Starting of external processes with Runtime.exec() properly

hi people,
you find a lot about starting external processes with the Runtime class in every forum.
-> that the stdout of the started processes has to be redirected and read
due to os buffer problems
-> that calling batches is done by starting the interpreter and the batch as parameter (cmd.exe, /bin/sh,..)
-> that the created process doesn't have an os environment
-> ...
but what if you don't know anything about the started process.
what if you only want only to start an external process. if you don't want to wait til waitfor() returns and if you don't read the streams of the created processes, the os stdout buffer will overflow immediately an the started process will be blocked.
you can read the stdout of the started process, but what if the process does print nothing to stdout, and your bufferreader.readLine() will block ?
you can do this (read buffer, waitFor()) in an separate thread, but the thread lives til the started process will finish, so maybe you got dozens of senseless thread ?
So, what is an effective and good way to start external programs/processes if you don't know about them.
so i would be grateful for an answer
regards
Alen

http://forum.java.sun.com/thread.jspa?threadID=659862&tstart=0
The first four might pass as accidents, but this one is simply idiocy, spamming and general bad manners.

Similar Messages

How to handle starting of external processes with Runtime.exec() properly

hi people,
you find a lot about starting external processes with the Runtime class in every forum.
-> that the stdout of the started processes has to be redirected and read
due to os buffer problems
-> that calling batches is done by starting the interpreter and the batch as parameter (cmd.exe, /bin/sh,..)
-> that the created process doesn't have an os environment
-> ...
but what if you don't know anything about the started process.
what if you only want only to start an external process. if you don't want to wait til waitfor() returns and if you don't read the streams of the created processes, the os stdout buffer will overflow immediately an the started process will be blocked.
you can read the stdout of the started process, but what if the process does print nothing to stdout, and your bufferreader.readLine() will block ?
you can do this (read buffer, waitFor()) in an separate thread, but the thread lives til the started process will finish, so maybe you got dozens of senseless thread ?
So, what is an effective and good way to start external programs/processes if you don't know about them.
so i would be grateful for an answer
regards
Alen

I realize that's a pat answer, but it's true. Spawing off another program without being able to predict its behavior is dangerous.
But anyway, as I understand it creating a new process is relatively expensive. The cost of creating new threads to read the process's I/O and later garbage collecting those threads when the process dies, probably isn't much of an additional burden.

Interact with extern process by Runtime.exec()

Hi,
I want interact with a extern process by Runtime.exec(), but I don't Know the way for introduce the params required for the extern process.
So, Is posible, interact with the extern process from Java?
Thanks

Exactly, I would like to know how exec can pass a PIN
number when the proccess already has been launched. Sounds like you're doing it through the process' stdin. Read that article I linked.
You'll have to call Process.getOutputStream() or whatever that method is. To you it's an OutputStream, to the process, it's input. You'll write the stuff to that stream that you'd type to the command line. If you want to get that from the user interactively, you'll do it like you would any interactive user input in any Java program--get it by reading System.in or from some GUI element, and then take that and write it to the process' stream.
If you're not familiar with I/O in Java, look here:
http://java.sun.com/docs/books/tutorial/essential/io/index.html

Problems with runtime.exec()

Hi All,
I am having a problem using runtime.exec()
in servlet to call a java file from the server.The server is a linux one and i am using a tomcat server-4.1.24 the server contains
some java files which i need to invoke with the help of the servlet program so i try to use exec() in servlet to invoke a particular java file in the server.The program is compiling well but no information
is displayed on the browser.Where in the servlet program i try to print the details of the particular java program that is in the server.For ur
reference i will post the code :-
import javax.servlet.http.*;
import javax.servlet.*;
import java.io.*;
public class ExeServlet extends HttpServlet
public void doGet(HttpServletRequest req,HttpServletResponse res)throws ServletException,IOException
try
String path = getServletContext().getRealPath("/var/jakarta/webapps/examples/WEB-INF/classes/ServletExample.java");
/*Where it is the path of the java file that resides in the server machine(linux)Which i want to invoke and print its details on the browser*/
Runtime runtime=Runtime.getRuntime();
Process proc=runtime.exec(path );
BufferedReader br=new BufferedReader(new InputStreamReader(proc.getInputStream()));
res.setContentType("text/html");
PrintWriter pw=res.getWriter();
pw.println("<b>");
String line=null;
while((line=br.readLine())!=null)
{ pw.println(line); //Displaying the details of the ServletExample.java file in the browser
pw.println("</b>");
catch (Exception e)
pw.println("Listener *not* started!");
What is the problem here?I was so frustrated with this.Pls. do provide an immediate reply if there is any code regarding this is working pls. do provide it.It is Urgent.I will be waiting for ur reply.
Thanx,
m.ananthu

