Call external command using java

Hi !
I want to call a external command in linux system with java .I am new to this ,so need help ..
Suppose a command is known as "foobar" in linux .generally executed by
$./foobar
What I was thinking is to call this using java and return the output to a file .
how do I do this ?

Take a look at ProcessBuilder.

Similar Messages

Calling external programs from Java?

Hi All,
Is there a way of calling external applications from Java without using Runtime.exec(). That method seems quite messy when you are dealing with streaming data from an input file to an output file. Basically what I'm asking is there a way to run a command the same way you would type it in a command shell?
Thanks

LeWalrus wrote:
Ok, I've an external application that I want to be called inside a Java GUI. It has several input arguements, which the format looks something like:
programname inputfile > outputfile
Simple enough.
>
Works fine from a shell command line. From what I understand, this won't work using Runtime.exec() because that method will just start the application. Works fine from Runtime.exec(). Since you are'>' to write stdout to a file you need to us a shell to execute the command.
String[] command = {"sh", "-c","programname inputfile > outputfile"};
Process process = runtime.exec(command);
You need to read, digest and implement the recommendations given in http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html .
File input and output from the application has to be taken care of programatically (java.io stuff). Fine if you've only one input and output. But if you have several input files and hundreds of output files, where does this leave you. It would be much easier if you could pass a string command to the shell directly as if you typed it in the command line yoursel!

How can I call external exe in java

Hi ,
Is It Possible to call external exe in java.
I read Runtime.exe("some exe") but actually my exe expects some input to process for that how can i pass the input to my exe and how can get the response from exe to my java class.
any sample code is welcome.
Thanks
Babu H

example
import javax.swing.*;
import java.awt.*;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.io.*;
public class RuntimeExample extends JFrame {
    private JTextArea textArea;
    private JTextField textField;
    private PrintWriter writer;
    public RuntimeExample()
        init();
        initProcess();
    public void init()
        textArea = new JTextArea(20, 80);
        textArea.setEditable(false);
        textField = new JTextField(30);
        textField.addKeyListener(new KeyAdapter()
            public void keyPressed(KeyEvent event) {
                if (event.getKeyCode() == KeyEvent.VK_ENTER)
                    if (writer != null)
                        textArea.setText("");
                        writer.print(textField.getText() + "\r\n");
                        writer.flush();
                        textField.setText("");
        Container container = getContentPane();
        JScrollPane scrollPane = new JScrollPane();
        scrollPane.setViewportView(textArea);
        container.add(scrollPane, BorderLayout.CENTER);
        container.add(textField, BorderLayout.SOUTH);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        pack();
        textField.grabFocus();
        setVisible(true);
    public static void main(String[] args) {
        new RuntimeExample();
    public void initProcess()
        Runtime rt = Runtime.getRuntime();
        try
            //Process p = rt.exec(new String [] {"cmd", "/C", textField.getText()});
            //textArea.setText("");
            //textField.setText("");
            Process p = rt.exec("cmd");
            writer = new PrintWriter(p.getOutputStream());
            Thread thread1 = new Thread(new StreamReader(p.getErrorStream()));
            Thread thread2 = new Thread(new StreamReader(p.getInputStream()));
            thread1.start();
            thread2.start();
            System.out.println("Exit Value = " + p.waitFor());
        catch (Exception ex)
            textArea.append(ex.getMessage());
            ex.printStackTrace();
    public class StreamReader implements Runnable
        InputStream is;
        public StreamReader(InputStream is)
            this.is = is;
        public void run()
            try
                BufferedReader reader = new BufferedReader(new InputStreamReader(is));
                String data;
                while ((data = reader.readLine()) != null)
                    textArea.append(data + "\n");
                reader.close();
            catch (IOException ioEx)
                ioEx.printStackTrace();
}you can pass input to the exe by using getOutputStream() from Process and get the output from getInputStream() from Process

How to call gnuplot command from java

Hi there,
In our course, we are required to develop an GUI for gnuplot. In case you don't know about gnuplot, it's a plotting program and has lots of command. We want to use java and swing, but now we don't know how to call gnuplot command from java, or how to execute a shell command(script) from java.
By the way, since we need read in files with several columns of data and allow user to select a column, we want to use JTable. Is that reasonable?
Thanks a lot for any suggestions!
Jack

