ABSTRACT
This chapter focuses on the operating system (OS) concepts, digital signatures and scripting fundamentals. The knowledge of the OS is very fundamental and is the backbone of the entire learning. The chapter is drafted with Linux/Unix architecture as a reference. Linux/Unix is one of the most preferred operating systems for almost all industry and enterprise applications. The preference is given to Linux/Unix over Windows. A generalised file system provides a unified and straightforward way to access resources. A directory is a file that may contain other files inside the file. A symbolic link is an empty file that points to a file. The root filesystem contents must be adequate to boot, restore, recover, and/or repair the system. Shell is a program that provides a command-line interface to the OS. So, it can be very well called a command-line interpreter. When programming is used in Shell, it will provide a programming interface to the OS.
