LINUX FOUNDATION

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.

Explained in these terms, Linux is very similar to other operating systems, such as Windows and OS X.

But something sets Linux apart from these operating systems. The Linux operating system represented a $25 billion ecosystem in 2008. Since its inception in 1991, Linux has grown to become a force in computing, powering everything from the New York Stock Exchange to mobile phones to supercomputers to consumer devices.

As an open operating system, Linux is developed collaboratively, meaning no one company is solely responsible for its development or ongoing support. Companies participating in the Linux economy share research and development costs with their partners and competitors. This spreading of development burden amongst individuals and companies has resulted in a large and efficient ecosystem and unheralded software innovation.

Over 1,000 developers, from at least 100 different companies, contribute to every kernel release. In the past two years alone, over 3,200 developers from 200 companies have contributed to the kernel--which is just one small piece of a Linux distribution.

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.

The Future of Linux

Linux is already successful on many different kinds of devices, but there are also many technological areas where Linux is moving towards, even as desktop and server development continues to grow faster than any other operating system today.

Linux is being installed on the system BIOS of laptop and notebook computers, which will enable users to turn their devices on in a matter of seconds, bringing up a streamlined Linux environment. This environment will have Internet connectivity tools such as a web browser and an e-mail client, allowing users to work on the Internet without having to boot all the way into their device's primary operating system--even if that operating system is Windows.

At the same time, Linux is showing up on mobile Internet devices (MIDs). This includes embedded devices such as smartphones and PDAs, as well as netbook devices--small laptop-type machines that feature the core functionality of their larger counterparts in a smaller, more energy-efficient package.

As new web services arrive in the future, Linux will increasingly be the platform that drives these new technologies.

The Birth of Linux

Linus Torvald On August 25, 1991 came up with Linux.

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. 

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.

The Code

Linux is also unique from other operating systems in that it has no single owner. Torvalds still manages the development of the Linux kernel, but commercial and private developers contribute other software to make the whole Linux operating system.

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 is a solidly connected piece of code, unable to be easily broken up into pieces. It is difficult  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. 

The Operating System

Developers need special tools (like the compilers and command lines found in GNU) to write applications that can talk to the kernel. They also need tools and applications to make it easy for outside applications to access the kernel after the application is written and installed.

This collective set of tools, combined with a kernel, is known as the operating system. It is generally the lowest layer of the computer's software that is accessible by the average user. General users get to the operating system when they access the command line.

Linux provides powerful tools with which to write their applications: developer environments, editors, and compilers are designed to take a developer's code and convert it to something that can access the kernel and get tasks done.

Like the kernel, the Linux operating system is also modular. Developers can pick and choose the operating tools to provide users and developers with a new flavor of Linux designed to meet specific tasks.

The Environments

The windows, menus, and dialog boxes most people think of as part of the operating system are actually separate layers, known as the windowing system and the desktop environment.

These layers provide the human-oriented graphical user interface (GUI) that enables users to easily work with applications in the operating system and third-party applications to be installed on the operating system.

In Linux, there a lot of choices for which windowing system and desktop environment can be used, something that Linux allows users to decide. This cannot be done in Windows and it's difficult to do in OS X.

Like the operating system and kernel, there are tools and code libraries available that let application developers to more readily work with these environments (e.g., gtk+ for GNOME, Qt for KDE).

The Applications

Operating systems have two kinds of applications: those that are essential components of the operating system itself, and those that users will install later. Closed operating systems, like Windows and OS X, will not let users (or developers) pick and choose the essential component applications they can use. Windows developers must use Microsoft's compiler, windowing system, and so on.

Linux application developers have a larger set of choices to develop their application. This allows more flexibility to build an application, but it does mean a developer will need to decide which Linux components to use.

Community

Linux communities come in two basic forms: developer and user communities.

One of the most compelling features of Linux is that it is accessible to developers; anybody with the requisite skills can improve Linux and influence the direction of its development. 

Developer communities can volunteer to maintain and support whole distributions, such as the Debian or Gentoo Projects. Novell and Red hat also support community-driven versions of their products, openSUSE and Fedora, respectively. The improvements to these community distros are then incorporated into the commercial server and desktop products from these companies.

The Linux kernel itself is primarily supported by its developer community as well and is one of the largest and most active free software projects in existence. A typical three-month kernel development cycle can involve over 1000 developers working for more than 100 different companies (or for no company at all).

With the growth of Linux has come an increase in the number of developers (and companies) wishing to participate in its development. 

Other developer communities focus on different applications and environments that run on Linux, such as Firefox, OpenOffice.org, GNOME, and KDE.

End users, too, can make valuable contributions to the development of Linux. With online communities such as Linux.com, LinuxQuestions, and the many and varied communities hosted by distributions and applications, the Linux user base is an often vocal, usually positive advocate and guide for the Linux operating system.

Development

Linux is an operating system that is comprised of many different development languages. A very large percentage of the distributions' code is written in either the C (52.86%) or C++ (25.56%) languages. All of the rest of the code falls into single-digit percentages, with Java, Perl, and Lisp rounding out the rest of the top 5 languages.

The Linux kernel itself has an even more dominant C presence, with over 95 percent of the kernel's code written in that language. But other languages make up the kernel as well, making it more heterogenous than other operating systems.

The kernel community has evolved its own distinct ways of operating which allow it to function smoothly (and produce a high-quality product) in an environment where thousands of lines of code are being changed every day. This means the Linux kernel development process differs greatly from proprietary development methods.

The kernel's development process may come across as strange and intimidating to new developers, but there are good reasons and solid experience behind it.

While many Linux developers still use text-based tools such as Emacs or Vim to develop their code, Eclipse, Anjuta, and Netbeans all provide more robust integrated development environments for Linux.