Structure of UNIX system:
The UNIX operating system (OS) consists of a kernel layer, a shell layer and a utilities and applications layer. These three layers create a portable, multiuser, multitasking operating system. There are multiple versions of the OS, but every version has the exact same structure. UNIX is used by programmers, businesses, universities and governments because of its stability and its ability to perform many tasks simultaneously
The UNIX operating system supports the following features and capabilities:
i) Multitasking and multiuser.
ii) Programming interface.
iii) Use of files as abstractions of devices and other objects.
iv) Built-in networking (TCP/IP is standard).
v) Persistent system service processes called “daemons” and managed by init or inet.