Using stdout and stdin from other programs in Golang

Golang program stdin stdout interaction.md

Go program interaction

Example of how to use stdout and stdin from other programs in golang

Requires go

Run

go run parentprocess.go

parentprocess.go

package main

import (
	"bufio"
	"io"
	"log"
	"os"
	"os/exec"
)

func main() {

	cmd := exec.Command("./subprocess.sh")
	cmd.Stderr = os.Stderr
	stdin, err := cmd.StdinPipe()
	if nil != err {
		log.Fatalf("Error obtaining stdin: %s", err.Error())
	}
	stdout, err := cmd.StdoutPipe()
	if nil != err {
		log.Fatalf("Error obtaining stdout: %s", err.Error())
	}
	reader := bufio.NewReader(stdout)
	go func(reader io.Reader) {
		scanner := bufio.NewScanner(reader)
		for scanner.Scan() {
			log.Printf("Reading from subprocess: %s", scanner.Text())
			stdin.Write([]byte("some sample text\n"))
		}
	}(reader)
	if err := cmd.Start(); nil != err {
		log.Fatalf("Error starting program: %s, %s", cmd.Path, err.Error())
	}
	cmd.Wait()

}

subprocess.sh

#!/bin/bash

echo "Enter some text:"
read -r input
echo "you typed: $input"

Thanks for posting this. I have a question though. If I understand this correctly it is actually running everything at once. Is there a way to do a similar thing where it is more interactive? I'd like to wait for data to be presented by the program and then process it as it comes in.

Yes you can use the aync example in this link. Just create a goroutine around the stdin, stdout, and take relevant action. Let me know if you need help...