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Thread: Error connecting to Unix and running script from Java code

  1. #1
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    Default Error connecting to Unix and running script from Java code

    I get the following error when trying to run code. Please help.

    java.lang.NullPointerException
    at conntecttoDB8.SSHCommandExecutor.main(SSHCommandEx ecutor.java:26)


    package conntecttoDB8;
    import java.io.InputStream;
     
    import com.jcraft.jsch.Channel;
    import com.jcraft.jsch.JSch;
    import com.jcraft.jsch.Session;
     
     
    public class SSHCommandExecutor {
     
        /**
         * @param args
         */
        public static void main(String[] args) {
        	//String host="xxxxxxxxxxxxxx";
        	String host="xxxxxxxxxxxxxxx";
    		String user="xxxxxxxxxxxxx";
    		String password="xxxxxxxxxxxx";
    		String command1="ls -ltr";
            try{
     
                java.util.Properties config = new java.util.Properties(); 
                config.put("StrictHostKeyChecking", "no");
                JSch jsch = new JSch();
                Session session=jsch.getSession(user, host, 22);
                session.setPassword(password);
                session.setConfig(config);
                session.connect();
                System.out.println("Connected"); 
                Channel channel=session.openChannel("exec");
                channel.setCommand(command1);
                channel.setInputStream(null);
                channel.setInputStream(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()){
                    System.out.println("exit-status: "+channel.getExitStatus());
                    break;
                  }
                  try{Thread.sleep(1000);}catch(Exception ee){}
                }
                channel.disconnect();
                session.disconnect();
                System.out.println("DONE");
            }catch(Exception e){
                e.printStackTrace();
            } finally {
    		}
     
        }
     
    }
     
    package com.jcraft.jsch;
     
    import java.util.Properties;
     
    public class Session {
     
    	public void connect() {
     
     
    	}
     
    	public Channel openChannel(String string) {
    		return null;
     
     
    	}
     
    	public void setConfig(Properties config) {
     
     
    	}
     
    	public void setPassword(String password) {
     
    	}
     
    	public void disconnect() {
     
    	}
     
    }
     
    package com.jcraft.jsch;
     
    import java.io.PrintStream;
     
    public class ChannelExec {
     
    	public void setCommand(String command1) {
     
     
    	}
     
    	public void setErrStream(PrintStream err) {
     
     
    	}
     
    }
     
    package com.jcraft.jsch;
     
    import java.io.InputStream;
     
    public class Channel {
     
    	public void setInputStream(Object object) {
     
     
    	}
     
    	public InputStream getInputStream() {
     
    		return null;
    	}
     
    	public void connect() {
     
     
    	}
     
    	public boolean isClosed() {
     
    		return false;
    	}
     
    	public String getExitStatus() {
     
    		return null;
    	}
     
    	public void disconnect() {
     
     
    	}
     
    	public void setCommand(String command1) {
     
     
    	}
     
    }


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: Error connecting to Unix and running script from Java code

    java.lang.NullPointerException
    at conntecttoDB8.SSHCommandExecutor.main(SSHCommandEx ecutor.java:26)
    There was a null value at line 26. Look at line 26 to find what was null. Then backtrack in the code to see why it was null.
    If you don't understand my answer, don't ignore it, ask a question.

  3. #3
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    Default Re: Error connecting to Unix and running script from Java code

    Thanks,

    I did ask suggested and all variables prior have values.

  4. #4
    Super Moderator Norm's Avatar
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    Default Re: Error connecting to Unix and running script from Java code

    What statement is on line 26?

    That error usually means there is a null value. How did you check the values on that line?
    If you don't understand my answer, don't ignore it, ask a question.

  5. #5
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    Default Re: Error connecting to Unix and running script from Java code

    line d6 session.setPassword(password);

    It is the session value that is null

  6. #6
    Super Moderator Norm's Avatar
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    Default Re: Error connecting to Unix and running script from Java code

    Its value is returned by the getSession() method. You need to read the API doc for the method to see why it returns a null value.
    I don't know anything about the packages, classes and methods the code is using.
    If you don't understand my answer, don't ignore it, ask a question.

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