Backgrounding Runtime.exec

Is there a way to background a Runtime.exec() call to a batch file? What I want to do is right after the batch file is executed I want to exit java and keep the .bat process running in the background. I am creating a process that lets the user upgrade a local JVM in the directory. But you can't necessarily do that from java. So I have a .bat file that extracts the necessary files. Any suggestions on how to background that?

Hmmm as far as i know the Process created by Runtime.getRuntime.exec(String ex), runs independantly of the creator. And that is also what i get from reading the Process API, espacially this part "The subprocess is not killed when there are no more references to the Process object, but rather the subprocess continues executing asynchronously":
API BEGIN
The Runtime.exec methods create a native process and return an instance of a subclass of Process that can be used to control the process and obtain information about it. The class Process provides methods for performing input from the process, performing output to the process, waiting for the process to complete, checking the exit status of the process, and destroying (killing) the process.
The Runtime.exec methods may not work well for special processes on certain native platforms, such as native windowing processes, daemon processes, Win16/DOS processes on Microsoft Windows, or shell scripts. The created subprocess does not have its own terminal or console. All its standard io (i.e. stdin, stdout, stderr) operations will be redirected to the parent process through three streams (Process.getOutputStream(), Process.getInputStream(), Process.getErrorStream()). The parent process uses these streams to feed input to and get output from the subprocess. Because some native platforms only provide limited buffer size for standard input and output streams, failure to promptly write the input stream or read the output stream of the subprocess may cause the subprocess to block, and even deadlock.
The subprocess is not killed when there are no more references to the Process object, but rather the subprocess continues executing asynchronously.
There is no requirement that a process represented by a Process object execute asynchronously or concurrently with respect to the Java process that owns the Process object.
API END
Poul Krogh

Similar Messages

How to make Runtime.exec call Linux exec?

Howdy,
I am trying to use a combination of 'find' and 'rm' to delete all files with a certain extension in a directory and all of its subdirs.
Here's the command:
Process proc = runtime.exec("find " + dir + " -name '*.vcs' -exec rm -rf {} \\;");
It's failing, not sure why, the exitCode is 1 instead of 0. I'm not sure if it's because I have to escape the '\' character, or if it's because I am calling Linux's 'exec' function within a Java exec() call, or something else entirely.
The easiest thing to do would be to just use rm, but that doesn't seem to be an option. With rm it seems to be all or nothing -- If I try:
rm -rf *.vcs
it fails if it doesn't find a file with that extension in the start directory (even though I've specified -r). But if I enter:
rm -rf *
it nukes my directories AND files, something I don't want to happen. I realize this is a Linux thing, I'm just explaining it here as background, just in case.
Anyway, so is there a way to do this? Perhaps with another system call, without using Linux's exec()?
Many thanks
Bob

import java.io.*;
public class ExecutingALinuxCommand
    static class PipeInputStreamToOutputStream implements Runnable
        PipeInputStreamToOutputStream(InputStream is, OutputStream os)
            is_ = is;
            os_ = os;
        public void run()
            try
                byte[] buffer = new byte[1024];
                for(int count = 0; (count = is_.read(buffer)) >= 0;)
                    os_.write(buffer, 0, count);
            catch (IOException e)
                e.printStackTrace();
        private final InputStream is_;
        private final OutputStream os_;
    public static void main(String[] args)
        try
            String dir = System.getProperty("user.home") + "/work/dev";
            String[] command = {"sh","-c", "find " + dir + " -name '*.java' -exec grep -l Runtime {} \\;"};
            final Process process = Runtime.getRuntime().exec(command);
            new Thread(new PipeInputStreamToOutputStream(process.getInputStream(), System.out)).start();
            new Thread(new PipeInputStreamToOutputStream(process.getErrorStream(), System.err)).start();
            int returnCode = process.waitFor();
            System.out.println("Return code = " + returnCode);
        catch (Exception e)
            e.printStackTrace();
}