Hi Leo,
Thank u for the reply i still have the problem with exec() in servlets.Has i said earlier in my previous mail by using exec() i trying to execute the output of a c-program for eg,Hello.run which provides an output of "HelloWorld" which is a sample eg.The Hello.run is the directory /var/jakarta/webapps/examples/WEB-INF/classes which is also the directory where my servlet program is.Where i am using a tomcat server-4.1.24 on the linux machine 7.3.Which is the server ofcourse.
Here by using a servlet program i try to exceute the Hello.run c-program and display the output in the browser.This is what i need to do.
I also used a sample core java class put the exec() there in a method and i try to call the method in the servlet.Which is also not working.
Here is that example :-
The core java program:-
public class UsingExec
public String ExeDisplay()
     try
System.out.println("ExeDisplay");
     Runtime rt=Runtime.getRuntime();
     Process p=rt.exec("/var/jakarta/webapps/examples/WEB-INF/classes/Hello.run");
p.waitFor();
return "true";
     catch(Exception e)
return "false";
public static void main(String args[])
UsingExec ue=new UsingExec();
ue.ExeDisplay();
When i run this program only ExeDisplay at the top is displayed.
Here is the Servlet program:-
import javax.servlet.http.*;
import javax.servlet.*;
import java.io.*;
public class ExeServlet extends HttpServlet
public void doGet(HttpServletRequest req,HttpServletResponse res)throws ServletException,IOException
try
res.setContentType("text/html");
PrintWriter pw=res.getWriter();
UsingExec ue=new UsingExec();
String line=ue.ExeDisplay();
pw.println(line);
catch (Exception e)
When i display this program on the browser only "false" is displayed from the UsingExec.java & nothing is displayed.
Thanx,
m.ananthu

Newbie problem with "Runtime exec" "OutputStream"

