Operating Systems Projects

Overview

This repository contains three major projects from CIS 415: Operating Systems, where I developed hands-on experience with systems programming, process scheduling, multithreading, and synchronization in C. Each project progressively built on core OS concepts such as system calls, process management, signals, and thread synchronization.

Projects 📂

Project 1 – Pseudo-Shell (Unix Command-Line Interface)

📌 Description:
Developed a simplified Unix shell, capable of executing basic file and directory manipulation commands. The shell supports both interactive mode (user enters commands via CLI) and file mode (batch execution from a script).

🔹 Key Features:
✅ Implements Unix commands using system calls (e.g., fork(), exec(), open(), read(), write())
✅ Supports file mode execution for batch processing
✅ Includes error handling for invalid commands and parameters
✅ Uses dynamic memory allocation (malloc, free) to prevent memory leaks
✅ Validated with Valgrind to ensure correct memory management

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Project 2 – MCP: Ghost-in-the-Shell (Process Scheduling & Signal Handling)

📌 Description:
Implemented a Master Control Program (MCP) that launches and manages multiple processes using system calls (fork(), exec(), wait(), kill()). The MCP schedules processes in a round-robin fashion and synchronizes execution using signals.

🔹 Key Features:
✅ Uses fork() and execvp() to launch processes from a workload file
✅ Implements signal handling (SIGSTOP, SIGCONT, SIGUSR1) for process scheduling
✅ Uses alarm signals (SIGALRM) to enforce time slices for scheduling
✅ Introduces resource monitoring via /proc for system insights

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Project 3 – Duck Bank (Multithreading & Synchronization)

📌 Description:
Developed a multi-threaded banking system that processes thousands of transactions concurrently while maintaining thread safety using mutexes and condition variables. Transactions include deposits, withdrawals, and fund transfers, with periodic balance updates using thread coordination.

🔹 Key Features:
✅ Uses POSIX threads (pthreads) for concurrent transaction processing
✅ Implements mutexes (pthread_mutex_lock) to prevent race conditions
✅ Coordinates worker threads and a bank thread using condition variables
✅ Uses barriers (pthread_barrier_wait) for synchronized balance updates
✅ Implements inter-process communication (IPC) via mmap() for a secondary bank process

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Lessons Learned 💡

• Project 1: Reinforced system calls, process creation, and file I/O in C.
• Project 2: Gained experience in process scheduling and signal handling.
• Project 3: Developed strong skills in thread synchronization and shared memory management.

Author ✨

👨‍💻 Nikhar Ramlakhan
📚 CIS 415 - Operating Systems | University of Oregon
📝 Instructor: Prof. Allen Malony

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License

This repository contains coursework projects and is intended for educational purposes only.