Embeded command line doesn't work

Question

Can you tell me why this doesn't work
It won't work when there is a | or > involved in the syntax
Runtime rt;
Process prs;
prs = rt.exec("tifftopnm sample.tif | gocr -");
OR
prs = rt.exec("ls > outputFile");
And this example will worked fine.
prs = rt.exec("ls -alt");
Thanks,
Tom

Answer 1

I use an alternative form of exec()
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[] command = {"sh","-c","ls > /home/sabre/out"};
            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();
}