This book, designed to meet the course on UNIX and SHELL Programming for graduate and undergraduate engineering students, presents an illuminative and objective exploration of algorithms and programming skills on UNIX and SHELL. The authors discuss all the concepts such as operating system services, file system, buffer cache, reading and writing disk blocks, inode assignment to a new file, system calls, structure and control of a process, inter-process communication, and sockets with the help of illustrations, tables, block diagrams, and industry based practical examples.