Runtime.exec input problem

Hi
My requirement is, run the command using Runtime.exec(), and provide the input "Y"/"N" and get the output of the command and process .
I am able to give the input to Runtime.exec() and get the output of the command.
To provide input to Runtime.exec() I am using as follows
String input="Y";
out.write(input.getBytes()); ( OutputStream of Runtime.exec() )
out.flush();
After providing input as above , i am able read the output of the command [ using InputStream.read() ],
it works fine in Windows, Solaris, HP-UX IPF, In case of Linux(X86) or Linux IPF i am not able to read the output of the command.
I analysed the problem and found that InputSream.read() call is blocked since input of the command not provided completely. then I did as follows,
String input="Y"+Lineseperator
out.write(input.getBytes()); ( OutputStream of Runtime.exec() )
out.flush();
Then it is working fine.....( I am able to get the output of the command)
Plz help me what is background of this.

Indeed, there are buffers involved both ways. The flush() should actually flush() the output buffer, at least so much as to shove the data into the other program. But if this other program reads input line by line, than it will not take notice of the data until the end-of-line marker is also received. Some old software is buggy enough to even ignore the last line of input if it is not properly terminated by an end-of-line marker, so a close() without preceeding end-of-line may not work.
In general, controlling some program by feeding its input and reading its output can be quite tricky. Flushing first and then checking for input in a single thread may block, if some buffer size is too small.
Harald.

Java Runtime.exec running java problem

Hi, I have a simple server application, which I would like to run in the background. The following line works for me:
Runtime.getRuntime().exec("cmd /c start java -jar ..\\server\\server.jar -Dlog4j.configuration=file:src\\test\\resources\\log4j.properties -filename src\\test\\resources\\server.properties");But it displays the cmd window and I am unable to destroy it. So I would like to use
Runtime.getRuntime().exec("java -jar ..\\server\\server.jar -Dlog4j.configuration=file:src\\test\\resources\\log4j.properties -filename src\\test\\resources\\serverIntegration.properties");But it simply doesn't connect to the server. That means, it starts some java process in the background, but my client fails to communicate (i dont know whether the server doesnt respond or the client fails to send the message, but still, with the cmd /c start it works). So why is that?
A related question. How do I end the process? It is a server that "doesn't end". So I have to kill it and I would assume, that running the java only command would be capable to be destroyed, but with the cmd I have no luck there. I have already tried full paths and the overload of exec with String[] params.

Read [_When Runtime.exec() won't_|http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html].
One reason why your server doesn't run is that it might be writing stuff to stdout (a.k.a System.out). And if your process doesn't read the newly created process' stdout, then that other process will block until something is read (which will be never).
Read all of the pages of that article and follow its suggestions.

Runtime.exec() - how to open new window for new program?

Hi,
I have searched through the forums but haven't found an answer to this one yet. I am using runtime.exec() to start up a new java program. At first I thought it wasn't running properly but, after checking task manager, I have discovered that the new program I open runs, it is just completely invisible to me. I am wondering how I can get the new program to run in a command window or something where I can monitor it.
Thank you for your help,
Drew

Thank you all. After trying to figure out why the start command wouldn't work in the runtime.exec() call(not an executable - I am a dolt), I tried putting it in a batch file and it worked perfectly. Thanks for your help,
Drew

How to capture Runtime.exec() output? doesn't seem to work?

This is the first time I've used Runtime.exec();
Here's the code:
Runtime rt = Runtime.getRuntime();
            process = rt.exec(jobCommand);
            BufferedReader input = new BufferedReader(new InputStreamReader(process.getInputStream()));
            String line=null;
            while((line=input.readLine()) != null) {
                 System.out.println("OUTPUT: " + line);
            int exitVal = process.waitFor();
        } catch(Exception e) {
             e.printStackTrace();
        }//end catchas you can see, this is just copied and pasted out of the standard example for this method.
When it gets to the line:
while((line=input.readLine()) != null)
it doesn't read anything. However, when i run the SAME exact command from the windows CMD prompt i get a ton of output.
what am i doing wrong here?
thanks.

Welcome to the forum!
>
as you can see, this is just copied and pasted out of the standard example for this method.
>
No one can see that - you didn't post a link to the example you said you copied.
>
it doesn't read anything. However, when i run the SAME exact command from the windows CMD prompt i get a ton of output.
>
No one can see what command you are talking about; you didn't post the commnd or even describe what output you expect to get.
>
what am i doing wrong here?
>
What you are doing wrong is not providing the code you are using, the command you are using or enough information about what exactly you are doing.
No one can try to reproduce your problem based on what you posted.

