Introduction #

This article is intented to help you with the copy process of one or multiple files. We’ll start by creating a new package, and call it copy. Our functions will be named respectively File(src, dst string) and Dir(src, dst string) so that we can import our package and just call something like copy.File("file.txt", "file_copy.txt")

Copy a single file #

package copy

import (
	"fmt"
	"io"
	"io/ioutil"
	"os"
	"path"
)

// File copies a single file from src to dst
func File(src, dst string) error {
	var err error
	var srcfd *os.File
	var dstfd *os.File
	var srcinfo os.FileInfo

	if srcfd, err = os.Open(src); err != nil {
		return err
	}
	defer srcfd.Close()

	if dstfd, err = os.Create(dst); err != nil {
		return err
	}
	defer dstfd.Close()

	if _, err = io.Copy(dstfd, srcfd); err != nil {
		return err
	}
	if srcinfo, err = os.Stat(src); err != nil {
		return err
	}
	return os.Chmod(dst, srcinfo.Mode())
}

Copy a directory recursively #

// Dir copies a whole directory recursively
func Dir(src string, dst string) error {
	var err error
	var fds []os.FileInfo
	var srcinfo os.FileInfo

	if srcinfo, err = os.Stat(src); err != nil {
		return err
	}

	if err = os.MkdirAll(dst, srcinfo.Mode()); err != nil {
		return err
	}

	if fds, err = ioutil.ReadDir(src); err != nil {
		return err
	}
	for _, fd := range fds {
		srcfp := path.Join(src, fd.Name())
		dstfp := path.Join(dst, fd.Name())

		if fd.IsDir() {
			if err = Dir(srcfp, dstfp); err != nil {
				fmt.Println(err)
			}
		} else {
			if err = File(srcfp, dstfp); err != nil {
				fmt.Println(err)
			}
		}
	}
	return nil
}