Chapter 19: Networks and Distributed Systems: Structure, Communication, and DFS

Networks and Distributed Systems: Structure, Communication, and DFS begins with a brief history of Linux, tracing its origins from UNIX and its evolution through community-driven, open-source development. The chapter describes the modular kernel architecture, explaining how loadable kernel modules enhance flexibility and maintainability. Process management in Linux is explored through concepts like task structures, scheduling policies (Completely Fair Scheduler), and context switching. Memory management topics include demand paging, the virtual memory system, and the use of page caches. The file system section introduces the Virtual File System (VFS) layer, ext4 and other supported file systems, journaling, and directory management. Linux’s I/O subsystem, including device drivers, block and character devices, and the role of the /proc and /sys virtual file systems, is explained in depth. The chapter also covers interprocess communication mechanisms—pipes, message queues, shared memory, and semaphores—as well as networking features such as sockets and TCP/IP stack integration. Security in Linux is discussed through user/group permissions, capabilities, and security modules like SELinux and AppArmor. By the end, readers understand how Linux’s modular, open-source design enables scalability, portability, and adaptability across everything from embedded devices to supercomputers.