How to display Runtime.exec() command line output via swing

Hi all, I'm new to java but have a pretty good understanding of it. I'm just not familiar with all the different classes. I'm having trouble capturing the output from a command I'm running from my program. I'm using Runtime.exec(cmdarray) and I'm trying to display the output/results to a JFrame. Once I get the output to display in a JFrame, I'd like it to be almost like a java command prompt where I can type into it incase the command requires user interaction.
The command executes fine, but I just don't know how to get the results of the command when executed. The command is executed when I click a JButton, which I'd like to then open a JFrame, Popup window or something to display the command results while allowing user interaction.
Any examples would be appreciated.
Thank you for your help in advance and I apologize if I'm not clear.

You can get the standard output of the program with Process.getInputStream. (It's output from the process, but input to your program.)
This assumes of course that the program you're running is a console program that reads/writes to standard input/output.
In fact, you really should read from standard output and standard error from the process you start, even if you're not planning to use them. Read this:
When Runtime Exec Won't

Using Runtime exec() to open and close process like java or javac

Hi, I m a student who is learning IT and is wondering if
Runtime exec() can run and stop commands like java and javac?
Can someone post the code to do so here?Thank you

Well, Here is my complete code:
import java.util.*;
import java.io.*;
import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
class StreamGobbler extends Thread
InputStream is;
String type;
StreamGobbler(InputStream is, String type)
this.is = is;
this.type = type;
public void run()
try
InputStreamReader isr = new InputStreamReader(is);
BufferedReader br = new BufferedReader(isr);
String line=null;
while ( (line = br.readLine()) != null)
System.out.println(type + ">" + line);
} catch (IOException ioe)
ioe.printStackTrace();
class Program implements Runnable
     Process proc;
String args[];
     String[] cmd = new String[4];
     boolean isGone=false;
     public Program(String args[])
          this.args=args;
     public void run()
          if (isGone==true)
               try
                    Runtime.getRuntime().exec(cmd).destroy();
               catch(IOException e)
                    System.out.println("Error: "+e.toString());
               System.out.println("User abort");
     public void start(String args[])
          if (args.length < 1)
System.out.println("USAGE: java GoodWindowsExec <cmd>");
System.exit(1);
try
String osName = System.getProperty("os.name" );
if( osName.equals( "Windows NT" ) )
cmd[0] = "cmd.exe" ;
cmd[1] = "/C" ;
cmd[3] = args[0];
else if( osName.equals( "Windows 95" ) ||osName.equals( "Windows 98" ))
cmd[0] = "command.com" ;
cmd[1] = "/C" ;
cmd[2] = args[0];
                    cmd[3]=args[1];
Runtime rt = Runtime.getRuntime();
// System.out.println("Execing " + cmd[0] + " " + cmd[1]
// + " " + cmd[2]+" "+args[1]);
proc = rt.exec(cmd);
// any error message?
StreamGobbler errorGobbler = new
StreamGobbler(proc.getErrorStream(), "ERROR");
// any output?
StreamGobbler outputGobbler = new
StreamGobbler(proc.getInputStream(), "OUTPUT");
// kick them off
errorGobbler.start();
outputGobbler.start();
// any error???
// int exitVal = proc.waitFor();
//System.out.println("ExitValue: " + exitVal);
} catch (Throwable t)
t.printStackTrace();
     public void destroy()
          isGone=true;
class test1 implements ActionListener
     String s[]={"c:\\jdk1.3\\bin\\java.exe","ContactProcessor1"};
     GUI g=new GUI();
          Program p=new Program(s);
     public test1()
          //didnt work
          g.getStart().addActionListener(this);
          g.getStop().addActionListener(this);
          g.show();
     public void actionPerformed(ActionEvent e)
          if (e.getSource()==g.getStart())
               p.start(s);
               p.run();
          if (e.getSource()==g.getStop())
               p.destroy();
               p.run();
     public static void main(String args[])
          test1 t = new test1();
class GUI extends JFrame
     JButton start;
     JButton stop;
     public GUI()
          super();
          getContentPane().setLayout(new FlowLayout());
          start=new JButton("start");
          stop=new JButton("stop");
          getContentPane().add(start);
          getContentPane().add(stop);
          setSize(100,100);
     public JButton getStart()
          return start;
     public JButton getStop()
          return stop;
}

