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difference between linux and unix

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November 2, 2006 11:21:09 PM

What exactly is the difference between unix and linux? Are they related at all?

More about : difference linux unix

a b 5 Linux
November 3, 2006 12:20:26 PM

Basically, at this point, "unix" is used to refer to a type of OS (it technically still has active lineage from the SCO group in the various BSD sources), while Linux is a specific (new from the ground up) implementation of a unix-like system. As such, there are many "unixes", "unices"... whatever, like HP-UX, AIX, IRIX, Linux, and even (some consider) Mac OSX. And the really technical answer is that Linux is just the kernel (main part of OS plus drivers) and GNU/Linux is the kernel plus the useful OS tools, but the people who push this answer need to just relax and stop worrying about semantics.

Think of it this way: unix is like so-called crusing motorcycles (i.e. similar attributes, similar look, similar operation), Linux is like, say, Harleys (or, again, for the truly fastidious, Linux is the standard 88 or now 96 cubic inch v-twin motor with frame and transmission, GNU is the rest of the bike) since they share many of the same parts but there are many, many different overall styles (otherwise known as distributions).

I hope this explanation clears things up a bit.
a b 5 Linux
November 10, 2006 2:13:30 PM

In practice, there really is no difference. The same programs are available and will run on both a Linux and the various UNIX machines (BSD, Solaris, AIX, IRIX, etc.) They both have a similar file structure, similar commands, and the like. There are some very minute differences between how some things are implemented, but for the most part, you can interchange the two and you'd never know the difference. Perhaps the biggest user-visible differences in Linux and UNIX are that drivers, such as ATi or NVIDIA display drivers are not interchangeable between Linux and UNIX. Also, Linux is GPL v2 code and the licenses in UNIX range from the BSD license to proprietary licenses.

In principle, Linux and UNIX are their OSes' kernel- the backest of back-end part of the OS that takes system requests and talks to drivers. The Linux and UNIX kernels are of a little different structure and are not related in structure, but accomplish the same function. Richard Stallman and his GNU group wrote the rest of the backend for most UNIX-like OSes. The GNU system tools are slightly tweaked between UNIX and Linux to deal with each individual kernel but provide the same interfaces on the front end to the programs and such- that is why UNIX and Linux seem so similar.
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December 17, 2006 12:44:26 AM

UNIX is a method of organizing the routing and storage of data signals through and within an assembly of system hardware by way of identifying everything involved, the hardware, the programs, and the data blocks or streams, as "files". At the center of this "file system" sits the "UNIX Kernel" through which these signals travel from "file" (hardware item or software program) to "file" (software program or hardware item). Over the years many UNIX Kernels have been developed, but Linux has emerged as the most successful and useful by far. The Linux Kernel was developed out of the Minix Kernel which was developed from the BSD Kernel which was developed from UNIX System III way back when UNIX was an AT&T product and AT&T was under tight antitrust regulations. Only later did AT&T develop UNIX System V and later still System V Rev. 4, some right to which they licenced to the SCO company. In 2000 the Caldera company, itself a Linux distributor, bought the SCO company; in 2002 Caldera officially changed its name to SCO; and in 2003 this Linux distribution company which then called itself "SCO" began to threaten Linux users (among whom were its own clients) with lawsuits. Got it?
a b 5 Linux
December 17, 2006 9:03:37 AM

About the only good thing SCO did to the UNIX source was to help remove MS copyright claims to some of the Xenix components. But then the irony is that at the time MS owned a 20% investment in SCO. Vr4 Licences were making MS cash.
February 18, 2009 10:52:02 PM

The way I've always read and heard is that Linux is the Windows of Unix. Like how Windows is Dos based and always has Dos in the background, Linux is Unix based and always has Unix in the background.
a b 5 Linux
February 18, 2009 11:22:37 PM

Thanks for posting :)  but it looks like the forum software dug up another ancient post from three years ago. Oops.

Linux is not descended from Unix, it is a complete re-write.

Quote:
http://kernel.org Linux is a clone of the operating system Unix, written from scratch by Linus Torvalds with assistance from a loosely-knit team of hackers across the Net. It aims towards POSIX and Single UNIX Specification compliance.


