calculate directory size in GO

dirsize.go

package main

import (
   "fmt"
   "os"
   "path/filepath"
   "log"
   "code.cloudfoundry.org/bytefmt"
)

func DirSize(path string) (uint64, error) {
    var size uint64
    err := filepath.Walk(path, func(_ string, info os.FileInfo, err error) error {
        if !info.IsDir() {
            size += uint64(info.Size())
        }
        return err
    })
    return size, err
}

func main() {
    if len(os.Args) != 2 {
       fmt.Printf("usage: %s [directory path]\n", os.Args[0])
       os.Exit(1)
    }
        m, err := DirSize(os.Args[1])
	if err != nil {
	  log.Fatal(err)
	}
	fmt.Printf(bytefmt.ByteSize(m))
}