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Robot

Java awt Robot class is used to generate input events. It is used for tests automation and app that need mouse and keyboard control. Use robot to move mouse 1 pixel. 
 
import java.awt.MouseInfo;
import java.awt.Robot;
import java.awt.Point;

class RobotApp {

    public static void main(String[] args) throws AWTException {
        Robot robot = new Robot();
        while(true) {
            robot.delay(1000 * 3);
            Point pos = MouseInfo.getPointerInfo().getLocation();
            robot.mouseMove(pos.x + 1, pos.y + 1);
            System.out.println("Mouse moved");
        }
    }
}
Switch focus ALT+TAB between open applications. 
 
import java.awt.AWTException;
import java.awt.Robot;
import java.awt.event.KeyEvent;

class RobotApp {

    public static void main(String[] args) throws AWTException {
        Robot robot = new Robot();
        while(true) {
            robot.delay(1000 * 5);
            robot.keyPress(KeyEvent.VK_ALT);
            robot.keyPress(KeyEvent.VK_TAB);
            robot.keyRelease(KeyEvent.VK_ALT);
            robot.keyRelease(KeyEvent.VK_TAB);
        }
    }
}

EXEC

Open application using exec() runtime method. 
 
import java.io.IOException;

class RobotApp {

    public static void main(String[] args) throws IOException {
        
        Runtime.getRuntime().exec(
            new String[] { "chromium-browser", "http://google.com/" }
        );

        Runtime.getRuntime().exec(
            new String[] { 
                "google-chrome", 
                "https://www.google.com/search?q=java+runtime+open+app" 
            }
        );
    }
}

SHELL

Open the terminal and run a command. 
 
/**
 * Usage of Runtime.exec() is discourage (oracle docs)
 * Use ProcessBuilder insteed
 */
import java.io.IOException;

class ExecTest {

    public static void main(String[] args) throws IOException {

        new ProcessBuilder(new String[] {
            "/bin/sh", "-c", 
            "gnome-terminal --command=\"bash -c 'java -version; $SHELL'\""
        }).start();

    }
}
Open the terminal and run jar archive. 
 
import java.io.IOException;

class ExecTest {

    public static void main(String[] args) throws IOException {

        new ProcessBuilder(new String[] {
            "/bin/sh", "-c", 
            "gnome-terminal --command=\"" + 
                "bash -c " +
                    "'cd /var/www/java/projects/Maven/test/ && " +
                    "java -jar test.jar; $SHELL'\""
        }).start();

    }
}
Run shell command in background from java program. 
 
import java.io.IOException;

class ExecTest {

    public static void main(String[] args) throws IOException {

        new ProcessBuilder(new String[] {
            "/bin/sh", "-c",
            "cd /var/www/java/projects/Maven/test/ && " +
                "java -Dname=myapp -jar test.jar"
        }).start();

        // pkill -9 -f myapp 
    }
}

BACKGROUND

The & symbol runs the program in background. The nohup runs the program even if you close the terminal. 
 
#!/bin/sh
nohup java -jar /web/server.jar &
Show all java processes. 
 
ps aux | grep java

    # a = show processes for all users
    # u = display the process's user/owner
    # x = also show processes not attached to a terminal
Use kill if you want to stop a process. 
 
pkill -9 java 
    # kill all java processes

kill -9 PID
    # kill process by id

pkill -9 -f myapp
    # kill process by app name




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