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Jan 8th, 2006

Executing dos commands in Java

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Dear all,
Could you tell me how to go about executing MSDOS commands thru Java. I tried with the Process class but it gives an error:2.
Could anyone please advise.

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can I invoke dos commands thru Java? in Java

Rajnesh

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Jan 8th, 2006

Re: Executing dos commands in Java

You should be able to use Process:

Process p = Runtime.getRuntime().exec(command);

command is a string you pass.

What's the error you're recieving?

server_crash

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Postaholic

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Jan 8th, 2006

Re: Executing dos commands in Java

The error says:
-------------------------------------------------------------------------
Exception in thread "main" java.io.IOException: CreateProcess: start error=2
at java.lang.Win32Process.create(Native Method)
at java.lang.Win32Process.<init>(Unknown Source)
at java.lang.Runtime.execInternal(Native Method)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at java.lang.Runtime.exec(Unknown Source)
at Dos.main(Dos.java:5)
------------------------------------------------------------------
The program is:
---------------------------------------
import java.io.*;

public class Dos{
public static void main(String[] args) throws IOException{
Process p = Runtime.getRuntime().exec("start");
}
}
-------------------------------------------------

Rajnesh

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Jan 9th, 2006

Re: Executing dos commands in Java

You will need to start a command interpreter in order to launch operating system level commands.
Under win32 that's done using the "cmd" command.
For example "cmd dir" would execute a dir command.

The entire system is rather tricky, I've never really gotten the hang of it (but then I've never tried to, preferring to keep my code operating system independent).

jwenting

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duckman

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Jan 9th, 2006

Re: Executing dos commands in Java

Could you please explain the steps...of what you said because I tried and i think m not on the right track.....

Rajnesh

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Jan 11th, 2006

Re: Executing dos commands in Java

Could you forwrd me tha whole prog as i did what you told, while no error is there, but no output is given

Rajnesh

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Jan 12th, 2006

Re: Executing dos commands in Java

I've done a bit more R&D (you got me interested

), turns out it's trickier than it looks because you need to start a process and then start a process in that process and catch the output of that sub process.

As a minimum you'd end up with something like this (for a simple dir command):

Java Syntax (Toggle Plain Text)
          String[] command =  new String[4];
          command[0] = "cmd";
          command[1] = "/C";
          command[2] = "dir";
          command[3] = "c:\\";
          Process p = Runtime.getRuntime().exec(command);
          BufferedReader stdInput = new BufferedReader(new 
               InputStreamReader(p.getInputStream()));
 
          BufferedReader stdError = new BufferedReader(new 
               InputStreamReader(p.getErrorStream()));
 
          // read the output from the command
 
          String s = null;
          System.out.println("Here is the standard output of the command:\n");
          while ((s = stdInput.readLine()) != null) {
              System.out.println(s);
          }
 
          // read any errors from the attempted command
 
          System.out.println("Here is the standard error of the command (if any):\n");
          while ((s = stdError.readLine()) != null) {
              System.out.println(s);
          }
          String[] command =  new String[4];
          command[0] = "cmd";
          command[1] = "/C";
          command[2] = "dir";
          command[3] = "c:\\";
          Process p = Runtime.getRuntime().exec(command);
          BufferedReader stdInput = new BufferedReader(new 
               InputStreamReader(p.getInputStream()));

          BufferedReader stdError = new BufferedReader(new 
               InputStreamReader(p.getErrorStream()));

          // read the output from the command

          String s = null;
          System.out.println("Here is the standard output of the command:\n");
          while ((s = stdInput.readLine()) != null) {
              System.out.println(s);
          }

          // read any errors from the attempted command

          System.out.println("Here is the standard error of the command (if any):\n");
          while ((s = stdError.readLine()) != null) {
              System.out.println(s);
          }

Forget the /C option (as I initially did) and it will only start a command shell and just sit there forever waiting for that to terminate (which it won't as there's nothing ever telling it to close).

jwenting

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duckman

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Jan 15th, 2009

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Re: Executing dos commands in Java

Hi Friend,
Please find the sample code below.

Runtime r = Runtime.getRuntime();
Process p = r.exec("cmd");

BufferedReader in = new BufferedReader(new
InputStreamReader(p.getInputStream()));
String inputLine="" ;
while ((inputLine = in.readLine()) != null) {

aruntells

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Nov 16th, 2009

Re: Executing dos commands in Java

Java Syntax (Toggle Plain Text)
import java.io.*;
 
public class Dos
{
public static void main(String[] args)
{
	try
          {
		String[] command =  new String[4];
          command[0] = "cmd";
          command[1] = "/C";
          command[2] = "del";
          command[3] = "d:\\a.txt";
 
          Process p = Runtime.getRuntime().exec(command);
 
          BufferedReader stdInput = new BufferedReader(new InputStreamReader(p.getInputStream()));
 
          BufferedReader stdError = new BufferedReader(new InputStreamReader(p.getErrorStream()));
 
          // read the output from the command
 
          String s = null;
          System.out.println("Here is the standard output of the command:\n");
          while ((s = stdInput.readLine()) != null) {
              System.out.println(s);
          }
 
          // read any errors from the attempted command
 
          System.out.println("Here is the standard error of the command (if any):\n");
          while ((s = stdError.readLine()) != null) {
              System.out.println(s);
          }
		System.out.println("I am In try");
	  }
 
 
	catch(Exception e){  
				System.out.println("I am In catch");
			 }
}
}
import java.io.*;

public class Dos
{
public static void main(String[] args)
{
	try
          {
		String[] command =  new String[4];
          command[0] = "cmd";
          command[1] = "/C";
          command[2] = "del";
          command[3] = "d:\\a.txt";

          Process p = Runtime.getRuntime().exec(command);

          BufferedReader stdInput = new BufferedReader(new InputStreamReader(p.getInputStream()));
 
          BufferedReader stdError = new BufferedReader(new InputStreamReader(p.getErrorStream()));
 
          // read the output from the command
 
          String s = null;
          System.out.println("Here is the standard output of the command:\n");
          while ((s = stdInput.readLine()) != null) {
              System.out.println(s);
          }
 
          // read any errors from the attempted command
 
          System.out.println("Here is the standard error of the command (if any):\n");
          while ((s = stdError.readLine()) != null) {
              System.out.println(s);
          }
		System.out.println("I am In try");
	  }


	catch(Exception e){  
				System.out.println("I am In catch");
			 }
}
}

Last edited by Nick Evan; Feb 4th, 2010 at 3:42 am. Reason: Added code-tags

prianka

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Dec 13th, 2011

Re: Executing dos commands in Java

its giving error:2.
Can any one help on this

prathimat

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