Error in opening a file with name in chinese characters with Runtime.exec

The issue at hand is when I try to open a file with file name containing chinese characters in a localized environment in Windows through the following java code:
Runtime.exec("rundll32 SHELL32.DLL,ShellExec_RunDLL {File_With_FileName_containing_Chinese_character}");
the following error is thrown by windows.
Cannot open file "C:\??.txt".
with the exception
java.io.IOException: CreateProcess: [Ljava.lang.String;@f5da06 error=2
        at java.lang.Win32Process.create(Native Method)
        at java.lang.Win32Process.<init>(Win32Process.java:66)
        at java.lang.Runtime.execInternal(Native Method)
        at java.lang.Runtime.exec(Runtime.java:566)
        at java.lang.Runtime.exec(Runtime.java:428)
        at java.lang.Runtime.exec(Runtime.java:364)
        at java.lang.Runtime.exec(Runtime.java:326)
        at Launcher.main(Launcher.java:26)
When I try to use the same command (shown below) from the Windows Run command, the file opens sucessfully
rundll32 SHELL32.DLL,ShellExec_RunDLL {File_With_FileName_containing_Chinese_character}
Please suggest.
Thanks in advance

This may be a file association problem. To solve that:
In Windows 7:
1. Right-click the file,
2. Select "Open With"
select [Your Program Here]
3. Check always use this program.
In Windows XP:
1. Locate the file as you have described above
2. Right click the file
3. Select Open with from the pop-up menu
4. Click Choose default program…
5. Select Excel in the Recommended Programs box
6. Check Always use the selected program to open this kind of file
7. Click on OK.
1. Make Excel not available from Office 2007 listed under Programs and Features in Control Panel.
2. Take a registry backup using the steps given here
3. In the registry editor window expand HKEY_CLASSES_ROOT and navigate to .xls right and delete it.
4. Exit Registry Editor
5. Undo Step 1 to make Excel available.
6. Restart the computer and verify it the issue is fixed.
If this answer solves your problem, please check Mark as Answered. If this answer helps, please click the Vote as Helpful button. Cheers, Shane Devenshire

The Runtime.exec methods doesn't work well on Solaris ???

I have two threads and I set the different running time.
I use Runtime.exec to a run the command and use Process to get the process.
It works properly in the windows2000 platform.
However, when I transfer the platform to Solaris...and run the program...
Two threads always at the same time....It is very wired....I always debug
for 2 days....
(at first I run "vmstat 1 2" command, later I change to "ls","rmdir"....etc,
all of them don't work.....
If I close the Runtime.exec..........Everything works well......)
And I study the API. I found this message...
The Runtime.exec methods may not work well for special processes on certain
native platforms, such as native windowing processes, daemon processes,
Win16/DOS processes on Win32, or shell scripts. The created subprocess does
not have its own terminal or console.
Could someone share her/his experience.....:(
And if any other way I can run command inside java code instead of
Runtime.exec.....???
Please reply my mail to [email protected] I do appreciate your kindly &
great help!!!!!!!!
This is my code.......
import java.io.*;
import java.lang.*;
import java.util.*;
* <p>ServerThread1</p>
* <p>??�X???��?�D???�X???, "Vmstat 1 2".</p>
class ServerThread1 extends Thread{
private ServerAgent Sa;
public ServerThread1 (String Name, ServerAgent Sa){
super(Name);
this.Sa = Sa; file://Assign ServerAgent reference Sa
public void run(){
while(true){
try{
Thread.sleep(5000);
catch (Exception e){
System.out.println("ServerThread1 fails");
System.out.println("Thread1 is running.");
try {
Runtime rt1 = Runtime.getRuntime();
Process proc1 = rt1.exec("mkdir"); ------>If I close
rt1.exec , two threads works seperately...........:(
catch (Exception e) {
System.out.println("Thread1 Error");
class ServerThread2 extends Thread{
private ServerAgent Sa;
public ServerThread2 (String Name, ServerAgent Sa){
super(Name);
this.Sa = Sa;
public void run(){
while(true){
try{
Thread.sleep(15000);
catch (Exception e){
System.out.println("ServerThread2 fails");
System.out.println("Thread2 is running.");
try {
Runtime rt2 = Runtime.getRuntime();
Process proc2 = rt2.exec("vmstat 1 2"); ----->If I don't run
the rt2.exe, two threads work seperately....
catch (Exception e) {
System.out.println("Thread2 Error");
public class ServerAgent{
private Vector v1 = new Vector();
private Vector v2 = new Vector();
private Hashtable currentData = new Hashtable();
private static String startUpSwap = null;
private static String startUpMem = null;
public static void main(String[] arg) {
ServerAgent s = new ServerAgent();
ServerThread1 st1 = new ServerThread1("Thread1",s);
ServerThread2 st2 = new ServerThread2("Thread2",s);
st1.start();
st2.start();

