Commons Net example source code file (rshell.java)

This example Commons Net source code file (rshell.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Commons Net tags/keywords

io, ioexception, ioexception, rcommandclient, rcommandclient, string, string, usage, usage

The Commons Net rshell.java source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package examples.unix;

import java.io.IOException;
import org.apache.commons.net.bsd.RCommandClient;

import examples.util.IOUtil;

/***
 * This is an example program demonstrating how to use the RCommandClient
 * class. This program connects to an rshell daemon and requests that the
 * given command be executed on the server.  It then reads input from stdin
 * (this will be line buffered on most systems, so don't expect character
 * at a time interactivity), passing it to the remote process and writes
 * the process stdout and stderr to local stdout.
 * <p>
 * On Unix systems you will not be able to use the rshell capability
 * unless the process runs as root since only root can bind port addresses
 * lower than 1024.
 * <p>
 * Example: java rshell myhost localusername remoteusername "ps -aux"
 * <p>
 * Usage: rshell <hostname>   
 * <p>
 ***/

// This class requires the IOUtil support class!
public final class rshell
{

    public static final void main(String[] args)
    {
        String server, localuser, remoteuser, command;
        RCommandClient client;

        if (args.length != 4)
        {
            System.err.println(
                "Usage: rshell <hostname>   ");
            System.exit(1);
            return ; // so compiler can do proper flow control analysis
        }

        client = new RCommandClient();

        server = args[0];
        localuser = args[1];
        remoteuser = args[2];
        command = args[3];

        try
        {
            client.connect(server);
        }
        catch (IOException e)
        {
            System.err.println("Could not connect to server.");
            e.printStackTrace();
            System.exit(1);
        }

        try
        {
            client.rcommand(localuser, remoteuser, command);
        }
        catch (IOException e)
        {
            try
            {
                client.disconnect();
            }
            catch (IOException f)
            {}
            e.printStackTrace();
            System.err.println("Could not execute command.");
            System.exit(1);
        }


        IOUtil.readWrite(client.getInputStream(), client.getOutputStream(),
                         System.in, System.out);

        try
        {
            client.disconnect();
        }
        catch (IOException e)
        {
            e.printStackTrace();
            System.exit(1);
        }

        System.exit(0);
    }

}