ORGANIZATION OF UNIX

The UNIX system is functionally organized at three levels and are:

1. The kernel, which schedules tasks and manages storage;

2. The shell, which connects and interprets users' commands, calls programs from memory, and executes them; and

3. The tools and applications that offer additional functionality to the OS

The kernel is the heart of the system, a collection of programs written in C that directly communicate with the hardware. There is only one kernel for any system. It's that part of UNIX system that is loaded into memory when the system is booted. It manages the system resources, allocates time between user and processes, decides process priorities, and performs all other tasks. The kernel, in traditional parlance, is often called the Operating system.

The shell, on the other hand, is the "sleeping beauty" of UNIX. It is actually the interface between the user and the kernel. The shell is the agency which takes care of the features of redirection and has a programming capability of its own.

The Tools and Applications consist of Application Software, Compilers, Database Package, Internet tools, UNIX commands, etc.