从标准输出读取永不返回golang

Question

I am trying to read from the stdoutpipe of an SSH connection. I am able to read it when there is data in the buffer, but when I try to read later after it's empty the read hangs.

Is there a way I can check if there is data in the buffer before reading it? or is something else going on here entirely?

I made a quick example to show what I'm seeing.

package main

import (
    "fmt"
    "strconv"

    "golang.org/x/crypto/ssh"
)

func main() {
    var user = "<user>"
    var passwd = "<password>"
    var ip = "<ip>"

    sshConfig := &ssh.ClientConfig{
        User:            user,
        HostKeyCallback: ssh.InsecureIgnoreHostKey(),
        Auth: []ssh.AuthMethod{
            ssh.Password(passwd),
        },
    }

    var conn, _ = ssh.Dial("tcp", ip + ":22", sshConfig)

    var sess, _ = conn.NewSession()

    var stdin, _ = sess.StdinPipe()
    var stdout, _ = sess.StdoutPipe()
    sess.Shell()

    stdin.Write([]byte("ls
"))

    var numBytes = 1
    var readCount = 0

    for numBytes > 0 {
        fmt.Println("Read count: " + strconv.Itoa(readCount))
        var recvData = make([]byte, 1024)
        numBytes, _ = stdout.Read(recvData)
        fmt.Println(string(recvData[:numBytes]))
        readCount++
    }
}

You'll need to update the user, passwd, and ip vars, but after that you should see the program freeze after stdout is empty.