What is Unix?
All Unix, Linux and other Unix-like operating systems are families of computer operating systems derived from the original Unix System from Bell Telephone Laboratories. Today, the largest Unix descendent directly certified as "UNIX" is macOS by Apple. The original commercial Unix derivatives included HP-UX, AIX and SunOS, to name a few. The diversity and perceived incompatibility between various Unix systems led to the creation of interoperability standards including the Portable Operating System Interface (POSIX).
Unix is the original and most powerful and popular multi-user and multi-tasking Operating System. The basic concepts of Unix were originated in the Multics project of 1969. The Multics system was intended as a time-sharing system that would allow multiple users to simultaneously access a mainframe computer. Ken Thompson, Dennis Ritchie, and others developed the basic building blocks of Unix including a hierarchical file system and a command line interpreter for the PDP-7. Multiple generations of Unix systems were developed for myriad computers.
As mentioned, historical perceived incompatibility between the various early Unix systems led to the creation of POSIX and the Single Unix Specification. Historically, the rigid "standardization" approach led to the creation of various open source approaches to Unix including the Free Software Foundation (FSF), GNU and Linux. Unix programs were originally created around core design philosophies that included requirements like single purpose, interoperable, and working with a simple standardized text interface. Unix systems are built around a core kernel that manages the system and the other processes. Kernel subsystems may include process management, file management, memory management, network management and others.
- Unix is a multi-user system where the resources can be shared by various system users.
- Unix provides multi-tasking. Users can execute many processes at the same time (practically speaking).
- Unix was the first computer operating system that was written in a high-level language (C Language).
- Unix provides a hierarchical file structure which facilitated fast data access.
- Unix has built-in networking functions so that computers can easily exchange information.
- Unix functionality can be extended through user programs built on a standard programming interface.
- UNIX certifies compliance with a full set of interoperability standard, managed and maintained by the Open Group, which includes, not only the kernel, but the entire operating system.