package main import ( "io" "io/ioutil" "os" ) func main() { if len(os.Args) == 1 { if _, err := io.Copy(os.Stdout, os.Stdin); err != nil { panic(err) } } else { for _, arg := range os.Args[1:] { data, err := ioutil.ReadFile(arg) if err != nil { panic(err) } os.Stdout.Write(data) } } }