Unix
It is a a family of operating systems derived from the original Unix system developed by AT&T Bell Labs in the 1970s.
POSIX (Portable Operating System Interface)
It is a standard for Unix operating systems, maintained by IEEE which ensures cross-compatibility between various operating systems.
GNU Project
It is project for developing free software (and operating system). GNU stands for “GNU is Not UNIX”
Linux
It is a free and open source operating system used in all of the top super-computers.
Kernel
It is the interface between software and the hardware. It runs the hardware at low level. Some functionalities include:
- Process scheduling
- Inter-process communication
- Networking
- Memory management
- File handling (virtual file system)
Shell
It is a text based user interface in UNIX/Linux. A “shell” around the kernel