
\S UNIX:  UNIX operating system:  UNIX system:  operating system: kernel
\S

The UNIX system is a set of programs that include an operating system and a
set of programs which are commands for users.  An operating system is the
program that mediates between the compiler, the CPU, input and output
devices, and data storage devices.  The operating system has two basic
parts:

   1)   The kernel is the program in the UNIX operating system that is
        responsible for most operating system functions.  It schedules
        and manages all the work done by the computer and maintains the
        file system.  It is always running.

   2)   The shell is the UNIX operating system program responsible for
        handling all interaction between users and the computer.  It
        includes a powerful command language called shell language.

The programs or UNIX commands are executed using the shell, and allow users
to do things like communicate with each other, to edit and manipulate
files, and to write and execute programs in several programming languages.

