package main

import (
	"bytes"
	"fmt"
	"io"
	"os"
)

func tmpPrint() {
	fmt.Println("output")
}

func main() {
	old := os.Stdout // keep backup of the real stdout
	r, w, _ := os.Pipe()
	os.Stdout = w

	tmpPrint()

	outC := make(chan string)
	// copy the output in a separate goroutine so printing can't block indefinitely
	go func() {
		var buf bytes.Buffer
		io.Copy(&buf, r)
		outC <- buf.String()
	}()

	// back to normal state
	w.Close()
	os.Stdout = old // restoring the real stdout
	out := <-outC

	// reading our temp stdout
	fmt.Println("previous output:")
	fmt.Print(out)
}