If I close the Runtime.exec..........Everything works
well......)You don't empty the output of the command, that blocks the process.
A citation from
http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html
Why Runtime.exec() hangs
The JDK's Javadoc documentation provides the answer to this question:
Because some native platforms only provide limited buffer size for standard input and output streams, failure to promptly write the input stream or read the output stream of the subprocess may cause the subprocess to block, and even deadlock.
Try out something like this:
String s;
try {
   Process myProcess =
   Runtime.getRuntime().exec("ls -l"));
   DataInputStream in = new DataInputStream(
          new BufferedInputStream(myProcess.getInputStream()));
    while ((s = in.readLine()) != null) {
        out.println(s);
catch (IOException e) {
    out.println("Error: " + e);
}Another source of trouble under Unix is not having the correct permission for that user that executes the Java VM, which will be the permissions for the spawned subprocess. But this probably not the case, as you see something after exit.
Regards,
Marc

How to give path in Runtime. exec( )

Hi,
I am trying to create an user interface, in which, it should open a different file (for example, example.doc)when a button is clicked in the applet. let us say, the path for example.doc is "C:\\WINDOWS\\DeskTOP\\folder1".
I tried with the following code
Runtime.getRuntime().exec("C:\\WINDOWS\\Desktop\\folder1\\example.doc");
but, when I click on the button it is not opening example file and I am getting an exception. I am using Runtime.exec() command for the first time.Anybody can help me with this???

Since when was a document an executable? The main problem is many people think Runtime.exec () is the same thing as the command line. The answer is, it's not. Typing "example.doc" in the windows terminal emulator (also known as cmd.exe in Windows 2000/XP or command.com in others) will work because example.doc is opened with the application configured to open files with the ".doc" extension.
However, files ending with ".doc" are not executables. If you wish to open a ".doc" file with the associated application, try this: Runtime.getRuntime ().exec ("cmd /c example.doc"); Not that I don't know if this will work with command.com as I haven't tried, but it should work with cmd.exe without problems.
Hope it helps.
Cheers

Runtime.exec() - Need to execute unix command through pipe

I want to execute something like this from Runtime.exec() :
tar -czp -C /tmp/ myfile | ssh -qx -c blowfish remoteHost tar -xz -C /tmp/
If I give the complete string as it is, then the system takes ssh command and the arguments to ssh (-qx) as arguments for tar and, thus, fails. I guess the reason is that the Runtime just takes the first string as the command and passes everything else as arguments to the command.
How can I achieve this?

The pipe symbol is interpreted by the shell, so you'd need the command you execute to be a shell (/bin/sh, /bin/csh /bin/bash, etc.) and the rest of it to be the args to that shell.
Look at the man page for your shell. There should be a -c or somesuch argument that means "take the rest of this line as a command to execute in the shell I'm creating, which will then execute."
Something like /bin/bash -c foo \| bar Not sure if you have to escape the pipe or not. Futz around with it and see.

How can I run Runtime.exec command in Java To invoke several other javas?

