A comprehensive 4-week study guide for Operating Systems, created by a 3rd-year CS student for campus placements. This guide covers essential OS concepts from process management to Linux commands, focusing on practical interview questions rather than textbook theory. The guide addresses why students often forget 80% of OS material after exams and provides a structured approach to relearning concepts properly.

It includes detailed explanations of process vs thread, CPU scheduling algorithms (FCFS, SJF, SRTF, Round Robin), concurrency problems, memory management, and critical Linux commands. The author emphasizes understanding over memorization, sharing real interview questions and coding examples. Key topics include deadlock prevention, page replacement algorithms, mutex vs semaphore, and practical Linux commands for file permissions, process monitoring, and text processing.

The guide follows a 2-3 hour daily schedule over 4 weeks, making it ideal for placement preparation.