Search⌘ K
Home
Courses
Write Professional Command-line Programs in Go

Working with Cobra - The Sub-commands

Explore how to define sub-commands in Go command-line programs using the Cobra library. Understand how to implement argument parsing, create Run functions for commands, and wire sub-commands to the root command using init functions. This lesson helps you structure CLI applications effectively with Cobra.

We'll cover the following...

The add subcommand

Cobra is all about defining sub-commands. Let’s start with the add subcommand. It will be defined in the cmd/add.go file:

package cmd

import (
	"fmt"
	"gigi/calc/pkg/calc"
	"github.com/spf13/cobra"
	"strconv"
)

var check bool

var addCmd = &cobra.Command{
	Use:   "add",
	Short: "Add two integers",
	Long:  `Add two integers a and b; result = a + b`,
	Args:  cobra.ExactArgs(2),
	Run: func(cmd *cobra.Command, args []string) {
		var a, b int
		var err error
		a, err = strconv.Atoi(args[0])
		if err != nil {
			panic("Arguments to `add` must be integers")
		}
		b, err = strconv.Atoi(args[1])
		if err != nil {
			panic("Arguments to `add` must be integers")
		}

		result := calc.Add(a, b, check)
		fmt.Println(result)
	},
}

Let’s review its Run function. The signature ...