Interaction with MS DOS-program

Question

I try to interact with a MS DOS-program.
I try something like this:
// start command running
startCmd = "start command";
Process proc = Runtime.getRuntime().exec(startCmd);
istr = proc.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(istr));           
printCmdLine(br);
out = proc.getOutputStream();
writer = new BufferedWriter(new OutputStreamWriter(out));
writer.write("second command");
writer.newLine();
writer.flush();
printCmdLine(br);
writer.write("third command");
writer.newLine();
writer.flush();                     
printCmdLine(br);
// wait for command to terminate
try {
     proc.waitFor();
catch (InterruptedException e) {
     System.err.println("process was interrupted");
// check its exit value
if (proc.exitValue() != 0)
     System.err.println("exit value was non-zero");
The problem is that I can't read from the InputStream:
private static void printCmdLine(BufferedReader br) throws IOException {
     ArrayList list = new ArrayList();
     String outlist[];
     String str = br.readLine();
The program can't read. The DOS prompt waits for an input from the keyboard and nothing more happens. If I don't try to read from the InputStream, the program hangs when it comes to proc.waitFor(); - The DOS prompt waits for an input from the keyboard. I can't achieve this by using a batch file either. Anyone knows how to do this?

Answer 1

1. Buffered reader/writer might not be so good an idea; use the constructor with boolean flush.
2. It might be, that you need to read from the MSDOS program's STDERR, the "error" InputStream. This can be tested in MSDOS by appending to the command-line (NT/2000) greater-than-out.txt and 2-greater-than-err.txt.