Hi, there:
Will using JTable add much overhead? I may have to use several JTables and switch among them. I can add scroll bar to or edit JTables, right?
BTW, do you have experience about gnuplot? Can I find the command tree of gnuplot somewhere? Or do you know a better place to post question about gnuplot? unix/linux group, maybe.
Thanks,
Jack
P.S. Would you guys answer my question after I use up my duke dollars? :- )

What is the best way to call SSH commands through Java technologies

What is the best way to call SSH commands through Java technologies

I don't think you can specify the password at the prompt using ssh. Plink has the -pw command option for passwords. What I did was except ssh to ask me and write the password programmatically through the outputStream I obtained from my Process object. I looked for "password: ", and then wrote the password with a trailing newline.
Both plink and ssh will also ask if you trust the host if it is the first time you are connecting to it. So before just writing the password, check if the program wants verification from you: normally supplying "y" or "n". This should only have to happen the first time the client connects. It looks like thisPLINK:
The server's host key is not cached in the registry. You
have no guarantee that the server is the computer you
think it is.
The server's key fingerprint is:
1024 f8:43:61:4c:a2:5b:77:be:5b:a7:bb:1f:f7:79:b3:b7
If you trust this host, enter "y" to add the key to
PuTTY's cache and carry on connecting.
If you want to carry on connecting just once, without
adding the key to the cache, enter "n".
If you do not trust this host, press Return to abandon the
connection.
Store key in cache? (y/n)
SSH:
The authenticity of host '127.0.0.1 (127.0.0.1)' can't be established.
RSA key fingerprint is e1:02:13:c8:52:c2:23:41:9b:5b:58:2c:18:e6:59:af.
Are you sure you want to continue connecting (yes/no)?What I did was read character by character from the inputStream until I found things of interest ... like "password: ". You only need to search for this in your method which will launch the ssh or plink Process. Once you have verifyed yourself, you can just pass commands to the Process, which is an ssh connection.
My suggestion is to read() each byte from the Process's inputStream and write it to stdout. Look and see what you need to be looking for so you can interactive with the program correctly. You can't use readLine here becuase when the ssh asks for the password it does not print a newline. I do know for sure, that ssh will simply print, "passowrd: ". Plink will print this as well if the -pw option is not supplied.

Running unix command using java shows error

Hi All,
I am trying to run UNIX move command using Java exec method but its throwing error, unable to rename. Here below is the code i am trying to run to move all files from one directory to another directory. source and destination directory exists.
public class Demo
    public static void main(String args[])
        try
            Runtime rt = Runtime.getRuntime();
            Process proc = rt.exec("mv /home/demo1/* /home/demo2");
            int exitVal = proc.waitFor();
            System.out.println("Process exitValue: " + exitVal);
        } catch (Throwable t)
            t.printStackTrace();
}if i give "mv /home/demo1 /home/demo2" in exec method, its working, with * character its giving problem.
Please help me in resolving the problem.
Thank you

Characters like *, >, &, |, etc. are interpreted by the command shell--that is by the bash, zsh, etc. programs. When you execute a command with ProcessBuilder or Runtime.exec, you're not going through one of those shells, so their interpretation of those characters is not available.
In your code, the character * is being delivered directly to the mv command (which doesn't think * is anything special), as opposed to being turned into a list of files and directories as it would be when it's interpreted by the shell. The mv command doesn't know anything about the * character being special.
If you want to have those shell interpretations, you need to execute the command through a shell. One example is like so, but a) you'll want to read up on the methods in exec() that take arrays of String, and b) you'll want to read up on ProcessBuilder, and c) you'll need to check your shell's man pages to see the exact syntax and arguments.
runtime.exec("/bin/bash -c 'mv x/* y'");

How to call external files from java?

How to call external files in java. For example how to call a *.pdf file to open in its default editor(say Acrobat), or a *.html file to open in the default browser or a *.txt file in a notepad etc..,
In my program i have *.chm (Compiled Windows HTML Help) help file. how to open it in its default editor it?

