Golang-过滤活动SSH会话的标准输出

Question

I'm writing an SSH client in Go that connects to a switch and runs a list of configuration commands. So far, I am able to successfully connect to a switch, run the desired commands, and print the output of the session. The problem comes when the switch is expecting a , space, or "q" to be entered when a command's output is too long. For example:

switch#show int status

Port      Name               Status       Vlan       Duplex  Speed Type
Gi1/0/1                      notconnect   100          auto   auto 10/100/1000BaseTX
Gi1/0/2                      connected    915        a-full  a-100 10/100/1000BaseTX
Gi1/0/3                      notconnect   100          auto   auto 10/100/1000BaseTX
Gi1/0/4                      notconnect   100          auto   auto 10/100/1000BaseTX
Gi1/0/5                      notconnect   230          auto   auto 10/100/1000BaseTX
...
Po1       sw-sww-100-sww-0-0 connected    trunk      a-full    10G
 --More-- # Program hangs here; expecting a new line, space, or 'q'

The --More-- prompt is not actually printed to the screen, so simply checking if the current line of Stdout contains --More-- and sending a , space, or "q" does not work.

In addition to fixing this problem, I'd like to filter Stdout of the session so that the only thing printed is the output of each command. In other words, I don't want the switch's prompt to be printed to the terminal.

To sum up:

1. How to capture and print only the output of each command?
2. How to send a new line, space, or letter "q" when prompted?

Any help is appreciated. Here is my code:

package main

import (
    "bufio"
    "fmt"
    "golang.org/x/crypto/ssh"
    "io"
    "log"
    "os"
    "time"
)

type Device struct {
    Config  *ssh.ClientConfig
    Client  *ssh.Client
    Session *ssh.Session
    Stdin   io.WriteCloser
    Stdout  io.Reader
    Stderr  io.Reader
}

func (d *Device) Connect() error {
    client, err := ssh.Dial("tcp", os.Args[1]+":22", d.Config)
    if err != nil {
        return err
    }
    session, err := client.NewSession()
    if err != nil {
        return err
    }
    sshIn, err := session.StdinPipe()
    if err != nil {
        return err
    }
    sshOut, err := session.StdoutPipe()
    if err != nil {
        return err
    }
    sshErr, err := session.StderrPipe()
    if err != nil {
        return err
    }
    d.Client = client
    d.Session = session
    d.Stdin = sshIn
    d.Stdout = sshOut
    d.Stderr = sshErr
    return nil
}

func (d *Device) SendCommand(cmd string) error {
    if _, err := io.WriteString(d.Stdin, cmd+"
"); err != nil {
        return err
    }
    return nil
}

func (d *Device) SendConfigSet(cmds []string) error {
    for _, cmd := range cmds {
        if _, err := io.WriteString(d.Stdin, cmd+"
"); err != nil {
            return err
        }
        time.Sleep(time.Second)
    }
    return nil
}

func (d *Device) PrintOutput() {
    r := bufio.NewReader(d.Stdout)
    for {
        text, err := r.ReadString('
')
        fmt.Printf("%s", text)
        if err == io.EOF {
            break
        }
    }
}

func (d *Device) PrintErr() {
    r := bufio.NewReader(d.Stderr)
    for {
        text, err := r.ReadString('
')
        fmt.Printf("%s", text)
        if err == io.EOF {
            break
        }
    }
}

func main() {
    sshConf := ssh.Config{}
    sshConf.Ciphers = append(sshConf.Ciphers, "aes128-cbc", "3des-cbc", "blowfish-cbc", "arcfour")
    config := &ssh.ClientConfig{
        Config: sshConf,
        User:   "mwalto7",
        Auth: []ssh.AuthMethod{
            ssh.Password("Lion$Tiger$Bear$"),
        },
        HostKeyCallback: ssh.InsecureIgnoreHostKey(),
        Timeout:         time.Second * 5,
    }

    sw := &Device{Config: config}

    fmt.Println("Connecting to ", os.Args[1])
    if err := sw.Connect(); err != nil {
        log.Fatal(err)
    }
    defer sw.Client.Close()
    defer sw.Session.Close()
    defer sw.Stdin.Close()

    if err := sw.Session.Shell(); err != nil {
        log.Fatal(err)
    }

    commands := []string{"show int status", "exit"}
    if err := sw.SendConfigSet(commands); err != nil {
        log.Fatal(err)
    }

    sw.Session.Wait()

    sw.PrintOutput()
    sw.PrintErr()
}

Answer 1

I fixed this problem by sending the command terminal length 0 just after connecting to the switch, before sending the rest of the commands. This disabled the —More— prompt by setting the switch’s terminal height to 0, allowing the whole output of a command to be displayed.