Building a process pipe with ProcessBuilder in Jav

Question

I've been trying to figure out how to pipe a few processes in Java using the new ProcessBuilder. I can't find a suitable example of what I want to do and when I try to do it myself the process just hangs. I would appreciate a very simple example of some code that runs the equivalent of cat test.txt | wc, but not through a shell.

--Update--

OK, just to clarify. I know there are ways to simulate a pipe by reading and writing streams. I'm wondering if that's done in some automatic way by the redirectInput and redirectOutput methods introduced in Java 7.

Answer 1

You don't need a pipe in this case.

"grep bla test.txt"

however assuming you need a pipe, you need to use a shell like bash

"/bin/bash", "-c", "grep foo text.txt | grep bar"

Answer 2

Start a child thread for each Input-/OutputStream pair with a simple copy loop in run().