Linux is also free and open source.

:) 
a b 5 Linux
February 19, 2009 7:24:02 AM

Note that there are a couple of free, open-source, genuine Unixes available - BSD and OpenSolaris.
a b 5 Linux
February 19, 2009 7:35:44 AM

Linux is like a hobbyist Unix. All Linux distros share the same core kernel. Linux was made in the image whilst windows was made in the image of DOS.
a b 5 Linux
February 21, 2009 5:47:24 PM

Ijack - Is Solaris really Unix? I can't see that SCO would allow an unlicensed Unix implementation.
a b 5 Linux
February 21, 2009 9:05:31 PM

Solaris is really Unix and complies with the Single UNIX Specification.

:) 
February 22, 2009 1:28:14 AM

Unix can also be MacOS X, AIX (IBM's Unix) and HP-UX (HP's Unix).

Anyways, Unix and Linux has many similarities and some differences. For example, most commands used on a Linux system can be used on a Unix (Solaris, BSD, Mac OS X) with little or no variation in switches and behavior. Unix and Linux have similar design, and their kernel use the same general idea, though with each Unix/Linux variation, it has its differences. However, Unix was engineered in the late 60s, ran on large computers and wasn't really what it is today. Although the newest Unix systems (OS X, Solaris and Unix variants [Linux]) use some of the same concepts that were in use in the late 60s, it wasn't until BSD and System 7 (AT&T) when Unix began to be engineered the way we see it today. And that's not to say that Unix isn't being added on, although not much.

There is something called POSIX compliant, which is a set of standards (POSIX is Portable Operating System Interface) - Unix was the root of POSIX. However, Windows NT (NT, 2000, XP, Server, Vista, 7) is somewhat POSIX compliant. Linux, surprisingly, is only somewhat compliant, simply because there are too many variations of it, but Solaris, BSD and OS X are fully POSIX compliant. However, just because it is POSIX compliant doesn't mean its Unix. (Ha! Windows Vista, for example, is FAR from it!)

The advantages of Unix and Linux is that it is very robust, secure and trusted for heavy duty tasks. You wouldn't use Windows XP, for example, to run a nuclear power plant or keep billing information for a large cell-phone provider company. You'd use Unix or a variant of it. Unix and Linux are inherently secure in their design, and most Unix variants have features to help keep it that way. Unix and Linux are also very versatile--you could put Unix to use for tasks as big as a Net server of a popular site all the way to a desktop business computer, and, since some Linux distros are easy to use, such as Ubuntu, it could also be used in schools and homes.

Right now, Windows is the only non-Unix operating system in wide use (note I said wide use--I know there's Non-Unix, Non-Microsoft OSes out there, but who uses them but a select few?). I'm sure down the road that the NT kernel will over stay its welcome at Redmond and find itself in the digital Dumpster behind their headquarters :p  and that Microsoft will adapt a Unix kernel much like Apple did with Mac OS X. Everything else (that's widely in use) runs Unix or a variant. So once Microsoft makes that change and only if they decide to, then the world will be 99% Unix or Unix-variant.
a b 5 Linux
February 22, 2009 3:04:40 AM

Linux-FT is officially POSIX.1 (FIPS 151-2) certified.

Other Linux distributions are very POSIX'ish but not officially certified.

:) 
February 22, 2009 4:14:06 AM

Does anyone else find it ironic that apple switched its operating system to be unix-based? They aren't exactly "thinking differently" by moving back towards a system that has been a long established standard in OS design. It was probably a smart move on their part, but that doesn't mean it isn't hypocritical ;) 

--Zorak

P.S. As I have become interested in different operating systems, I think it would be cool if we saw other non-MS, non-Unix-derivative OSes become more prominent. I'd kind of like to try out SkyOS, MenuetOS/KolibriOS, Haiku/BeOS, and AmigaOS just to see what kind of different ideas are available. Maybe if I ever have free time ever again (probably not anytime this semester), I might eventually give them a whirl.

a b 5 Linux
February 22, 2009 8:24:19 AM

concorde said:
Right now, Windows is the only non-Unix operating system in wide use (note I said wide use--I know there's Non-Unix, Non-Microsoft OSes out there, but who uses them but a select few?). I'm sure down the road that the NT kernel will over stay its welcome at Redmond and find itself in the digital Dumpster behind their headquarters :p  and that Microsoft will adapt a Unix kernel much like Apple did with Mac OS X. Everything else (that's widely in use) runs Unix or a variant. So once Microsoft makes that change and only if they decide to, then the world will be 99% Unix or Unix-variant.



