Linux- Linux is, in simplest terms, an operating system. It is the software on a computer that enables applications and the computer operator to access the devices on the computer to perform desired functions. The operating system (OS) relays instructions from an application to, for instance, the computer's processor.

Linux is one of popular version of UNIX operating System. It is open source as its source code is freely available. It is free to use. Linux was designed considering UNIX compatibility. Its functionality list is quite similar to that of UNIX.

Components of Linux System

Linux Operating System has primarily three components

• System Utility − System Utility programs are responsible to do specialized, individual level tasks.
• Kernel − Kernel is the core part of Linux. It is responsible for all major activities of this operating system. It consists of various modules and it interacts directly with the underlying hardware. Kernel provides the required abstraction to hide low level hardware details to system or application programs.
• System Library − System libraries are special functions or programs using which application programs or system utilities accesses Kernel's features. These libraries implement most of the functionalities of the operating system and do not require kernel module's code access rights.                                                             

  Architecture

  The following illustration shows the architecture of a Linux system −                                                                                                                                                                      

• Utilities − Utility programs that provide the user most of the functionalities of an operating systems.
• Kernel − It is the core component of Operating System, interacts directly with hardware, provides low level services to upper layer components.
• Hardware layer − Hardware consists of all peripheral devices (RAM/ HDD/ CPU etc.).
• Shell − an interface to kernel, hiding complexity of kernel's functions from users. The shell takes commands from the user and executes kernel's functions.