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How to pass a file from a remote host to another remote host in java?

I have been working on an application that uses JSCH to scp and transfer a file to another directory in the same server. However, I want to be able to transfer a file from one remote host to another remote host in an automated way. Below is the code I use to make the call. I have tried using other scp commands such as: scp [options] username1#source_host:directory1/filename1 username2#destination_host:directory2/filename2. It works when testing it on the server itself but when I try to incorporate it into the code below, it passes back an error.
CODE:
public static void main(String[] args){
String array [] = {"robert.txt","ops1axv#gaalpltclu00029.linux.us.ams1907.com:/tmp"};
if(array.length!=2){
System.err.println("usage: java ScpTo file1 user#remotehost:file2");
System.exit(-1);
}
FileInputStream fis=null;
try{
String lfile=array[0];
String user=array[1].substring(0, array[1].indexOf('#'));
array[1]=array[1].substring(array[1].indexOf('#')+1);
String host=array[1].substring(0, array[1].indexOf(':'));
String rfile=array[1].substring(array[1].indexOf(':')+1);
System.out.println("RFile: " + rfile );
System.out.println("Lfile: " + lfile);
JSch jsch=new JSch();
Session session=jsch.getSession(user, host, 22);
// username and password will be given via UserInfo interface.
UserInfo ui=new MyUserInfo();
session.setUserInfo(ui);
session.connect();
boolean ptimestamp = true;
// exec 'scp -t rfile' remotely
String command="scp " + (ptimestamp ? "-p" :"") +" -t "+rfile;
Channel channel=session.openChannel("exec");
((ChannelExec)channel).setCommand(command);
// get I/O streams for remote scp
OutputStream out=channel.getOutputStream();
InputStream in=channel.getInputStream();
channel.connect();
if(checkAck(in)!=0){
System.exit(0);
}
File _lfile = new File(lfile);
if(ptimestamp){
command="T"+(_lfile.lastModified()/1000)+" 0";
// The access time should be sent here,
// but it is not accessible with JavaAPI ;-<
command+=(" "+(_lfile.lastModified()/1000)+" 0\n");
out.write(command.getBytes()); out.flush();
if(checkAck(in)!=0){
System.exit(0);
}
}
// send "C0644 filesize filename", where filename should not include '/'
long filesize=_lfile.length();
command="C0644 "+filesize+" ";
if(lfile.lastIndexOf('/')>0){
command+=lfile.substring(lfile.lastIndexOf('/')+1);
}
else{
command+=lfile;
}
command+="\n";
out.write(command.getBytes()); out.flush();
if(checkAck(in)!=0){
System.exit(0);
}
// send a content of lfile
fis=new FileInputStream(lfile);
byte[] buf=new byte[1024];
while(true){
int len=fis.read(buf, 0, buf.length);
if(len<=0) break;
out.write(buf, 0, len); //out.flush();
}
fis.close();
fis=null;
// send '\0'
buf[0]=0; out.write(buf, 0, 1); out.flush();
if(checkAck(in)!=0){
System.exit(0);
}
out.close();
channel.disconnect();
session.disconnect();
System.exit(0);
}
catch(Exception e){
System.out.println(e);
try{if(fis!=null)fis.close();}catch(Exception ee){}
}
}

Unix commands become, cd and ls -la to be run via java code

I am supposed to connect to a Unix server, then go to the specific folder(which has got access restrictions) and fetch the file details from there. For the same , the code that I have written is
try{
Session session = new JSch().getSession("username", "host");
session.setPassword("password");
java.util.Properties config = new java.util.Properties();
config.put("StrictHostKeyChecking", "no");
session.setConfig(config);
session.connect();
Channel channel=session.openChannel("exec");
((ChannelExec)channel).setCommand("cd a/b/node01/c.ear && ls -la");
channel.connect();
channel.run();
InputStream in = channel.getInputStream();
System.out.println(channel.isConnected());
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;
}
}
channel.disconnect();
session.disconnect();
}
catch(Exception exception){
System.out.println("Got exception "+exception);
}
I am not getting the list of files that are present in the location supplied.
The output that I am getting is
true
exit-status: 1
How do I get the desired output?

