Linux

Linux refers to the family of operating systems based on the open-source Linux Kernel [first released in 1991] with a largely Unix-like interface. This family of operating systems is distributed and specialized for varied purposes, such as desktops, smartphones, mainframes, edge computing devices, etc. Linux was solely built as an open-source project and today is the most widely used family of operating systems in the world.

The core competencies include an understanding of desktop and window managers, theoretical fundamentals, and utilizing the networking layer in Linux, inter-process communication, and user management for the administration of a Linux system.

1. Desktop and Window managers - The desktop and window manager together implement components that work together to provide a seamless graphical user interface. 
2. Networking - Linux implements a networking substructure by default. An understanding of core concepts such as DNS, TCP/IP, networking layers, and troubleshooting. Ability to set up a web server or FTP server locally and blacklist a domain.
3. Inter-Process communication - Linux provides interfaces such as message queues, pipes, sockets, and shared files for processes to communicate and synchronize with each other.
4. User management - User management includes everything from creating a user to deleting a user or managing permissions on a Linux system.