I am running an external process (Oracle Sqlplus) from a simple GUI using "Runtime exec". My problem is that I'm only able to retrieve input from the process after the Java output stream is closed. If I don't close the output stream my application does nothing. As soon as I close the output stream the input from the external process is printed to the screen and the external process is killed.
I want to be able to start the external process once and then send and receive multiple input and output streams to it without having to stop and restart the process. Currently the only way to retrieve input from the process is to close the Java output stream which closes the process.
Is this possible? Am I doing something wrong?
I am new to Java so I appreciate your help.
My code is below. I am running it on Windows 2000 Workstation, Java 1.4.1, Oracle 8.1.7.
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
class ProcessTest extends JFrame implements ActionListener {
    private JTextArea upperTextArea;
    private JTextArea lowerTextArea;
    private BufferedReader in;
    private BufferedWriter out;
    public ProcessTest() {
        initialiseComponents();
        setBounds(200, 200, 600, 400);
        setVisible(true);
    public void initialiseComponents() {
        Container contentP = getContentPane();
        contentP.setLayout(new BorderLayout());
        upperTextArea = new JTextArea("SELECT SYSDATE FROM DUAL;\n");
        lowerTextArea = new JTextArea();
        JSplitPane splitPane = new JSplitPane(JSplitPane.VERTICAL_SPLIT,
                                              new JScrollPane(upperTextArea),
                                              new JScrollPane(lowerTextArea));
        splitPane.setDividerLocation(200);
        JPanel buttonPanel = new JPanel();
        JButton runButton = new JButton("Start Process");
        runButton.addActionListener(this);
        JButton outputButton = new JButton("Write Output");
        outputButton.addActionListener(this);
        JButton flushButton = new JButton("Flush Output");
        flushButton.addActionListener(this);
        JButton closeOutputButton = new JButton("Close Output");
        closeOutputButton.addActionListener(this);
        JButton inputButton = new JButton("Read Input");
        inputButton.addActionListener(this);
        buttonPanel.add(runButton);
        buttonPanel.add(outputButton);
        buttonPanel.add(flushButton);
        buttonPanel.add(closeOutputButton);
        buttonPanel.add(inputButton);
        contentP.add(buttonPanel, BorderLayout.NORTH);
        contentP.add(splitPane, BorderLayout.CENTER);
    public void startProcess() {
        try {
            Process process = Runtime.getRuntime().exec("sqlplus -S " +
                                                         "scott/tiger");
            in = new BufferedReader(new InputStreamReader(
                                     process.getInputStream()));
            out = new BufferedWriter(new OutputStreamWriter(
                                      process.getOutputStream()));
            System.out.println("Process Started.");
        catch(IOException e) {
            e.printStackTrace();
    public void writeOutput() {
        try {
            out.write(upperTextArea.getText().toCharArray());
            System.out.println("Output Write Completed.");
        catch (IOException e) {
            e.printStackTrace();
    public void flushOutput() {
        try {
            out.flush();
            System.out.println("Output Flush Completed.");
        catch (IOException e) {
            e.printStackTrace();
    public void closeOutput() {
        try {
            out.close();
            System.out.println("Output Close Completed.");
        catch (IOException e) {
            e.printStackTrace();
    public void readInput() {
        try {
            lowerTextArea.read(in, lowerTextArea);
            System.out.println("Input Read Completed.");
        catch (IOException e) {
            e.printStackTrace();
    public void actionPerformed(ActionEvent e) {
        String action = e.getActionCommand();
        if (action.equalsIgnoreCase("start process")) {
            Thread thread1 = new Thread(){
                public void run(){
                    startProcess();
            thread1.start();
        else if (action.equalsIgnoreCase("write output")) {
            Thread thread2 = new Thread(){
                public void run(){
                    writeOutput();
            thread2.start();
        else if (action.equalsIgnoreCase("flush output")) {
            Thread thread3 = new Thread(){
                public void run(){
                    flushOutput();
            thread3.start();
        else if (action.equalsIgnoreCase("close output")) {
            Thread thread4 = new Thread(){
                public void run(){
                    closeOutput();
            thread4.start();
        else if (action.equalsIgnoreCase("read input")) {
            Thread thread5 = new Thread(){
                public void run(){
                readInput();
            thread5.start();
    public static void main(String[] args) {
        new ProcessTest();
}