Jayarathina_Madharasan wrote:
no one answered my questionHi what wrong did i do...basically insulted all the volunteers here who took the time to consider your question and try to offer you help. Other than that, you did nothing wrong.
From JavaRanch :
And even if an answer doesn't solve your problem, even if it should totally miss the point - the best thing to do to motivate others to continue trying to help you is showing respect and gratitude for the investment of time that was put into dealing with your issue.
Edited by: Encephalopathic on Apr 14, 2008 10:01 AM

Calling CL command in java

I would like to know how to call cl command in java to delete a file in my server. thanks

Use the java.lang.Runtime interface. The exec() method allows you to execute commands from the command shell:
String cmd = new String[2];
cmd[0] = "cl";
cmd[1] = fileToDelete;
Runtime rt = Runtime.getRuntime();
rt.exec(cmd);

Execute unix command using java

Hello
Can we execute a unix command using java? If it is how we can execute. Is this affect the performance of the program.
Thanks

I tried what you said. But its not working and returning error message,
java.io.IOException: CreateProcess: ls -a error=2
     at java.lang.ProcessImpl.create(Native Method)
     at java.lang.ProcessImpl.<init>(Unknown Source)
     at java.lang.ProcessImpl.start(Unknown Source)
     at java.lang.ProcessBuilder.start(Unknown Source)
     at java.lang.Runtime.exec(Unknown Source)
     at java.lang.Runtime.exec(Unknown Source)
     at java.lang.Runtime.exec(Unknown Source)
If i try this statement,
Runtime.getRuntime().exec("c\windows\notepad");
It is working fine.
Any idea about this.
Plz ...........

To run a command using java code

hi all,
There is a command
"java -jar selenium-server.jar -interactive"
which i am running through command prompt after going to D:\MyFolder\Examples .
i want to execute this command using java code .please help

subratjyetki wrote:
please answer in detail or if posible can u give the code for thisThe detail is given in the reference. Why don't you read it?
I could give you the code but it will cost you ?100 per hour.

Sudo or su command using java problem

hi im having a bit of trouble with the sudo or su command using java:
e.g.
try { Process myProcess = Runtime.getRuntime().exec("sudo ....ect"); my lil application just crashes ever time i try using this command. i know you usually have to type
password in terminal to get privileges. but since my application needs output of certain commands
i need a way to get round.
i was thinking of trying to input the password some how but im pretty much stuck as to how to do it.
thanks for the help

prometheuzz wrote:
sabre150 wrote:
:-( So I'm dumb?You probably know I wasn't serious, but just for the record: note the smiley when I posted it.:-) of course! When all other tools won't do the job then I use a hammer.

Spanish characters getting garbled while executing command using Java code

Hi,
I try to execute a command using java code. output of the command contains spanish characters. Few of these characters getting garbled after the command execution.
Runtime r = Runtime.getRuntime();
          Process p = null;
String pgm="ipconfig /all";
          try
                    p = r.exec(pgm);
BufferedReader br=new BufferedReader(new InputStreamReader
                              (p.getInputStream()));
while((val = br.readLine()) != null){ System.out.println(val);
          catch (Exception e)
                    return (null);
I tried to run the code using -Duser.language=es -Duser.region=ES -Dfile.encoding=Cp850, but this did nt help. I could see the outputs properly in command prompt,
If i redirect the output to a text file , it is getting garbled,
Please let me know to solve this issue.

884543 wrote:
Hi,
I try to execute a command using java code. output of the command contains spanish characters. Few of these characters getting garbled after the command execution.
Runtime r = Runtime.getRuntime();
          Process p = null;
String pgm="ipconfig /all";
          try
                    p = r.exec(pgm);
BufferedReader br=new BufferedReader(new InputStreamReader
                              (p.getInputStream()));
while((val = br.readLine()) != null){ System.out.println(val);
          catch (Exception e)
                    return (null);
I tried to run the code using -Duser.language=es -Duser.region=ES -Dfile.encoding=Cp850, but this did nt help. I could see the outputs properly in command prompt,
If i redirect the output to a text file , it is getting garbled,
Please let me know to solve this issue.Set the character set to UTF-8 to your InputStreamReader, for More details on usage refer the java api :
http://download.oracle.com/javase/6/docs/api/java/io/InputStreamReader.html

Creating Tail Command using Java

Hi,
When I was searching for tail command for windows I got site: http://dotnetjunkies.com/WebLog/johnwood/archive/2005/01/05/41694.aspx I think program thay have mentioned is writen in some .NET program.
So I was thinking do we have any class in Java some thing similar to FileSystemWatcher so that I can write tail command using java.
Thanks,
Ram Das

Virtual Programmer is in the to share the directory
over the Internet.No, that's a file/web server. :) I see, it's a Microsoft term.