Do not use shell commands to retrieve file information. Use SFTP!
Channel channel = session.openChannel("sftp");
channel.connect();
ChannelSftp c = (ChannelSftp)channel;
java.util.Vector vv = c.ls("/a/b/node01/c.ear");
for (int i = 0; i < vv.size(); i++)
{
System.out.println(vv.elementAt(i).toString());
}
See http://www.jcraft.com/jsch/examples/Sftp.java.html
Regarding your code for "exec" channel:
First, the code has a recurring flaw described in:
Randomly getting empty output while executing shell command via JSch.
Though to actually debug your problem, you have to read both stdout and stderr to collect any errors (which you are obviously getting).
For that see Log stdout and stderr from ssh command in the same order it was created.

A possible problem here is the usage of in.available(). It returns the number of bytes that can be read without blocking.
The correct way to read a stream until eof is:
byte[] buf = new byte[1024];
int len;
while ((len=in.read(buf)) >= 0) {
// do something with buf[0 .. len]
}

Run docker command with JSch [duplicate]

Short Version: Is it possible to log the stdout and stderr on the local side of a command executed remotely via ssh in the same order as it was output on the remote host? If so, how?
Long Version:
I am attempting to log the standard and error output from a remotely exec'd SSH command (using Jsch) in the same order as it was output by the remote command. In other words, if the remote command writes "a" to stdout, then "b" to stderr, then "c" to stdout, I want the log on the client (local) side to read:
a
b
c
Below is what I have so far. It comes relatively close to what I want, but I think it will be apparent that it does not guarantee the correct output order on the client side.
public int exec(String strCommand) throws ExceptionUnableToExecCommand {
JSch jsch = new JSch();
Session session = null;
ChannelExec channel = null;
try {
session = jsch.getSession(user, host, 22);
UserInfo ui = new cyclOps.jsch.UserInfo(password);
session.setUserInfo(ui);
session.connect();
channel = (ChannelExec) session.openChannel("exec");
channel.setCommand(strCommand);
channel.setInputStream(null);
InputStream in = channel.getInputStream();
InputStream err = channel.getErrStream();
channel.connect();
/* getOutput() defined below. */
return this.getOutput(channel, in, err);
} catch (JSchException | IOException e) {
throw new ExceptionUnableToExecCommand("Unable to execute " + strCommand + " " + this.toString(), e);
} finally {
if (channel != null) channel.disconnect();
if (session != null) session.disconnect();
}
}
private int getOutput(ChannelExec channel, InputStream in, InputStream err) throws IOException {
byte[] tmp = new byte[1024];
while(true){
while(in.available() > 0){
int i=in.read(tmp, 0, 1024);
if(i<0)break;
this.sshLogger.logOutputFromSSH(new String(tmp, 0, i));
}
while(err.available() > 0){
int i=err.read(tmp, 0, 1024);
if(i<0)break;
this.sshLogger.logOutputFromSSH(new String(tmp, 0, i));
}
if(channel.isClosed()){
return channel.getExitStatus();
}
try{Thread.sleep(1000);}catch(Exception ee){}
}
}
I think I should point out that this is a modified version of Exec.java from the Jsch web site examples.

How about the following chunk of code?
channel.setCommand(command);
PipedOutputStream pos=new PipedOutputStream();
PipedInputStream pis=new PipedInputStream(pos);
channel.setOutputStream(pos);
channel.setExtOutputStream(pos);
InputStream in=pis;
channel.connect();

You are working with separate streams, so no, there is no way you can possibly guarantee to get the exact same output.
that said, your code has a number of potential problems, among them:
InputStream.available is a generally useless method and should be avoided
you are reading bytes and converting arbitrary byte arrays to chars/Strings, which could result in broken output (if you are getting multi-byte chars you could end up splitting them).
reading 2 different blocking streams with a single thread can result in deadlock

JSch - command not being sent to shell?

