Is linux OS uses unix as it's kernel?

Question

if not pls tell me what the difference between unix and linux is? I know that there are many linux distributions like Ubuntu,Fedora,Knoppix etc.Do all these flavoures use same linux kernel?

Answer 1

Okay, here's a short version:

The term UNIX refers to any operating system based on a certain codebase; visit http://www.unix.org/what_is_unix.html to get some information on the specifics (but it's an incomplete history; search for "what is UNIX" for more info.)

However, most people who say "UNIX" are really referring to any number of operating systems that look like, and work similarly to, UNIX: FreeBSD and GNU/Linux are just a few of these. All use different code, and are developed and maintained (and owned, where ownership applies) by different people or organizations. They don't necessarily run the same software (although they can in many cases) but they work in very similar fashion from a user perspective.

Notice that I said "GNU/Linux" rather than just "Linux"; that's because the actual name of the operating system most people refer to as "Linux" is "GNU/Linux". GNU/Linux is a collection of free software tools (GNU applications) compiled to run on the Linux kernel.

Hopefully that clears up your misconception: Linux is actually a software kernel, and GNU/Linux (commonly referred to as Linux) is the collection of software compiled for and packaged with the LInux kernel that you can find distributed (hence "Linux Distributions") as Ubuntu, Knoppix, etc.

Your quesion "do all these flavors use [the] same linux kernel" is a good question, because they do and they don't. On the one hand, each distribution -- and each version of each distribution, and in many cases each user's installation of each distribution -- may use a kernel that is based on a different version of the kernel source code, and may have been complied with different options. So you can't necessarily take a kernel from one system and drop it on to another; the applications and config files for distribution foo might require a kernel compiled with certain source code and options that a kernel from distribution bar won't have.

However, at the end of the day, all Linux distributions are using one version or another of the Linux kernel codebase; that's what makes them Linux. If you collected the same applications and compiled and ran them on a BSD kernel, you'd be running BSD; compile and run 'em on Darwin and you're running Darwin; and so on. People running all three of those kernels could use the same apps, and have a desktop that looks and works absolutely the same.

So why choose one over the other? Well, different kernels have different numbers of programmers writing drivers and whatnot for them; some are trendier or better known than others; some kernels have stability or (obscure) features that the others lack, or perhaps a distribution you really like uses a particular kernel instead of another. As a user, you shouldn't really care (unless you have a preference between GPL, BSD and other code licenses, which you probably don't at this stage); you should just use the kernel that comes with whatever UNIX-style distribution you like, and which has drivers supporting all of your hardware.

Answer 2

Linux is based on Unix, but its kernel is its own. All Linux distributions use (usually customized) versions of the Linux kernel. There are differences between Unix and Linux, but they depend upon what distribution you're referring to. A Unix user should feel right at home in Linux, however.

Best of all, Linux is open-source.

Answer 3

Linux is the Kernel. GNU which is the top layer of Linux which everyone uses to interface with Linux was developed to match Unix.

All the flavours essentially use the same kernel.