At this point, I'm not getting the same results as you. I'm executing cmd.exe w/o args, and using the text area to do multiple directory listings in one go -- so far, the input thread has been able to keep up. Try copying & pasting the following below (I made a few changes to it). If it still doesn't work, it might help to know what operating system you're on, jdk version, etc..
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.io.*;
class ProcessTest extends JFrame implements ActionListener {
    private BufferedReader in;
    private BufferedWriter out;
    private JTextArea upperTextArea;
    private JTextArea lowerTextArea;
    private ProcInThread pit;
    private class ProcInThread extends Thread {
        private BufferedReader in;
        private char[] cbuf = new char[8192];
        private int numRead;
        ProcInThread(BufferedReader in) {
            this.in = in;
        public void run() {
            Thread.currentThread().setPriority(Thread.MAX_PRIORITY);
            do {
                try {
                    numRead = in.read(cbuf, 0, cbuf.length);
                    if (numRead < 0) System.out.println("\n***END OF STREAM***\n"); // <-DEBUG CODE
                } catch (IOException ex) {
                    ex.printStackTrace();
                SwingUtilities.invokeLater(new Runnable() {
                    public void run() {
                        lowerTextArea.append(new String(cbuf, 0, numRead));
            } while (numRead != -1);
            try {
                in.close();
            } catch (IOException e) {
                e.printStackTrace();
    public ProcessTest() {
        initialiseComponents();
        setBounds(200, 200, 600, 400);
        setVisible(true);
    public void initialiseComponents() {
        Container contentP = getContentPane();
        contentP.setLayout(new BorderLayout());
        upperTextArea = new JTextArea("dir\ndir\ndir\ndir\ndir\ndir\ndir\n");
        lowerTextArea = new JTextArea();
        JSplitPane splitPane = new JSplitPane(JSplitPane.VERTICAL_SPLIT,
                                              new JScrollPane(upperTextArea),
                                              new JScrollPane(lowerTextArea));
        splitPane.setDividerLocation(200);
        JPanel buttonPanel = new JPanel();
        JButton runButton = new JButton("Start Process");
        runButton.addActionListener(this);
        JButton outputButton = new JButton("Write Output");
        outputButton.addActionListener(this);
        JButton flushButton = new JButton("Flush Output");
        flushButton.addActionListener(this);
        JButton closeOutputButton = new JButton("Close Output");
        closeOutputButton.addActionListener(this);
        JButton inputButton = new JButton("Read Input");
        inputButton.addActionListener(this);
        buttonPanel.add(runButton);
        buttonPanel.add(outputButton);
        buttonPanel.add(flushButton);
        buttonPanel.add(closeOutputButton);
        buttonPanel.add(inputButton);
        contentP.add(buttonPanel, BorderLayout.NORTH);
        contentP.add(splitPane, BorderLayout.CENTER);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    public void startProcess() {
        try {
            Process process = Runtime.getRuntime().exec("cmd.exe");
            in = new BufferedReader(new InputStreamReader(
                                     process.getInputStream()),8192);
            out = new BufferedWriter(new OutputStreamWriter(
                                      process.getOutputStream()),8192);
            pit = new ProcInThread(in);
            pit.start();
            System.out.println("Process Started.");
        catch(IOException e) {
            e.printStackTrace();
    public void writeOutput() {
        try {
            out.write(upperTextArea.getText().toCharArray());
            System.out.println("Output Write Completed.");
        catch (IOException e) {
            e.printStackTrace();
    public void flushOutput() {
        try {
            out.flush();
            System.out.println("Output Flush Completed.");
        catch (IOException e) {
            e.printStackTrace();
    public void closeOutput() {
        try {
            out.close();
            System.out.println("Output Close Completed.");
        catch (IOException e) {
            e.printStackTrace();
    public void readInput() {
    public void actionPerformed(ActionEvent e) {
        String action = e.getActionCommand();
        if (action.equalsIgnoreCase("start process")) {
            Thread thread1 = new Thread(){
                public void run(){
                    startProcess();
            thread1.start();
        else if (action.equalsIgnoreCase("write output")) {
            Thread thread2 = new Thread(){
                public void run(){
                    writeOutput();
            thread2.start();
        else if (action.equalsIgnoreCase("flush output")) {
            Thread thread3 = new Thread(){
                public void run(){
                    flushOutput();
            thread3.start();
        else if (action.equalsIgnoreCase("close output")) {
            Thread thread4 = new Thread(){
                public void run(){
                    closeOutput();
            thread4.start();
        else if (action.equalsIgnoreCase("read input")) {
            Thread thread5 = new Thread(){
                public void run(){
                readInput();
            thread5.start();
    public static void main(String[] args) {
        new ProcessTest();
}

Spawn a java process using runtime.exec() method

Hi,
This is my first post in this forum. I have a small problem. I am trying to spawn a java process using Runtime.getRuntime().exec() method in Solaris. However, there is no result in this check the follwoing program.
/* Program Starts here */
import java.io.*;
public class Test {
public static void main(String args[]) {
String cmd[] = {"java", "-version"};
Runtime runtime = Runtime.getRuntime();
try{
Process proc = runtime.exec(cmd);
}catch(Exception ioException){
ioException.printStackTrace();
/* Program ends here */
There is neither any exception nor any result.
The result I am expecting is it should print the following:
java version "1.4.0"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-b92)
Java HotSpot(TM) Client VM (build 1.4.0-b92, mixed mode)
Please help me out in this regard
Thanks in advance
Chotu.

Yes your right. It is proc.getInputStream() or proc.getErrorStream(). That is what I get for trying to use my memory instead of looking it up. Though hopefully the OP would have seen the return type of the other methods and figured it out.

