如何在golang程序中运行二进制文件并通过发送一些输入并等待输出来保持与之交互？

Question

How can I run a binary file in my golang program and keep interacting with it by sending some input and waiting for the output? In what I did, I run it only once. And I want to keep this binary file running and interact with it, I don't want to run it multiple times.

package main

import (
    "os/exec"
    "bytes"
    "fmt"
)

func main() {
    command := exec.Command("./program")
    var output bytes.Buffer
    command.Stdout = &output
    command.Run()
    result := output.String()
    IV := result[:4]
    cipher := result[5:]
    cipher = cipher[:len(cipher)-1]
    fmt.Printf("%v", result)
    fmt.Printf("%v", IV)
    fmt.Printf("%v", cipher)
}

Answer 1

I believe the right way to accomplish this is using the StdinPipe and StdoutPipe methods of exec.Cmd.

See examples in https://golang.org/pkg/os/exec/#Cmd.StdinPipe, etc.

---

Here's an example that invokes the bc command (built-in calculator that takes calculations from stdin and emits results to stdout) and interacts with it a bit:

package main

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

func main() {
    cmd := exec.Command("bc", "-q")

    stdin, err := cmd.StdinPipe()
    if err != nil {
        log.Fatal(err)
    }

    stdout, err := cmd.StdoutPipe()
    if err != nil {
        log.Fatal(err)
    }

    if err := cmd.Start(); err != nil {
        log.Fatal(err)
    }

    stdin.Write([]byte("2 + 2
"))

    r := bufio.NewReader(stdout)
    b, err := r.ReadBytes('
')
    if err != nil {
        log.Fatal(err)
    }
    fmt.Println("Read:", string(b))
}

In a real program you may want to run this thing in a goroutine so it doesn't block the rest of the application, happens in the background, etc.