package main import ( "fmt" "encoding/json" "os" "math/rand" ) const lBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ" type OutputSize struct { Size int `json:"size"` } func RandStringBytes(n int) string { b := make([]byte, n) for i := range b { b[i] = lBytes[rand.Intn(len(lBytes))] } return string(b) } func main() { out := &OutputSize{Size: 64 * 1024} json.NewDecoder(os.Stdin).Decode(out) fmt.Fprintln(os.Stderr, RandStringBytes(out.Size)) }