java shell for executing/coordinating processes?

Question

I know about using Runtime.exec, you pass it a native program to run + arguments. If it\'s a regular program, you can run it directly. If it\'s a shell script, you have to r

Answer 1

You can use the ProcessBuilder API provided by java.

Runtime.getRuntime().exec(...) take either an array of strings or a single string. The single-string overloads of exec() will tokenise the string into an array of arguments, before passing the string array onto one of the exec() overloads that takes a string array. The ProcessBuilder constructors, on the other hand, only take a varargs array of strings or a List of strings, where each string in the array or list is assumed to be an individual argument. Either way, the arguments obtained are then joined up into a string that is passed to the OS to execute.

Find more details at the below link Difference between ProcessBuilder and Runtime.exec()

Sample program to execute the commands.

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.lang.reflect.Field;
import java.util.List;

public class ProcessBuilderTest {
    static ProcessBuilder processBuilder = null;
    static Process spawnProcess = null;
    static int exitValue;
    static int pid;
    static List commands;

    public static void main(String[] args) {
        runSqoop();
    }

    public static void runSqoop() {
        String[] commands = { "ssh", "node", "commands" };
        processBuilder = new ProcessBuilder(commands);
        try {
            System.out.println("Executing " + commands.toString());
            spawnProcess = processBuilder.inheritIO().start();
            try {
                exitValue = spawnProcess.waitFor();
                pid = getPID(spawnProcess);
                System.out.println("The PID is " + pid);
            } catch (InterruptedException e) {
                System.out.println(e.getMessage());
            } catch (Exception e) {
                System.out.println(e.getMessage());
            }
            System.out.println("Process exited with the status :" + exitValue);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static int getPID(Process process) {
        try {
            Class processImplClass = process.getClass();
            Field fpid = processImplClass.getDeclaredField("pid");
            if (!fpid.isAccessible()) {
                fpid.setAccessible(true);
            }
            return fpid.getInt(process);
        } catch (Exception e) {
            System.out.println(e.getMessage());
            return -1;
        }
    }

}