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Starting a process with inherited stdin/stdout/stderr in Java 6

Asked 2008-09-13T03:27:59.720
28

If I start a process via Java's ProcessBuilder class, I have full access to that process's standard in, standard out, and standard error streams as Java InputStreams and OutputStreams. However, I can't find a way to seamlessly connect those streams to System.in, System.out, and System.err.

It's possible to use redirectErrorStream() to get a single InputStream that contains the subprocess's standard out and standard error, and just loop through that and send it through my standard out—but I can't find a way to do that and let the user type into the process, as he or she could if I used the C system() call.

This appears to be possible in Java SE 7 when it comes out—I'm just wondering if there's a workaround now. Bonus points if the result of isatty() in the child process carries through the redirection.

java io process pipe
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12

A variation on John's answer that compiles and doesn't require you to use Commons IO:

private static void pipeOutput(Process process) {
    pipe(process.getErrorStream(), System.err);
    pipe(process.getInputStream(), System.out);
}

private static void pipe(final InputStream src, final PrintStream dest) {
    new Thread(new Runnable() {
        public void run() {
            try {
                byte[] buffer = new byte[1024];
                for (int n = 0; n != -1; n = src.read(buffer)) {
                    dest.write(buffer, 0, n);
                }
            } catch (IOException e) { // just exit
            }
        }
    }).start();
}
answered 2009-10-15T04:25:18.363

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