Dear Friends:
I met a problem when I want to use a Java program to run other java processes by Runtime.exec command,
How can I run Runtime.exec command in Java To invoke several other java processes??
see code below,
I want to use HelloHappyCall to call both HappyHoliday.java and HellowWorld.java,
[1]. main program,
package abc;
import java.util.*;
import java.io.*;
class HelloHappyCall
     public static void main(String[] args){
          try
               Runtime.getRuntime().exec("java -version");
               Runtime.getRuntime().exec("cmd /c java HelloWorld "); // here start will create a new process..
               System.out.println("Never mind abt the bach file execution...");
          catch(Exception ex)
               System.out.println("Exception occured: " + ex);
} [2]. sub 1 program
package abc;
import java.util.*;
import java.io.*;
class HelloWorld
     public static void main(String[] args){
     System.out.println("Hellow World");
} [3]. Sub 2 program:
package abc;
import java.util.*;
import java.io.*;
class HappyHoliday
     public static void main(String[] args){
     System.out.println("Happy Holiday!!");
} When I run, I got following:
Never mind abt the bach file execution...
I cannot see both Java version and Hellow World print, what is wrong??
I use eclipse3.2
Thanks a lot..

sunnymanman wrote:
Thanks,
But How can I see both programs printout
"Happy Holiday"
and
"Hello World"
??First of all, you're not even calling the Happy Holiday one. If you want it to do something, you have to invoke it.
And by the way, in your comments, you mention that in one case, a new process is created. Actually, new processes are created each time you call Runtime.exec.
Anyway, if you want the output from the processes, you read it using getInputStream from the Process class. In fact, you really should read that stream anyway (read that URL I sent you to find out why).
If you want to print that output to the screen, then do so as you'd print anything to the screen.
in notepad HelloWorld.java, I can see it is opened,
but in Java, not.I have no idea what you're saying here. It's not relevant whether a source code file is opened in Notepad, when running a program.

How to capture output of java files using Runtime.exec

Hi guys,
I'm trying to capture output of java files using Runtime.exec but I don't know how. I keep receiving error message "java.lang.NoClassDefFoundError:" but I don't know how to :(
import java.io.*;
public class CmdExec {
public CmdExec() {
public static void main(String argv[]){
     try {
     String line;
     Runtime rt = Runtime.getRuntime();
     String[] cmd = new String[2];
     cmd[0] = "javac";
     cmd[1] = "I:\\My Documents\\My file\\CSM\\CSM00\\SmartQ\\src\\E.java";
     Process proc = rt.exec(cmd);
     cmd = new String[2];
     cmd[0] = "javac";
     cmd[1] = "I:\\My Documents\\My file\\CSM\\CSM00\\SmartQ\\src\\E";
     proc = rt.exec(cmd);
     //BufferedReader input = new BufferedReader(new InputStreamReader(p.getInputStream()));
     BufferedReader input = new BufferedReader(new InputStreamReader(proc.getErrorStream()));
     while ((line = input.readLine()) != null) {
        System.out.println(line);
     input.close();
    catch (Exception err) {
     err.printStackTrace();
public class E {
    public static void main(String[] args) {
        System.out.println("hello world!!!!");
}Please help :)

Javapedia: Classpath
How Classes are Found
Setting the class path (Windows)
Setting the class path (Solaris/Linux)
Understanding the Java ClassLoader
java -cp .;<any other directories or jars> YourClassNameYou get a NoClassDefFoundError message because the JVM (Java Virtual Machine) can't find your class. The way to remedy this is to ensure that your class is included in the classpath. The example assumes that you are in the same directory as the class you're trying to run.
javac -classpath .;<any additional jar files or directories> YourClassName.javaYou get a "cannot resolve symbol" message because the compiler can't find your class. The way to remedy this is to ensure that your class is included in the classpath. The example assumes that you are in the same directory as the class you're trying to run.

How to capture output from Runtime.exec() ?

Hi,
Well, the question is in the subject ...
I'd like to capture the output of a process ran by Runtime.exec() in order to process it.
thanks,
ionel

Okay ...
Sorry for the post !
I found the solution : Runtime.exec().getOutputStream()
Thanks however
ionel

Backgrounding Runtime.exec

Similar Messages

Maybe you are looking for