如何在golang中将标准输出同时保存到字符串的同时打印到标准输出？

Question

What I want to do is like:

cmd := exec.Command(someCommand)
cmd.Stdout = os.Stdout
cmd.Run()
save(os.Stdout)

Because this command takes a long time executing, I want to print results on the screen immediately. So I do not want to use result := cmd.Output() fmt.Print(result) to save the output and then print

Answer 1

Usa a MultiWriter:

cmd := exec.Command(someCommand)
var buf bytes.Buffer
cmd.Stdout = io.MultiWriter(os.Stdout, &buf)
cmd.Run()
save(buf.Bytes())  // Bytes() returns a []byte containing the stdout from the commmand.