How to define and parse positional (non-flag) command-line arguments in Go?

In Go, you can use the flag package to define and parse command-line arguments, both positional and flag arguments. However, the flag package is more focused on flag-style arguments, where you specify the argument name followed by a value using a flag syntax (-name value or --name value).

For positional (non-flag) command-line arguments, you can use the os package to access the command-line arguments directly. Here's an example of how you can define and parse positional arguments in Go:

package main

import (
	"fmt"
	"os"
)

func main() {
	args := os.Args[1:] // Skip the program name (first argument)

	// Check if the expected number of arguments is provided
	if len(args) != 3 {
		fmt.Println("Usage: program <arg1> <arg2> <arg3>")
		return
	}

	arg1 := args[0]
	arg2 := args[1]
	arg3 := args[2]

	// Use the parsed arguments as needed
	fmt.Printf("arg1: %s\n", arg1)
	fmt.Printf("arg2: %s\n", arg2)
	fmt.Printf("arg3: %s\n", arg3)
}

In this example, we use os.Args to access the command-line arguments. We skip the first argument (program name) using os.Args[1:], and then check if the expected number of arguments is provided. If not, we print a usage message and exit.

Assuming the program is compiled and named program, you can run it like this:

$ go run main.go value1 value2 value3

This will output:

arg1: value1
arg2: value2
arg3: value3

Make sure to replace value1, value2, value3 with your desired arguments.