UNIX is a multiuser, multitasking operating system widely used in servers, workstations, and academic environments for practical computing tasks. In practical use, UNIX provides a command-line interface called the shell, which allows users to interact directly with the system by typing commands. After logging in, the user is presented with a prompt where commands can be executed to manage files, processes, and system resources efficiently. File and directory management is a core practical aspect of UNIX. Commands such as `pwd` are used to display the present working directory, while `ls` lists the contents of a directory. Directories can be created using `mkdir` and removed using `rmdir`. Files are created or viewed using commands like `touch`, `cat`, `more`, and `less`. Copying, moving, and deleting files is done using `cp`, `mv`,