update

fetch/main.go

@@ -0,0 +1,39 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"os"
+	"time"
+)
+
+func main() {
+	start := time.Now()
+	ch := make(chan string)
+	for _, url := range os.Args[1:] {
+		go fetch(url, ch)
+	}
+	for range os.Args[1:] {
+		fmt.Println(<-ch)
+	}
+	fmt.Printf("%.2fs elapsed\n", time.Since(start).Seconds())
+}
+
+func fetch(url string, ch chan<- string) {
+	start := time.Now()
+	resp, err := http.Get(url)
+	if err != nil {
+		ch <- fmt.Sprint(err)
+		return
+	}
+	defer resp.Body.Close()
+	nbytes, err := io.Copy(ioutil.Discard, resp.Body)
+	if err != nil {
+		ch <- fmt.Sprintf("while reading %s: %v", url, err)
+		return
+	}
+	secs := time.Since(start).Seconds()
+	ch <- fmt.Sprintf("%.2fs %7d %s", secs, nbytes, url)
+}

flag/README.md

@@ -0,0 +1,7 @@
+```bash
+go run .\main.go -h
+go run .\main.go --help
+go run .\main.go a bc zfx
+go run .\main.go -s / a bc zfx
+go run .\main.go -n a bc zfx
+```

flag/main.go

@@ -0,0 +1,18 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"strings"
+)
+
+var n = flag.Bool("n", false, "omit trailling newline")
+var sep = flag.String("s", " ", "separator")
+
+func main() {
+	flag.Parse()
+	fmt.Print(strings.Join(flag.Args(), *sep))
+	if !*n {
+		fmt.Println()
+	}
+}