Hello all
I want to run linux command "ps | grep user" from java program and then writing output from this to a file . How can i do this ?

Thanks

 

 

import java.io.*;
 
public class Fred401
{    
    public static void main(String[] args)
    {
        try
        {
            String[] command = {"sh","-c","ps -elf | grep sabre"};
            final Process process = Runtime.getRuntime().exec(command);
            new Thread()
            {
                public void run()
                {
                    try{
                        InputStream is = process.getInputStream();
                        byte[] buffer = new byte[1024];
                        for(int count = 0; (count = is.read(buffer)) >= 0;)
                        {
                            System.out.write(buffer, 0, count);
                        }
                    }
                    catch(Exception e)
                    {
                        e.printStackTrace();
                    }
                }
            }.start();
            new Thread()
            {
                public void run()
                {
                    try{
                        InputStream is = process.getErrorStream();
                        byte[] buffer = new byte[1024];
                        for(int count = 0; (count = is.read(buffer)) >= 0;)
                        {
                            System.err.write(buffer, 0, count);
                        }
                    }
                    catch(Exception e)
                    {
                        e.printStackTrace();
                    }
                }
            }.start();
            
            int returnCode = process.waitFor();
            System.out.println("Return code = " + returnCode);
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
    }
}

 

 

Hi sabre,

awesome chunk of code there.. I have used it in a fwe of my projects (I have of course given you credit in the about dialog, and in the comments of the code)

The thing is, I am working on somthign a bit more complex now, and I'm really stuck, so I was hoping you could help.

When I use this code, I always remove the line:

[String[] command = {"sh","-c","ps -elf | grep sabre"};

and have it get the command from the constructor....


What I need now though, is to be able to get your method to return the console result from the command... so I want to be able to do this:

Public void whatWineVersion(){
runLinuxCommand("wine --version"); //runLinuxCommand is your method
system.out.println(output from the ruinLinuxCommand output)
}

Normally I would be able to do this myself, but because your method uses nested threads, I can't figure out how to get the output!

Message was edited by:
guardian07

 

 

Just perform the read of stdout in the thread used to to execute the exec(). You don't need to use a separate thread for it; in my original I just used a separate thread to show how it could be done in a separate thread.

Make sure you start the stderr thread before you start reading from stdout.