Getting unwanted characters when reading command output from SSH server using JSch

Question

I am connecting to the remote server SSH server and trying to get get the list of files in a particular path I am able to get list of files in the path but they were in unreadable format could any one help on this

String host="xxxxx.yyyy.com";
String user="user";
String password="password";
String command1="dzdo su - lucy";
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("shell");
    OutputStream ops = channel.getOutputStream();
    PrintStream ps = new PrintStream(ops, true);

    channel.connect();
    ps.println(command1);
    ps.println("ls -ltr");
    InputStream in=channel.getInputStream();
    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");

Here is the console output

drwxrws---. 2 gleaiid gleai 4096 Jan 21  2016 [0m[01;34mold[0m
-rwxrws---. 1 jhon gleai  100 Jul 20  2017 [30;43mNVISAP_814_Test.txt[0m
-rwxrws---. 1 jhon  gleai  134 Jul 20  2017 [30;43mUS_NISC14_4164556_Test.txt[0m
-rwxrws---. 1 jhon  gleai    0 Jul 20  2017 [30;43mNVISAP_R00814_Test.trg[0m

Martin Prikryl · Accepted Answer · 2025-03-18 10:01:51Z

These are ANSI escape codes that are normally interpreted by a terminal client to pretty [color] print the output.

If the server is correctly configured, you get these only, when you use an interactive terminal. In other words, if you requested a pseudo terminal for the session (what you should not, if you are automating the session).

The JSch automatically requests the pseudo terminal, if you used a "shell" channel, as that is supposed to be used for implementing an interactive terminal.

If you automate an execution of remote commands, you better use an "exec" channel, as shown in JSch Exec.java example.
Alternatively, you can prevent JSch from requesting the pseudo terminal by calling setPty. But I do not recommend using "shell" channel. Though if you need to, for whatever reason, you should call setPty(false) in any case, as that will prevent many other similar troubles. I actually already recommended that to you in your previous question.

Note to others: While I see why OP uses ls command, in general, one should use use SFTP API to retrieve a directory listing, instead of executing ls and parsing its output. Parsing ls output is a pretty unreliable approach.

1 Comment

Martin Prikryl Over a year ago

That about the same as setPty(false) and less straightforward.

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