There are different types of Operating Systems. One of the most important Operating system is Linux Operating system. Most of the industries use Linux Operating System as it is multiuser, multithreaded Operating System. Linux has various flavors like Kali Linux, Ubuntu, etc. Linux works in two modes Graphics User Interface & Command Line Interface. Linux commands are needed many times in industry for various operations. There are thousands of commands in Linux. In this course I will cover frequently used commands. In first section I will tell you about General Purpose commands like date, time, cal, clear, tty, script, man commands. This section also cover basic commands like who, who am i, login, password, su and pwd commands. In second section I will tell you about various Process commands like ps, wait, sleep, exit. In third section I will teach you various file and directory manipulation commands. In first lecture I will cover ls, rm, mv, cp, join, split, cat, head, tail and touch commands. In second lecture I will teach diff, comm, pr, chmod, mkdir, rmdir, cd, pwd, dir and cmp commands. In fourth section I will cover various text processing commands like tr, wc, cut, paste, spell, sort, grep and more command.