Problem with Runtime.exec()

Hi,
I'm having a problem with Runtime.exec() . I have a batch file with debug option to FTP the desktop file to mainframe. When I executed this in Windows it's shows me the responce from the server (like ' Transfer Completed' ) for my FTP commands. But when I launch this through java it's only shows the errors not the normal responces from the server. I need this responses to confirm the proper transfer of file.
My Java Code:
String strCommand = "cmd.exe /c " + outdirectory + batchfilename;
boolean bWait = true;
Runtime r = Runtime.getRuntime();
Process pr = r.exec(strCommand);
BufferedInputStream bis =new BufferedInputStream(pr.getInputStream ());
int c=0;
/** Outlet for IO for the process **/
while (c!=-1) {
c=bis.read();
/**Now wait for the process to get finished **/
if(bWait == true){
pr.waitFor();
pr.destroy();
My Batch file is :
FTP -n -d -s:C:\IT2.cmd > C:\tIT2.log
EXIT
Thanks
Sathiesh

Ahh, you are redirecting the standard out from the ftp command to a file, therefore no output is sendt back to your java code,
you have to redirect the stderr stream, not the stdout stream in your batch file;
FTP -n -d -s:C:\IT2.cmd 2> C:\tIT2.log(notice the "2>" instead of ">")
Now your batch file should direct the error stream to the log, and the standard output back to the java program.
(I'm used to UNIX streams, not NT, but the "2>" redirection should work on NT also I guess)

Launch Command Line Scanner with Runtime.exec()

Hi im trying to develop all the process of a common Antivirus ,
I have a command line anti-virus. But when i try to scan a single file mi code doesnt work.
I made the following code:
Runtime runtime = Runtime.getRuntime();
commands = new String[] {"cmd.exe", "/c","C:\\KAVCLineScanner\\kavecscan.exe","C:\\anfed\\a.txt"};
Process p =runtime.exec(commands);
BufferedReader b =new BufferedReader(new
InputStreamReader(p.getInputStream()));
String line=null;
while( (line=b.readLine())!=null){
System.out.println(line);
I think the problem is my parameter where i send the file to scan "C:\\anfed\\a.txt", because if i execute this instruction from MSDOS, the process doesnt have problems.
I also made a .bat file with the instructions but i have the same problem :(
Thanks for any advise

I think java naming is from programmer's point of view, so the output stream of the process would be the inputstream to the programmer, hence I am trying to write to my outputstream, which is actually the process' inputstream.

Launch Acrobat Reader with Runtime.exec() under WINNT4, without absolut pat

Hi,
I would like to launch Acrobat Reader from a Swing application. This works fine with Runtime.exec() as long as I provide the full path to the AcroRd32.exe. The problem is that I cannot predict the location of this exe on the systems of the users. Athough is in the Windows PATH, since I can launch from the windows execute-dialog, the Runtime.exec() is not able to locate the file.
How can I solve this problem?
Thanks a lot!
Horst

hey BIJ, thank you so much man. start really does wonders!! i was stuck with invoking a fortran program for last couple of days and now i went through your postings and tried with start. it did work!!
thanks again,
bhairampally

Killing Internet Browser opened with Runtime.exec

I am running Win NT 4.0 and I am successfully opening my HTML help using the following code:
String command = new String("cmd /K ");
command = command.concat("G:\editor\help\index.html");
Process p = Runtime.getRuntime().exec(command);
However, if I run p.destroy(), the browser window does not close. This means that the help remains open after the program exits and also that multiple help windows can be opened.
Does anyone know how to kill a browser opened with Runtime.exec()?
Thanks for any help you can offer,
Christopher Collins
Marineering Limited

Thanks jmschrei,
I tried System.exit(0) and Runtime.getRuntime().exit(0) and neither succeeded in closing the internet browser process. I suspect that process.destroy() and runtime.exit(0) both are killing the instance of the command interpreter spawned by runtime.exec("cmd /K URL") and not actually the browser opened by that command. Therefore, I think that the process refers to the "cmd" and not the browser, which probably opens completely independently of my Java program, thus can't be closed by it.
Unforetunately, I don't know another way to open a browser.
If anyone has any additional suggestions, I would appreciate it. Many people in the forums seem to have asked this one, and there are no solutions I could find.
Christopher

