Linux Operating System
Linux Operating System is one of standard version of UNIX operating System. It is open source because its source code is freely available and it is free to use. Linux was designed considering UNIX compatibility and its functionality is quite comparable to that of UNIX.
Components of Linux System
Linux OS has mainly three components
- Kernel: Kernel is the essential part of Linux. It is accountable for all main activities of this operating system. It is contains various modules and it interacts directly with the fundamental hardware. Kernel delivers the required abstraction to hide low level hardware details to application programs or system.
- System Shared Library: System libraries are exceptional functions or programs using which system utilities or application programs accesses Kernel’s features. These libraries implements most of the functionalities of the operating system and do not involves kernel module’s code access rights.
- System Utility: System Utility programs are accountable to do particular, individual level tasks.
Kernel Mode Vs User Mode
Kernel component-code executes in a exceptional privileged mode called kernel mode with filled access to all resources of the computer. This code characterizes a single process, executes in single address-space and do not want any context switch and therefore it is very efficient and fast. Kernel runs each and every process and delivers system services to processes, offers protected access to hardware to processes. Support-code that is not mandatory to run in kernel mode is in System Library. User programs and other system programs works in user-mode that has no access to system hardware and kernel code. User programs or utilities use System libraries to use kernel-functions to get system’s low level tasks.
There are some of the main features of Linux OS which are given as:
- Portable: Portability means software could works on diverse types of hardware in same Application programs and Linux kernel support their installation on any kind of hardware platform.
- Open Source: Linux source-code is easily, free of cost available and it is community based-development project. Several teams work in association to enhance the proficiency of Linux operating system and it is continuously evolving.
- Multi-User: Linux is a multi-user system means multiple users can access system resources like ram, memory and application programs simultaneously.
- Multiprogramming: It is a multi-programming system that means multiple applications can run simultaneously.
- Hierarchical File System: It delivers a standard file structure in which system files or user files are arranged.
- Shell: Linux offers a special interpreter program that can be used to execute commands of the OS. It can be used to do several types of operations, call application programs and so on.
- Security: It delivers user security by means of authentication features like password protection or controlled access to specific files or encryption of data.
Linux System’s Architecture is consists of given layers:
- Hardware layer: Hardware contains all peripheral devices such as RAM, HDD, CPU and so on.
- Kernel: Fundamental component of Operating System that interacts directly with hardware, delivers low level services to upper layer components.
- Shell: An interface to kernel encapsulating complexity of kernel’s functions from its users. Gets commands from user and then executes kernel’s functions.
- Utilities: Utility programs providing user most of the functionalities of an OS.