Our Linux ShortCourse has been made available to all site visitors free of charge. The course introduces the Linux operating system to new programmers. Detailed instructions for installing CentOS 7, a widely-used Linux distribution, on a VirtualBox are included in the course. There is also a brief introduction to the Linux file system and to some basic commands used in the command terminal. The information contained in the course is used as a gateway to our other services. I hope site visitors will find it useful.