LINUX

Linux is an operating system kernel that provides memory management, file system abstraction, basic networking, and other essential services to an operation system.

The fact that the operating system is free of cost and also freely-modifiable adds tremendous value.

Philosophy

  • Do one thing well
  • Simplicity - Simplicity makes systems and code easier to use, extend, modify, and maintain.

Kernel

The operating system must fulfill two main objectives:

  • Interact with the hardware components, servicing all low-level programmable elements included in the hardware platform
  • Provide an execution environment to the applications that run on the computer system (the so-called user programs).

Unix-like operating system hides all low-level details concerning the physical organization of the computer from applications run by the user. When a program wants to use a hardware resource, it must issue a request to the operating system.

This mechanism enforced.

The hardware introduces at least two different execution modes for the CPU: a non-privileged mode for user programs and a privileged mode for the kernel. Unix calls these USER MODE and KERNEL MODE, respectively.

KERNEL is At the heart of the operating system. An intermediary between hardware and software.

References

  • Understanding the LINUX KERNEL / Daniel P.Bovet & Marco Cesati