The GNU Project, now sponsored by the Free Software Foundation, was founded in 1984 by Richard M. Stallman.

In 1992, a free kernel was developed by Linus Torvalds, a computer science student at the University of Helsinki. The Linux kernel is released under the GNU General Public License, or GPL.

Linux is a free, open source operating system. For the most part, anybody may download and install Linux free of cost.

There are many distros (types, flavors, variations) available. One can use a virtual machine or Live CD to set up a temporary system to use in the course.

Some prominent distros:

• Debian - This is the distro that Knoppix is based on; it is very stable.
• Red Hat - Actually a family of distros, from Red Hat Enterprise Linux (RHEL)
• Slackware - A simple package management system, but very stable.
• Gentoo - A distro that compiles all software from source. 
• Linux From Scratch (LFS) - Not a distro but is a book that tells you how to make your own Linux. 

Command Line Interface (CLI) advantages

• Universal – CLI functions in any Linux environment
• Powerful
• Remote functions

CLI commands

• $  - Command prompt
• $ pwd  - This prints the working directory
• cd  - Change Directory
• . (period)  - Represents the current working directory
• .. (double period)  - Represents the parent directory
• $ ls  - This tells what is in the directory that you are in

Paths represent locations of files. There are absolute paths, given from the root directory, and relative paths, given from the current location.

Man pages are manuals for commands and other important parts of the system.