The NT kernel is actually based on the VMS model, WNT being one better than VMS. Think about that one, the same guy wrote both. As for POSIX I've run code written for VMS on NT before now through the POSIX shell along with a few Unix tape utilities. Really the fact that POSIX exists shows how ANSI C type standards failed to actually achieve true portability.

It very much depends on what you call wide use. Everybody in my company uses OS390 in their daily jobs but we only have one (very big!) machine running it. Hardly a large install base but very heavy use. Also don't forget the number of VMS installations out there, I've worked on a few sites where VMS is still running the business, again this is frequently abstracted from the end users. Unix is good, but not without flaws. I'm waiting to see what the Hurd can do once it reaches a reasonable degree of maturity.
a b 5 Linux
February 22, 2009 9:09:20 AM

audiovoodoo said:
Ijack - Is Solaris really Unix? I can't see that SCO would allow an unlicensed Unix implementation.

SCO have nothing to do with it (nothing to do with much nowadays!). It's been established in court that Novell, not SCO, holds the rights to Unix.
February 23, 2009 12:25:47 PM

BeOS is Unix based. It's really not widely used anymore - Windows, Mac OS and Linux (and then for Unix: Sun Solaris) are the most widely used OSes today - BeOS is a thing of the past.

Solaris is really Unix. In fact, it is one of the most popular commercial Unix out there beside Mac OS.
a b 5 Linux
February 23, 2009 2:41:22 PM

Quote:
BeOS is Unix based.
That's an interesting statement. Although many GNU programs were ported to BeOS I've never heard anyone suggest that it is based on Unix. It's not even a multi-user OS.

Mac OS is not Unix, any more than Linux is.
a b 5 Linux
February 23, 2009 8:05:53 PM

Mac OS 10.5 is certified UNIX 03 under the Single UNIX Specification.

Linux is a Unix clone.

:) 
a b 5 Linux
February 23, 2009 8:15:00 PM

You're quite correct BeOS is not Unix, officially or otherwise.

:) 
a b 5 Linux
February 24, 2009 7:04:27 AM

linux_0 said:
Mac OS 10.5 is certified UNIX 03 under the Single UNIX Specification.
I stand corrected.

I was being a little pedantic and referring to the derivation of the kernel, rather than what standards it complies with. The OS X kernel, like the Linux kernel, was not derived from any Unix source code; the various BSD kernels and the Solaris one were.

February 24, 2009 4:39:32 PM

Zorak said:
Does anyone else find it ironic that apple switched its operating system to be unix-based?


Does the word 'NeXT' mean anything to you?

Steve Jobs has been doing Unix (or, at least, Unix-like OSes) for twenty years.
February 24, 2009 5:56:50 PM

Yes I know about NeXT, and I am aware of the competition they had with Be Inc to position themselves as the next incarnation of the Mac. Just because you thought i didn't know about jobs' efforts while he was no longer at apple does NOT make my observation any less valid. As I recall, the "think differently" campaign came out about the time has OSX first came out, which means it was after jobs rejoined apple. Seeing as how jobs rules apple with an iron fist, he would have had to approve that campaign slogan, which only further serves to underscore my point: They were fully aware that they had moved away from an orignal OS towards a more standard OS design, and yet they claim to be doing something completely "different" and innovative.

-Zorak




Edit: fixed a minor grammatical error.
a b 5 Linux
February 28, 2009 9:56:33 AM

If you want to play with a NeXT environment then take a look atOpen Step. You can take a bit of a look at it running on Mach here



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