使用jcraft官方演示进行ssh连接，但得到'zsh：1：命令未找到：roscore exit-status：127'

Question

我需要用我的android手机在我的机器人的计算机上调用'roslaunch'命令。（计算机上没有键盘或屏幕。）

我的解决方案是使用ssh在shell上发出命令。因此，我找到了jcraft。当我运行官方网站（http://www.jcraft.com/jsch/examples/Exec.java.html）上的程序时：

/* -*-mode:java; c-basic-offset:2; indent-tabs-mode:nil -*- */
/**
 * This program will demonstrate remote exec.
 *   $ CLASSPATH=.:../build javac Exec.java 
 *   $ CLASSPATH=.:../build java Exec
 * You will be asked username, hostname, displayname, passwd and command.
 * If everything works fine, given command will be invoked 
 * on the remote side and outputs will be printed out.
 *
 */
import com.jcraft.jsch.*;
import java.awt.*;
import javax.swing.*;
import java.io.*;

public class Exec{
    public static void main(String[] arg){
        try{
            JSch jsch=new JSch();

            String host=null;
            if(arg.length>0){
                host=arg[0];
            }
            else{
                host=JOptionPane.showInputDialog("Enter username@hostname",
                        System.getProperty("user.name")+
                                "@localhost");
            }
            String user=host.substring(0, host.indexOf('@'));
            host=host.substring(host.indexOf('@')+1);

            Session session=jsch.getSession(user, host, 22);

      /*
      String xhost="127.0.0.1";
      int xport=0;
      String display=JOptionPane.showInputDialog("Enter display name", 
                                                 xhost+":"+xport);
      xhost=display.substring(0, display.indexOf(':'));
      xport=Integer.parseInt(display.substring(display.indexOf(':')+1));
      session.setX11Host(xhost);
      session.setX11Port(xport+6000);
      */

            // username and password will be given via UserInfo interface.
            UserInfo ui=new MyUserInfo();
            session.setUserInfo(ui);
            session.connect();

            String command=JOptionPane.showInputDialog("Enter command",
                    "set|grep SSH");

            Channel channel=session.openChannel("exec");
            ((ChannelExec)channel).setCommand(command);

            // X Forwarding
            // channel.setXForwarding(true);

            //channel.setInputStream(System.in);
            channel.setInputStream(null);

            //channel.setOutputStream(System.out);

            //FileOutputStream fos=new FileOutputStream("/tmp/stderr");
            //((ChannelExec)channel).setErrStream(fos);
            ((ChannelExec)channel).setErrStream(System.err);

            InputStream in=channel.getInputStream();

            channel.connect();

            byte[] tmp=new byte[1024];
            while(true){
                while(in.available()>0){
                    int i=in.read(tmp, 0, 1024);
                    if(i<0)break;
                    System.out.print(new String(tmp, 0, i));
                }
                if(channel.isClosed()){
                    if(in.available()>0) continue;
                    System.out.println("exit-status: "+channel.getExitStatus());
                    break;
                }
                try{Thread.sleep(1000);}catch(Exception ee){}
            }
            channel.disconnect();
            session.disconnect();
        }
        catch(Exception e){
            System.out.println(e);
        }
    }

    public static class MyUserInfo implements UserInfo, UIKeyboardInteractive{
        public String getPassword(){ return passwd; }
        public boolean promptYesNo(String str){
            Object[] options={ "yes", "no" };
            int foo=JOptionPane.showOptionDialog(null,
                    str,
                    "Warning",
                    JOptionPane.DEFAULT_OPTION,
                    JOptionPane.WARNING_MESSAGE,
                    null, options, options[0]);
            return foo==0;
        }

        String passwd;
        JTextField passwordField=(JTextField)new JPasswordField(20);

        public String getPassphrase(){ return null; }
        public boolean promptPassphrase(String message){ return true; }
        public boolean promptPassword(String message){
            Object[] ob={passwordField};
            int result=
                    JOptionPane.showConfirmDialog(null, ob, message,
                            JOptionPane.OK_CANCEL_OPTION);
            if(result==JOptionPane.OK_OPTION){
                passwd=passwordField.getText();
                return true;
            }
            else{
                return false;
            }
        }
        public void showMessage(String message){
            JOptionPane.showMessageDialog(null, message);
        }
        final GridBagConstraints gbc =
                new GridBagConstraints(0,0,1,1,1,1,
                        GridBagConstraints.NORTHWEST,
                        GridBagConstraints.NONE,
                        new Insets(0,0,0,0),0,0);
        private Container panel;
        public String[] promptKeyboardInteractive(String destination,
                                                  String name,
                                                  String instruction,
                                                  String[] prompt,
                                                  boolean[] echo){
            panel = new JPanel();
            panel.setLayout(new GridBagLayout());

            gbc.weightx = 1.0;
            gbc.gridwidth = GridBagConstraints.REMAINDER;
            gbc.gridx = 0;
            panel.add(new JLabel(instruction), gbc);
            gbc.gridy++;

            gbc.gridwidth = GridBagConstraints.RELATIVE;

            JTextField[] texts=new JTextField[prompt.length];
            for(int i=0; i<prompt.length; i++){
                gbc.fill = GridBagConstraints.NONE;
                gbc.gridx = 0;
                gbc.weightx = 1;
                panel.add(new JLabel(prompt[i]),gbc);

                gbc.gridx = 1;
                gbc.fill = GridBagConstraints.HORIZONTAL;
                gbc.weighty = 1;
                if(echo[i]){
                    texts[i]=new JTextField(20);
                }
                else{
                    texts[i]=new JPasswordField(20);
                }
                panel.add(texts[i], gbc);
                gbc.gridy++;
            }

            if(JOptionPane.showConfirmDialog(null, panel,
                    destination+": "+name,
                    JOptionPane.OK_CANCEL_OPTION,
                    JOptionPane.QUESTION_MESSAGE)
                    ==JOptionPane.OK_OPTION){
                String[] response=new String[prompt.length];
                for(int i=0; i<prompt.length; i++){
                    response[i]=texts[i].getText();
                }
                return response;
            }
            else{
                return null;  // cancel
            }
        }
    }
}

我成功运行像ls这样的命令并获得反馈。但是，运行roscore时遇到问题：

zsh:1: command not found: roscore
exit-status: 127

此外，当我运行像'jupyter notebook'这样的命令时，我也得到：

zsh:1: command not found: jupyter
exit-status: 127

但实际上我可以在电脑上运行roscore和jupyter笔记本。我希望知道如何更改程序来解决问题？或者我如何以另一种方式在计算机上运行roslaunch？