I'm working on a project to restart something within a screen on a remote server using JSch... however I'm running into an issue. It will send the first 2 commands 100% of the time, but the 3rd command will only be sent some of the time. Any help would be appreciated.
public static void stopServer(String name, String ip, String passwd)
{
try {
Session session = Main.jsch.getSession("user",ip,22);
session.setConfig("StrictHostKeyChecking", "no");
session.setPassword(passwd);
session.connect();
Channel channel = session.openChannel("shell");
channel.connect();
ChannelShell cs = (ChannelShell) channel;
cs.setPty(true);
DataInputStream dataIn = new DataInputStream(channel.getInputStream());
PrintStream dataOut = new PrintStream(channel.getOutputStream());
dataOut.println("screen -x "+name);
dataOut.flush();
dataOut.println("stop");
dataOut.flush();
String line = dataIn.readLine();
System.out.println(line);
while(true) {
line = dataIn.readLine();
System.out.println(line);
if(line.contains("\"quit\""))
{
break;
}
}
TimeUnit.SECONDS.sleep(1);
dataOut.println("quit");
dataOut.flush();
System.out.println("Shutdown");
dataIn.close();
dataOut.close();
channel.disconnect();
session.disconnect();
}catch(Exception e)
{
e.printStackTrace();
}
}
This sends the screen -x 'name' and the stop 100% of the time from what I've seen, but the 'quit' command only actually gets sent/understood by the console a fraction of the time. Any help would be appreciated!!

I managed to fix this in a way that doesn't use the shell channel, but it is reliable enough that it works:
//Start EXEC
ChannelExec ce = (ChannelExec) session.openChannel("exec");
ce.setCommand("screen -S " + name + " -X stuff 'quit\n'");
ce.setInputStream(null);
ce.setErrStream(System.err);
InputStream in=ce.getInputStream();
ce.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(ce.isClosed()){
if(in.available()>0) continue;
//System.out.println("exit-status: "+ce.getExitStatus());
break;
}
try{Thread.sleep(1000);}catch(Exception ee){}
}
ce.disconnect();
//STOP EXEC
As much as this doesn't work along the original vein of the problem, it fixed it for me.

If an exception gets thrown sometime before the "quit" command gets sent, then the quit command will never get sent.
If the while loop never breaks, then that will prevent the "quit"
command from being sent too.

Jsch : Command Output unavailable

I am trying to use jsch to connect to a remote switch and run some command and extract the output.
I am able to connect to the switch using , however the command output is not available in the inputstream. Maybe i am not doing it the right way. Here's the code
session = jsch.getSession("user", "10.0.0.0", 22);
session.setPassword("somepwd");
session.setConfig("StrictHostKeyChecking", "no");
session.connect();
System.out.println("connected to remote host");
Channel channel = session.openChannel("shell");
OutputStream ops = channel.getOutputStream();
PrintStream ps = new PrintStream(ops);
channel.connect();
ps.println("show version");
ps.flush();
ps.close();
InputStream in=channel.getInputStream();
byte[] bt=new byte[1024];
while(in.available()>0)
{
int i=in.read(bt, 0, 1024);
if(i<0)
break;
String str=new String(bt, 0, i);
//displays the output of the command executed.
System.out.print(str);
}
channel.disconnect();
session.disconnect();
When i debug the inputStream.isAvailable() always returns zero suggesting that there is no output from the command.
TIA!

Please try the code below - tested and working
Channel channel = session.openChannel("shell");
OutputStream ops = channel.getOutputStream();
PrintStream ps = new PrintStream(ops);
channel.connect();
ps.println("pwd");
ps.println("exit");
ps.flush();
ps.close();
InputStream in = channel.getInputStream();
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
System.out.println("Opening...");
String jarOutput;
while ((jarOutput = reader.readLine()) != null)
System.out.println(jarOutput);
reader.close();
channel.disconnect();
Output -
Opening...
user#host:~> pwd
/home/user
user#host:~>
user#host:~> exit
logout