Monday, February 8, 2016

LINUX-The open source OS

What is 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. The processor performs the instructed task, then sends the results back to the application via the operating system.


The Birth of linux

The Birth of Linux

On August 25, 1991, a Finn computer science student named Linus Torvalds made the following announcement to the Usenet group comp.os.minux:

"I'm doing a (free) operating system (just a hobby, won't be big and professional like gnu) for 386(486) AT clones. This has been brewing since april, and is starting to get ready. I'd like any feedback on things people like/dislike in minix, as my OS resembles it somewhat (same physical layout of the file-system (due to practical reasons) (among other things)."

The “Minix” Torvalds referred to is a variant of the UNIX operating system, used as a guideline for his the free operating system he wanted to run on the x86-based consumer PCs of the day. “gnu” refers to the set of GNU (GNU Is Not Unix) tools first put together by Richard Stallman in 1983. UNIX, the operating system that started it all, had its origins in the old Bell Labs back in the early 60s. Torvalds built the core of the Linux operating system, known as the kernel. A kernel alone does not make an operating system, but Stallman's GNU tools were from a project to create an operating system as well--a project that was missing a kernel to make Stallman's operating system complete. Torvalds' matching of GNU tools with the Linux kernel marked the beginning of the Linux operating system as it is known today.

Linux is in many ways still only at the beginning of its potential, even though it has enjoyed tremendous success since Torvalds' first request for help in 1991. Linux has gained strong popularity amongst UNIX developers, who like it for its portability to many platforms, its similarity to UNIX, and its free software license. Around the turn of the century, several commercial developers began to distribute Linux, including VA Linux, TurboLinux, Mandrakelinux, Red Hat, and SuSE GMbH. IBM's 2000 decision to invest $2 billion in Linux development and sales was a significant positive event to the growth of Linux.

Today, Linux is a multi-billion dollar industry, with companies and governments around the world taking advantage of the operating system's security and flexibility. Thousands of companies use Linux for day-to-day use, attracted by the lower licensing and support costs. Governments around the world are deploying Linux to save money and time, with some governments commissioning their own versions of Linux. The analyst group IDC has projected Linux will be a $49 billion business by 2011, and there are many indications in the market that this figure will be achieved.

How does Linus differ form other OSes?

In many ways Linux is similar to other operating systems you may have used before, such as Windows, OS X, or iOS. Like other operating systems, Linux has a graphical interface, and types of software you are accustomed to using on other operating systems, such as word processing applications, have Linux equivalents. In many cases, the software’s creator may have made a Linux version of the same program you use on other systems. If you can use a computer or other electronic device, you can use Linux.

But Linux also is different from other operating systems in many important ways. First, and perhaps most importantly, Linux is open source software. The code used to create Linux is free and available to the public to view, edit, and—for users with the appropriate skills—to contribute to.

Linux is also different in that, although the core pieces of the Linux operating system are generally common, there are many distributions of Linux, which include different software options. This means that Linux is incredibly customizable, because not just applications, such as word processors and web browsers, can be swapped out. Linux users also can choose core components, such as which system displays graphics, and other user-interface components.

Linux vs Unix?

You may have heard of Unix, which is an operating system developed in the 1970s at Bell Labs by Ken Thompson, Dennis Ritchie, and others. Unix and Linux are similar in many ways, and in fact, Linux was originally created to be similar to Unix. Both have similar tools for interfacing with the systems, programming tools, filesystem layouts, and other key components. However, Unix is not free. Over the years, a number of different operating systems have been created that attempted to be “unix-like” or “unix-compatible,” but Linux has been the most successful, far surpassing its predecessors in popularity.

The Kernel

All operating systems have kernels, built around the architectural metaphor that there must be a central set of instructions to direct device hardware, surrounded by various modular layers of functionality. The Linux kernel is unique and flexible because it is also modular in nature. The kernel of the Window operating system (which few people outside of Microsoft are allowed to look at without paying for the privilege) is a solidly connected piece of code, unable to be easily broken up into pieces. It is difficult (if not impossible) to pare down the Windows kernel to fit on a phone.

This modularity is significant to the success of Linux. The ability to scale down (or up) to meet the needs of a specific platform is a big advantage over other operating systems constrained to just a few possible platforms. Modularity also effects stability and security as well. If one piece of the kernel code happens to fail, the rest of the kernel will not crash. Similarly, an illicit attack on one part of the kernel (or the rest of the operating system) might hamper that part of the code, but should not compromise the security of the whole device.

Who uses Linux?

You’re probably already using Linux, whether you know it or not. Depending on which user survey you look at, between one- and two-thirds of the webpages on the Internet are generated by servers running Linux. Companies and individuals choose Linux for their servers because it is secure, and you can receive excellent support from a large community of users, in addition to companies like Canonical, SUSE, and Red Hat, which offer commercial support.

Many of the devices you own probably, such as Android phones, digital storage devices, personal video recorders, cameras, wearables, and more, also run Linux. Even your car has Linux running under the hood.

Who “owns” Linux?

By virtue of its open source licensing, Linux is freely available to anyone. However, the trademark on the name “Linux” rests with its creator, Linus Torvalds. The source code for Linux is under copyright by its many individual authors, and licensed under the GPLv2 license. Because Linux has such a large number of contributors from across multiple decades of development, contacting each individual author and getting them to agree to a new license is virtually impossible, so that Linux remaining licensed under the GPLv2 in perpetuity is all but assured.

Where is Linux?

One of the most noted properties of Linux is where it can be used. Windows and OS X are predominantly found on personal computing devices such as desktop and laptop computers. Other operating systems, such as Symbian, are found on small devices such as phones and PDAs, while mainframes and supercomputers found in major academic and corporate labs use specialized operating systems such as AS/400 and the Cray OS.

Linux, which began its existence as a server OS and Has become useful as a desktop OS, can also be used on all of these devices. “From wristwatches to supercomputers,” is the popular description of Linux' capabilities.

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