macos - Printing my Mac's serial number in java using Unix commands

Question

I am trying to print my mac's [edit: Apple computer] serial number in a java program. I am familiar with the Unix command

ioreg -l | awk '/IOPlatformSerialNumber/ { print $4;}'

which accomplishes this task in terminal.
When I try

String command = "ioreg -l | awk '/IOPlatformSerialNumber/ { print $4; }'"
Runtime terminal = Runtime.getRuntime(); 
String input = new BufferedReader(
    new InputStreamReader(
        terminal.exec(commands).getInputStream())).readLine();
System.out.println(new BufferedReader(
    new InputStreamReader(
        terminal.exec(command, args).getInputStream())).readLine());

my serial number is not printed. Instead it prints:

<+-o Root class IORegistryEntry, id 0x100000100, retain 10>  

I think the problem is that terminal.exec() is not meant to take the whole command string. Is there something in java similar to the argument shell = True in python's Popen(command, stdout=PIPE, shell=True) that will allow me to pass the whole command string?

Answer 1

I see two possibilities:

1. Parse the output of ioreg -l using, say, Scanner.

2. Wrap the command in a shell script and exec() it:

#!/bin/sh
ioreg -l | awk '/IOPlatformSerialNumber/ { print $4;}'

Addendum: As an example of using ProcessBuilder, and incorporating a helpful suggestion by Paul Cager, here's a third alternative:

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class PBTest {

    public static void main(String[] args) {
        ProcessBuilder pb = new ProcessBuilder("bash", "-c",
            "ioreg -l | awk '/IOPlatformSerialNumber/ { print $4;}'");
        pb.redirectErrorStream(true);
        try {
            Process p = pb.start();
            String s;
            // read from the process's combined stdout & stderr
            BufferedReader stdout = new BufferedReader(
                new InputStreamReader(p.getInputStream()));
            while ((s = stdout.readLine()) != null) {
                System.out.println(s);
            }
            System.out.println("Exit value: " + p.waitFor());
            p.getInputStream().close();
            p.getOutputStream().close();
            p.getErrorStream().close();
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }
}