如何在字符串中获取 jsch shell 命令输出

java ssh jsch

2022-09-05 00:02:12

我正在使用JSCH -SSH库在“shell”通道中执行命令，但无法找到做2件事的方法：

1）如何查找命令是否完全在远程unix盒上执行？

2）如何在String中捕获命令输出，而不是在System.out控制台上打印？

以下是我的代码片段，它可以很好地在system.out上显示shell命令输出

注：I不想使用“exec”通道，因为它为每个命令启动一个新进程，并且不记得导出的“会话”变量。我必须使用“shell”通道。

下面是我的代码片段。任何帮助是值得赞赏的。感谢您抽出宝贵时间接受采访。

try{

  String commandToRun = "ls /tmp/*.log \n";
  if(channel.isClosed())
      channel=session.openChannel("shell");
  byte[] bytes = commandToRun.getBytes();
  ByteArrayInputStream bais=new ByteArrayInputStream(bytes);
  channel.setInputStream(bais);
  InputStream ins=channel.getInputStream();
  channel.connect();
  channel.setOutputStream(System.out);//This prints on console. Need 2 capture in String somehow?

  //in-efficient way to allow command to execute completely on remote Unix machine
  //DO NOT know a better way, to know when command is executed completely
  Thread.sleep(5000L);
}
 catch(Exception e){
  System.out.println("Exception  in executeCommand() --->"+ e.getMessage());
  e.printStackTrace();
}

答案 1

OP可能不再需要我的解决方案，但是其他任何正在寻找解决方案来涵盖这两种情况的人1）等待命令在远程计算机上完成;和2）捕获输出为字符串;你可以试试这个：

public class SshConnectionManager {

private static Session session;
private static ChannelShell channel;
private static String username = "";
private static String password = "";
private static String hostname = "";


private static Session getSession(){
    if(session == null || !session.isConnected()){
        session = connect(hostname,username,password);
    }
    return session;
}

private static Channel getChannel(){
    if(channel == null || !channel.isConnected()){
        try{
            channel = (ChannelShell)getSession().openChannel("shell");
            channel.connect();

        }catch(Exception e){
            System.out.println("Error while opening channel: "+ e);
        }
    }
    return channel;
}

private static Session connect(String hostname, String username, String password){

    JSch jSch = new JSch();

    try {

        session = jSch.getSession(username, hostname, 22);
        Properties config = new Properties(); 
        config.put("StrictHostKeyChecking", "no");
        session.setConfig(config);
        session.setPassword(password);

        System.out.println("Connecting SSH to " + hostname + " - Please wait for few seconds... ");
        session.connect();
        System.out.println("Connected!");
    }catch(Exception e){
        System.out.println("An error occurred while connecting to "+hostname+": "+e);
    }

    return session;

}

private static void executeCommands(List<String> commands){

    try{
        Channel channel=getChannel();

        System.out.println("Sending commands...");
        sendCommands(channel, commands);

        readChannelOutput(channel);
        System.out.println("Finished sending commands!");

    }catch(Exception e){
        System.out.println("An error ocurred during executeCommands: "+e);
    }
}

private static void sendCommands(Channel channel, List<String> commands){

    try{
        PrintStream out = new PrintStream(channel.getOutputStream());

        out.println("#!/bin/bash");
        for(String command : commands){
            out.println(command);
        }
        out.println("exit");

        out.flush();
    }catch(Exception e){
        System.out.println("Error while sending commands: "+ e);
    }

}

private static void readChannelOutput(Channel channel){

    byte[] buffer = new byte[1024];

    try{
        InputStream in = channel.getInputStream();
        String line = "";
        while (true){
            while (in.available() > 0) {
                int i = in.read(buffer, 0, 1024);
                if (i < 0) {
                    break;
                }
                line = new String(buffer, 0, i);
                System.out.println(line);
            }

            if(line.contains("logout")){
                break;
            }

            if (channel.isClosed()){
                break;
            }
            try {
                Thread.sleep(1000);
            } catch (Exception ee){}
        }
    }catch(Exception e){
        System.out.println("Error while reading channel output: "+ e);
    }

}

public static void close(){
    channel.disconnect();
    session.disconnect();
    System.out.println("Disconnected channel and session");
}


public static void main(String[] args){
    List<String> commands = new ArrayList<String>();
    commands.add("ls -l");

    executeCommands(commands);
    close();
}
}

如果您需要一次发送多个命令并保持通道打开状态以便以后重用，则此解决方案也很有用。

答案 2

对于2）您可以使用ByteArrayOutputStream

final ByteArrayOutputStream baos = new ByteArrayOutputStream();
channel.setOutputStream(baos);

，然后从new String(baos.toByteArray())

对于1，您是否尝试过在命令结束时使用2>&1？

String commandToRun = "ls /tmp/*.log 2>&1 \n";