Thursday, July 3, 2008

Understanding the Linuxisms

The word Linux has different meanings, depending on the context in which it's referred to:

Linux kernel: Linux is the operating system that controls everything you do on your Ubuntu computer; this is technically the Linux kernel. The Linux kernel controls who can use resources like memory, disk space, and time allocated on the central processing unit (CPU).

Linus Torvalds started writing the Linux kernel in 1991 because he wasn't satisfied with any of the operating systems he had access to. Early on, he released his work to the nascent Internet and immediately hit a nerve. The power of communication and the need for such an operating system resulted in many talented people helping to make the project a success. Linus also licensed his work under the GNU General Public License (GPL), which allowed people to use, modify, and distribute his work as long as they allowed others to do the same. Using the Internet and GPL, Linux quickly exploded into worldwide use and today is second only to Microsoft Windows in use.

Linux distribution: Linux is also the overall system that consists of the Linux kernel and all the supporting systems. Ubuntu Linux is an example of this. Ubuntu is a Linux distribution that contains the Linux kernel, GNU applications, the Linux file system, a graphical environment, and many other subsystems.

Multiuser: Linux is a multiuser operating system. People can share a Linux computer. You assign separate user accounts to each person, which limits one person from interfering with another.

Multitasking: Linux is a multitasking operating system. You can run multiple programs at the same time.

Each program gets a slice of time to perform its task before being forced into the background, so that the next program in line can get its slice. Computers operate so quickly, however, that all processes appear to be running at once.

GNU: GNU is a comprehensive and free operating system project that was started in 1983 by Richard Stallman. It consists of a kernel, system utilities, libraries, compilers, and system administration programs.

GNU is a recursive acronym for GNU's Not UNIX.

The kernel wasn't released until recently, but the other parts have been very widely used for decades. Linux wouldn't be a popular operating system today if not for GNU. Many people reasonably refer to GNU Linux when talking about Linux. That makes sense because Linux, as I just mentioned, originally was just the operating system kernel. When the Linux kernel was released in 1992, it was quickly combined with GNU software to create a usable operating system. However, the powerful forces of popular lexicon, branding, and pure inertia set using the single word Linux into place.

GPL: The GNU General Public License (also referred to as the GNU Public License) was created by Richard Stallman. There are other similar licenses in use, but the GPL is their ancestor. GPL is the reason that Linux, Mozilla Firefox, and many other applications exist today.

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