Notes: using ProcessBuilder API with pipelines

ProcessBuilder.java

    public static void main(String[] args) throws IOException, InterruptedException {
        String homeDirectory = System.getProperty("user.home");

        ProcessBuilder processBuilder = new ProcessBuilder("/bin/sh", "-c", "echo hello");
        ProcessBuilder processBuilder2 = new ProcessBuilder("/bin/sh", "-c", "src/script.sh");

        // inheritIO() method we see the output of a simple command in the console in our IDE.
        // use this method when we want to redirect the sub-process I/O to the standard I/O of the current process:
        processBuilder.inheritIO();
//        ProcessBuilder processBuilder = new ProcessBuilder( "node", "-v");

        // redirect any errors to stdout
        processBuilder.redirectErrorStream(true);
        File log = new File("script.log");

//        processBuilder.redirectOutput(log);
//        processBuilder.directory(new File("src"));
        Process process = processBuilder.start();

        // read stdout unless inheritIO
        String results = readStream(process.getInputStream());

        int exitCode = process.waitFor();
        System.out.println("Result: " + results + " Exit code: " + exitCode);

        // using Java 9 process builder pipelines
        List<ProcessBuilder> builders = Arrays.asList(
                new ProcessBuilder("find", "src", "-name", "*.java", "-type", "f"),
                new ProcessBuilder("wc", "-l"));

        System.out.println("testing " + readStream(startPipeline(builders).getInputStream()));
        // same works even without a pipe
//        List<ProcessBuilder> builders = List.of(
//                new ProcessBuilder("find", "src", "-type", "f"));

    }

    public static String readStream(InputStream inputStream) throws IOException {
        int bufferSize = 1024;
        char[] buffer = new char[bufferSize];
        StringBuilder out = new StringBuilder();
        Reader in = new InputStreamReader(inputStream, StandardCharsets.UTF_8);
        for (int numRead; (numRead = in.read(buffer, 0, buffer.length)) > 0; ) {
            out.append(buffer, 0, numRead);
        }
        return out.toString();
    }
    public static Process startPipeline(List<ProcessBuilder> builders) throws IOException, InterruptedException {
        List<Process> processes = ProcessBuilder.startPipeline(builders);
        Process last = processes.get(processes.size() - 1);
//        String output = readStream(last.getInputStream());
//        System.out.println("Pipeline output: " + output);
        return last;
    }