Operating System — Linux
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
- 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 requires kernel module’s code access rights.
- System Utility − System Utility programs are responsible to do specialized, individual level tasks.
Kernel Mode vs User Mode
Kernel component code executes in a special privileged mode called kernel mode with full access to all resources of the computer. This code represents a single process, executes in single address space and do not require any context switch and hence is very efficient and fast. Kernel runs each processes and provides system services to processes, provides protected access to hardware to processes.
Support code which is not required to run in kernel mode is in System Library. User programs and other system programs works in User Mode which has no access to system hardware and kernel code. User programs/ utilities use System libraries to access Kernel functions to get system’s low level tasks.
Basic Features
Following are some of the important features of Linux Operating System.
- Portable − Portability means software can works on different types of hardware in same way. Linux kernel and application programs supports their installation on any kind of hardware platform.
- Open Source − Linux source code is freely available and it is community based development project. Multiple teams work in collaboration to enhance the capability of Linux operating system and it is continuously evolving.
- Multi-User − Linux is a multiuser system means multiple users can access system resources like memory/ ram/ application programs at same time.
- Multiprogramming − Linux is a multiprogramming system means multiple applications can run at same time.
- Hierarchical File System − Linux provides a standard file structure in which system files/ user files are arranged.
- Shell − Linux provides a special interpreter program which can be used to execute commands of the operating system. It can be used to do various types of operations, call application programs. etc.
- Security − Linux provides user security using authentication features like password protection/ controlled access to specific files/ encryption of data.
Architecture
The following illustration shows the architecture of a Linux system −
The architecture of a Linux System consists of the following layers −
- Hardware layer − Hardware consists of all peripheral devices (RAM/ HDD/ CPU etc).
- Kernel − It is the core component of Operating System, interacts directly with hardware, provides low level services to upper layer components.
- 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.
- Utilities − Utility programs that provide the user most of the functionalities of an operating systems.
What is Linux?
Linux® is an open source operating system (OS). An operating system is the software that directly manages a system’s hardware and resources, like CPU, memory, and storage. The OS sits between applications and hardware and makes the connections between all of your software and the physical resources that do the work.
What’s a command line?
The command line is your direct access to a computer. It’s where you ask software to perform hardware actions that point-and-click graphical user interfaces (GUIs) simply can’t ask.
Command lines are available on many operating systems—proprietary or open source. But it’s usually associated with Linux, because both command lines and open source software, together, give users unrestricted access to their computer.
Our latest release of Red Hat® Enterprise Linux comes with even more built-in command line capabilities than ever before and includes consoles that bundle those capabilities in easy-to-use modules that exist off of the command line.
How does Linux work?
Think about an OS like a car engine. An engine can run on its own, but it becomes a functional car when it’s connected with a transmission, axles, and wheels. Without the engine running properly, the rest of the car won’t work.
Linux was designed to be similar to UNIX, but has evolved to run on a wide variety of hardware from phones to supercomputers. Every Linux-based OS involves the Linux kernel—which manages hardware resources—and a set of software packages that make up the rest of the operating system. Organizations can also choose to run their Linux OS on a Linux server.
The OS includes some common core components, like the GNU tools, among others. These tools give the user a way to manage the resources provided by the kernel, install additional software, configure performance and security settings, and more. All of these tools bundled together make up the functional operating system. Because Linux is an open source OS, combinations of software can vary between Linux distributions.
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