I want run some command using java

hi all,
i want run command using java code.
from cell prompt when i run this command 'mysqldump test > /home/DBNAME.sql'
it will create DBNAME.sql file.
but i want to run this command using java code
i tried the following code but it did not work.
is any other way is their?
try {
               Runtime.getRuntime().exec("setxkbmap nudi");
          } catch(IOException ioe) {
               ioe.printStackTrace();
thanks in advance
daya

hello,
thanks for replay
i am sorry the above code should be like this.(the above code is working fine)
public class ExportTest{
     public ExportTest(){
          try {
               Runtime.getRuntime().exec("mysqldump test > '/root/DBNAME.sql'");
          } catch(IOException ioe) {
               ioe.printStackTrace();
          }catch(Exception e){
               e.printStackTrace();
     public static void main(String args[]){
          new ExportTest();
}when run above class, it not creating DBNAME.sql file.
when run in command prompt it creating DBNAME.sql
($ mysqldump test > /root/DBNAME.sql)
but i want to run this command from java code, that's way tried to do using above
code, but it won't create DBNAME.sql
is it wrong what i am doing? or any other way?
thanks inadvace
daya

Run shell commands using java program

Hi guys,
I am trying to run shell commands like cd /something and ./command with arguments as follows, but getting an exception that ./command not found.Instead of changing directory using "cd" command I am passing directory as an argument in rt,exec().
String []cmd={"./command","arg1", "arg2", "arg3"};
File file= new File("/path");
try{
Runtime rt = Runtime.getRuntime();
Process proc = rt.exec(cmd,null,file);
proc.waitFor();
System.out.println(proc.exitValue())
BufferedReader buf = new BufferedReader(new InputStreamReader(proc.getInputStream()));
catch(Exception e)
{e.printStackTrace();
So can anyone please tell me what is wrong with this approach? or is there any better way to do this?
Thanks,
Hardik

warnerja wrote:
What gives you the idea that the process to execute is called "./command"? If this is in Windows, it is "cmd.exe" for example.It does not have to be cmd.exe in Windows. Any executable or .bat file can be executed as long as one either specifies the full path or the executable is in a directory that is in the PATH.
On *nix the file has to have the executable bit set and one either specifies the full path or the executable must be in a directory that is in the PATH . If the executable is a script then if there is a hash-bang (#!) at the start of the first line then the rest of the line is taken as the interpreter to use. For example #!/bin/bash or #!/usr/bin/perl .
One both window and *nix one can exec() an interpreter directly and then pass the commands into the process stdin. The advantage of doing this is that one can change the environment in one line and it remains in effect for subsequent line. A simple example of this for bash on Linux is
import java.io.OutputStreamWriter;
import java.io.Writer;
public class ExecInputThroughStdin
    public static void main(String args[]) throws Exception
        final Process process = Runtime.getRuntime().exec("bash");
        new Thread(new PipeInputStreamToOutputStreamRunnable(process.getErrorStream(), System.err)).start();
        new Thread(new PipeInputStreamToOutputStreamRunnable(process.getInputStream(), System.out)).start();
        final Writer stdin = new OutputStreamWriter(process.getOutputStream());
        stdin.write("xemacs&\n");
        stdin.write("cd ~/work\n");
        stdin.write("dir\n");
        stdin.write("ls\n");
        stdin.write("gobbldygook\n"); // Forces output to stderr
        stdin.write("echo $PATH\n");
        stdin.write("pwd\n");
        stdin.write("df -k\n");
        stdin.write("ifconfig\n");
        stdin.write("echo $CWD\n");
        stdin.write("dir\n");
        stdin.write("cd ~/work/jlib\n");
        stdin.write("dir\n");
        stdin.write("cat /etc/bash.bashrc\n");
        stdin.close();
        final int exitVal = process.waitFor();
        System.out.println("Exit value: " + exitVal);
}One can use the same approach with Windows using cmd.exe but then one must be aware of the syntactic differences between commands running in .bat file and command run from the command line. Reading 'help cmd' s essential here.
The class PipeInputStreamToOutputStreamRunnable in the above example just copies an InputStream to an OutputStream and I use
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
public class PipeInputStreamToOutputStreamRunnable implements Runnable
    public PipeInputStreamToOutputStreamRunnable(InputStream is, OutputStream os)
        is_ = is;
        os_ = os;
    public void run()
        try
            final 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_;
}

Call external command using java

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