LINUX ADMINISTRATION

INTRODUCTION TO LINUX

Linux was originally developed as a free operating system for Intel x86-based personal computers. It has since been ported to more computer hardware platforms than any other operating system. It is a leading operating system on servers and other big iron systems such as mainframe computers and supercomputers.As of June 2013, more than 95% of the world's 500 fastest supercomputers run some variant of Linux, including all the 44 fastest. Linux also runs on embedded systems, which are devices whose operating system is typically built into the firmware and is highly tailored to the system; this includes mobile phones,tablet computers, network routers, facility automation controls, televisions[and video  game consoles. Android, a widely used operating system for mobile devices, is built on top of the Linux kernel.

Linux  is a Unix-like and mostly POSIX-compliant computer operating system assembled under the model of free and open-source software development and distribution. The defining component of Linux is the Linux kernel, an operating system kernel first released on 5 October 1991 by Linus Torvalds.
The Unix operating system was conceived and implemented in 1969 at AT&T's Bell Laboratories in the United States by Ken Thompson, Dennis Ritchie, Douglas McIlroy, and Joe Ossanna. It was first released in 1971, initially written entirely in assembly language as a common practice at the time. Later, in a key pioneering approach in 1973, Unix was re-written in the programming language C by Dennis Ritchie (with exceptions to the kernel and I/O). The availability of an operating system written in a high-level language allowed easier portability to different computer platforms.

With AT&T being required to license the operating system's source code to anyone who asked (due to an earlier antitrust case forbidding them from entering the computer business), Unix grew quickly and became widely adopted by academic institutions and businesses. In 1984, AT&T divested itself of Bell Labs. Free of the legal obligation requiring free licensing, Bell Labs began selling Unix as a proprietary product.