Explanation

1. Purpose

This program demonstrates core operating system process management concepts by showing how a program retrieves its own process IDs, creates a separate child process, and waits for it to complete.

2. Key Concepts

System Calls: Requests made by a program to the operating system kernel (e.g., getting process IDs, creating processes).
PID & PPID: Process ID (unique identifier for a running process) and Parent Process ID (the ID of the process that launched it).
Process Creation & Synchronization: Spawning a new independent process (start()) and pausing the parent until the child finishes (join()).

3. Code Walkthrough

Lines 3–5 (os.getpid(), os.getppid()): Calls OS-level functions to retrieve and display the unique ID of the current process and its parent process (e.g., the terminal or IDE).
Lines 6–7 (child_process()): Defines the function that will execute inside the newly created child process.
Line 9 (p = multiprocessing.Process(...)): Prepares a new child process with child_process as its target task.
Line 10 (p.start()): Issues an OS request (like fork() or spawn) to launch and run the child process concurrently.
Line 11 (p.join()): Pauses execution of the parent process until the child finishes (similar to the wait() system call).
Lines 12–15: Runs after the child completes; the parent prints its own PID alongside the finished child's PID.

4. Sample Output

(Note: Actual PID numbers will vary every time you run the script.)

----- SYSTEM CALL DEMONSTRATION -----
Process ID: 12345
Parent Process ID: 9876

Child Process is executing with PID 12346

Parent Process
Parent PID: 12345 
Child PID: 12346
Child process has completed.

System calls demonstration completed.