Internal processing Vs external processing with in the networks under a WBS

Dear Gurus,
please give an over view about internal processing Vs external processing with in the networks under a WBS element ,
is there any different process for creating reservatios & PRs in both the above ?
rgds

I think for internal processing the procurement indicator willbe 140 (when PR is not required) & for external processing the procurement indicator willbe 130 (when PR is required)
Regards,
Indranil

Start a new java process using Runtime.Exec() seems to ignore the -Xmx

I am working with a process that requires a minimum of 1.5 GB to run and works better if more is available.
So I am determining how much memory is available at startup and restarting the jre by calling
Runtime.exec("java -Dcom.sun.management.jmxremote=true -Xmx1500M -jar XXX.jar")
which reinvokes the same process with a new max memory size.
The initial call to the process is
java -Dcom.sun.management.jmxremote=true -Xmx3500M -jar XXX.jar
The initial call returns 3262251008 from Runtime.maxmemory()
When reinvoked through Runtime.exec() as above
Runtime.maxmemory() still returns 3262251008
Is there a way to separate the new process from the size specified by the parent process?

That is strange. Here is a program I wrote which calls itself recursively.
import java.io.IOException;
import java.io.InputStream;
import java.util.List;
import java.util.ArrayList;
import static java.util.Arrays.asList;
public class MemorySize {
    public static void main(String... args) throws IOException, InterruptedException {
        System.out.println("Maximum memory size= "+Runtime.getRuntime().maxMemory());
        if (args.length == 0) return;
        List<String> cmd = new ArrayList<String>();
        cmd.add("java");
        cmd.add("-cp");
        cmd.add(System.getProperty("java.class.path"));
        cmd.add("-Xmx"+args[0]+'m');
        cmd.add("MemorySize");
        cmd.addAll(asList(args).subList(1,args.length));
        Process p = new ProcessBuilder(cmd).start();
        readin(p.getErrorStream());
        readin(p.getInputStream());
    private static void readin(final InputStream in) {
        new Thread(new Runnable() {
            public void run() {
                try {
                    byte[] bytes = new byte[1024];
                    int len;
                    while((len = in.read(bytes))>0)
                        System.out.write(bytes, 0, len);
                    in.close();
                } catch (IOException e) {
                    e.printStackTrace();
        }).start();
}If you run this with the args 128 96 33 222 it prints out
Maximum memory size= 66650112
Maximum memory size= 133234688
Maximum memory size= 99942400
Maximum memory size= 35389440
Maximum memory size= 231014400

Problems with Runtime.exec() and certain Unix processes

Certain Unix processes don't behave correctly when run from Java using Runtime.exec(). This can be seen by running /bin/sh and trying to interact with it interactively. The issue appears to be that /bin/sh (and many other Unix tools) are checking the file handles on the spawned process to see if they are associated with a TTY.
Is there any way to associate a process spawned by Runtime.exec() with a terminal or alternatively, is there a JNI library available that would setup the process correctly and still provide access to the input and output streams?
Our objective is to have the flexibility of expect in being able to run and interact with spawned processes. A bug was opened at one point but closed back in 1997 as being a fault in the spawned process, not Java.
Bug ID: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4058689

#include <stdio.h>
void doit() {
int c;
        while((c=getc(stdin)) != EOF) {
                printf("%c",c);
int main() {
        freopen("/dev/tty", "r", stdin);
        doit();
}This program reopens its standard input against /dev/tty and catenates it to stdout. And voila, it takes its standard input from the terminal, even though it was started with stdin against /dev/null..
$ gcc b.c -o b
$./b < /dev/null
buon giorno
buon giorno

Issue with Runtime.exec() or ProcessBuilder pb.start()

