Question

How can I be notified when a process I did not start ends and is their a way to recover its exit code and or output? the process doing the watching will be running as root/administrator.

Answer 1

You can check whether a process is currently running from java by calling a shell command that lists all the current processes and parsing the output. Under linux/unix/mac os the command is ps, under windows it is tasklist.

For the ps version you would need to do something like:

ProcessBuilder pb = new ProcessBuilder("ps", "-A");
Process p = pb.start();

BufferedReader in = new BufferedReader(new InputStreamReader(p.getInputStream()));
// Skip first (header) line: "  PID TTY          TIME CMD"
in.readLine();

// Extract process IDs from lines of output
// e.g. "  146 ?        00:03:45 pdflush"
List<String> runningProcessIds = new ArrayList<String>();
for (String line = in.readLine(); line != null; line = in.readLine()) {
    runningProcessIds.add(line.trim().split("\\s+")[0]);
}

I don’t know of any way that you could capture the exit code or output.