — ContextQMD

Being a programmer can be a lonely job. Thankfully by the power of automation that is not the case! Let's create a greeter app to fend off our demons of loneliness!

Start by creating a directory named greet, and within it, add a file, greet.go with the following code in it:

package main

import (
	"fmt"
	"log"
	"os"
	"context"

	"github.com/urfave/cli/v3"
)

func main() {
	cmd := &cli.Command{
		Name:  "greet",
		Usage: "fight the loneliness!",
		Action: func(context.Context, *cli.Command) error {
			fmt.Println("Hello friend!")
			return nil
		},
	}

	if err := cmd.Run(context.Background(), os.Args); err != nil {
		log.Fatal(err)
	}
}

Install our command to the $GOPATH/bin directory:

sh-session

$ go install

Finally run our new command:

sh-session

$ greet
Hello friend!

cli also generates neat help text:

sh-session

$ greet help
NAME:
   greet - fight the loneliness!

USAGE:
   greet [global options]

GLOBAL OPTIONS:
   --help, -h  show help

In general a full help with flags and subcommands would give something like this

NAME:
    greet - fight the loneliness!

USAGE:
    greet [global options] command [command options] [arguments...]

COMMANDS:
    help, h  Shows a list of commands or help for one command

GLOBAL OPTIONS
    --help, -h  show help (default: false)