iocopy.go

//create a file `file-01.txt` in the same directory with some content to get started
package main

import (
	"fmt"
	"io"
	"os"
)

func main() {
	f, err := os.Open("file-01.txt")
	if err != nil {
		panic(err)
	}
	defer f.Close()

	f2, err := os.Create("file-02.txt")
	if err != nil {
		panic(err)
	}
	defer f2.Close()

	n, err := io.Copy(f2, f)
	if err != nil {
		panic(err)
	}
	fmt.Println("bytes written", n)
}