I am having problem with running a separate JVM process. The finished code must be able to start and forcibly stop the spawned process. The problem I am having is that the spawned process seems to hang. I have tried reading all output from the process with no luck. The java program opens a ServerSocket on a separate thread right away. However, when this is started through Runtime.exec() or ProcessBuilder the socket does not open until the first process is terminated. I have have been looking high and low for an answer that will fix this. I could write this all as a multithreaded application, however I would really like to isolate the second process in terms of the JVM settings. I would like to be able to monitor this process directly and indirectly for failure or early termination and restart it automatically. Other Java program I run with this method experience the same problem--a hang at a variable point in execution that is not relieved until the originating process ends.
        try {
            ProcessBuilder pb = new ProcessBuilder("\"C:\\Program Files\\Java\\jre6\\bin\\java.exe\" -jar -server \"PATHTOJAR\"");
            Process p = pb.start();
            java.io.InputStream is = p.getInputStream();
            while(running) System.out.print(is.read());
        catch (java.io.IOException ioe) { ioe.printStackTrace(); }

The finished code must be able to start and forcibly stop the spawned process.Process.destroy().
I have tried reading all output from the process with no luck.No you haven't - see below.
The java program opens a ServerSocket on a separate thread right away. However, when this is started through Runtime.exec() or ProcessBuilder the socket does not open until the first process is terminated.Which of these programs is which?
ProcessBuilder pb = new ProcessBuilder("\"C:\\Program Files\\Java\\jre6\\bin\\java.exe\" -jar -server \"PATHTOJAR\"");That should be
ProcessBuilder pb = new ProcessBuilder("C:\\Program Files\\Java\\jre6\\bin\\java.exe", "-jar", "PATHTOJAR", "-server");
java.io.InputStream is = p.getInputStream();
while(running) System.out.print(is.read());(a) call ProcessBuilder.redirectErrorStream(true);
(b) the loop must stop when is.read() returns -1, and you shouldn't print that value.

Trying to run external script using Runtime.exec

Hey,
I am trying to use Runtime.exec(cmd, evnp, dir) to execute a fortran program and get back its output, however it seems to always be hanging. Here is my code snippet :
            Process process = Runtime.getRuntime().exec(
                  "./fortranCodeName > inputFile.txt" , null, new File("/home/myRunDir/"));
            InputStream stream = new InputStream(process.getInputStream());
            InputStream error = new InputStreamr(process.getErrorStream());
            BufferedReader stdoutReader = new BufferedReader(new InputStreamReader(stream));
            BufferedReader erroutReader = new BufferedReader(new InputStreamReader(error));
            System.out.println(stream.available()); //returns 0
            System.out.println(error.available());     //returns 0
            while (true) {
                String line1 = stdoutReader.readLine(); //hangs here
                String line2 = erroutReader.readLine();
                if (line1 == null) {
                    break;
                System.out.println(line1);
                System.out.println(line2);
            }I know for a fact that this fortran code prints out stuff when run it in terminal, but I don't know if I have even set up my Runtime.exec statement properly. I think I am clearing out my error and input streams with the whole reader.readLine bit I have above, but I am not sure. If you replace the command with something like "echo helloWorld" or "pwd", it prints out everything properly. I also am fairly confident that I have no environmental variables that are used in the fortran code, as I received it from another computer and haven't set up any in my bash profile.
Any Ideas?

Okay, so I implemented the changes from that website (thanks by the way for that link, it helps me understand this a little better). However, my problem is still occuring. Here is my new code:
            class StreamThread extends Thread {
            InputStream is;
            String type;
            StreamThread(InputStream is, String type)
                this.is = is;
                this.type = type;
            public void run()
                try
                    InputStreamReader isr = new InputStreamReader(is); //never gets called
                    BufferedReader br = new BufferedReader(isr);
                    String line=null;
                    while ( (line = br.readLine()) != null)
                        System.out.println(type +">"+ line);
                    } catch (IOException ioe)
                        ioe.printStackTrace();
        try {
            Process process = Runtime.getRuntime().exec(
                  "./fortranCodeName" , null, new File("/home/myRunDir/"));
            StreamThread stream = new StreamThread(process.getInputStream(), "OUTPUT");
            StreamThread errorStream = new StreamThread(process.getInputStream(), "ERROR");
            stream.start();
            errorStream.start();
            int exitVal = process.waitFor(); //hangs here
            System.out.println("ExitValue: " + exitVal);

Starting of external processes with Runtime.exec() properly

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