gistfile1.go

package main

import (
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"strings"
	"sync"
)

var saveDir string = "/tmp"

func main() {
	var wg sync.WaitGroup
	for _, url := range os.Args[1:] {
		wg.Add(1)
		saveFile := strings.Split(url, "/")
		fmt.Println("Download ", url)
		go func() {
			defer wg.Done()
			err := download(url, saveDir+"/"+saveFile[len(saveFile)-1])
			if err != nil {
				log.Fatal(err)
				return
			}
		}()
	}
	wg.Wait()
	fmt.Println("finish.")
}

func download(url string, filename string) error {
	file, err := os.Create(filename)
	if err != nil {
		return err
	}
	defer file.Close()

	res, err := http.Get(url)
	if err != nil {
		return err
	}
	defer res.Body.Close()

	_, err = io.Copy(file, res.Body)
	if err != nil {
		return err
	}

	return nil
}