difference between Linux/Unix
 

This is probably a real newbie question but I am exactly that so I'll ask it anyways.

Can anyone tell me what the heck the difference is between UNIX and Linux. I am failing to figure it out on my own.

Thanks,

Unix is written in an assembly language so it's designed to work with very specific hardware. Another words it's form fit to the system. But Linux is written in C which is very protable and adaptable so it works just about everywhere.

Unix has been written in C since version 6 (the kernel... most of the apps sans assembler by version 7). That's 1973 for the kernel being ported to C... in case you were wondering.

The fact that it was written in C was the reason it took off so much. It would be wrong to say that Unix is written in assembly anymore than Linux is written in assembly. Some chunks are written in assembly but the majority of both operating systems are in C.

Note: Technically Unix is any system which conforms to the standard and has paid for certification saying that and thus has the right to use Unix (which is a registered trademark) in their product name and description.

Unix has several variants and Linux is a copy of a copy of one style. Basically... linux is very close. The differences are going to be as dramatic as the differences between AIX and solaris (which are both Unix trademarked). In short... everything is different and almost nothing is different.

Linux doesn't share any lines of code with unix (at least it had better not or SCO is right) but it does act in a manner similar to any "real" Unix system you would find.

For more information about what it takes to be a "real" Unix... look at the following page. http://www.unix.org/version3/

This is the updated standard all systems must conform to if they want to be Unix 3 compliant. Then they pay (huge megabucks) and get certified that they meet this standard... and they can be called Unix. The old one (Unix 98) is where most commercial Unix products fall today. I don't know if any have got the updated certification.

Many a times we get confused with Unix and Linux also threat them as synonyms but that is not true. UNIX is copyrighted name only few of the companies are allowed it i.e. IBM AIX and Sun Solaris and HP-UX. This quote from Official Linux kernel README file confuses most:

Linux is a Unix clone written from scratch by Linus Torvalds with assistance from a loosely-knit team of hackers across the Net. It aims towards POSIX compliance.

In this article I am trying to describe the various differences between Unix and Linux under the following headings -

1. History
2. usage
3. Cost
4. GUI
5. Security
6. Future OS

History

UNIX was created in the 1960s by the AT&T Bell Labs (Ken Thompson and Dennis Ritchie) and first commercially UNIX OS became available in 1970. First release of Unix was having a command line interpreter and some small utility programs with future extension for the multitasking and UNIX evolved from there.

In 1991, Linus Torvalds began working on a UNIX like OS known as Minix. The Minix source code was freely available under GNU GPL and he successfully modified this code for use on x86 PC systems. By September 1991, Torvalds has successfully completed the first Linux kernel designed for PCs. This kernel included various system utilities and libraries from the GNU project to create a usable operating system based completely on open source code.

Usage

The UNIX operating system is used in internet servers, workstations & PCs. Backbone of the majority of finance infastructure and many 24x365 high availability solutions.
Linux can be installed on a wide variety of computer hardware, ranging from mobile phones, tablet computers and video game consoles, to mainframes and supercomputers.

Cost

Linux is Free (as it is opensource, except the case where you need a supported version i.e. RHEL). You can download it from the Internet or redistribute it under GNU licenses. You will see the best community support for Linux. Most UNIX like operating systems are not free (but this is changing fast, for example OpenSolaris UNIX). However, some Linux distributions such as Redhat / Novell provides additional Linux support, consultancy, bug fixing, and training for additional fees.

Credit:-Comparison between linux and unix operating system

The kernel is the system.

The Unix kernel makes it Unix, the Linux kernel makes it Linux. All the rest is software that interfaces with the kernel.

All the utilities you use, on either system, are functionally the same. You can comfortably develop and use software on Solaris and on Linux with little, if any, problems (mostly if you get down into using system calls in your programming, there are differences and you need to be aware of them).

Solaris, for example, is Unix and the utilities are generally AT&T. Linux uses open source utilities developed to be look- work alike but written from scratch to avoid licensing and copyright problems (those are a long story). The common tools, say sed, grep, ls and other every day useful software are functionally the same but not the same code.

Unix was developed at Bell Labs and written in C (in the beginning there was a small assembly language core that got you going on a particular platform but that vanished years ago). Unix is small, tight, and built for efficiency ("write functions and programs that do one thing and do it well"). The first Unix system I had ran quite well on a 50 MB disk and a few KB of RAM -- yes, kilobytes -- with a Motorola 68020 processor.

Linux is small and tight too. The utilities have gotten bloated over time with "enhancements" but, essentially, Linux is an efficient system that works just fine. You sit down at a terminal and get logged in, you can't really tell the difference when you start doing work. That's not quite true of many Linux distributions that hide everything behind a GUI: click-'n'-drool is not quite so efficient. But, if you're writing programs, it's hard to tell what you're on.

Something you might notice on a Unix system is that the programs and utilities are, well, old. Written in the 60's, 70's and 80's. Wow. But, you know what? They've been working properly for all that time doing what they're intended to do with no fuss or bother. System updates come, get installed and things just keep on working almost 100% of the time (try that with Windows, eh).

To answer your question directly: not a heck of a lot. Unix and Linux are more parallel than radically different.

Hope this helps some.

To add to the above, Linux was written to the published Unix standards. The code was copywrite, but the standards were published.

Consequently, Linux looks and acts like Unix, but Linux code was not derived from Unix code in any way. A search for the "history of Linux" will turn up many useful articles. This is a good one: http://tldp.org/LDP/intro-linux/html/sect_01_01.html

Nonsense.

If you say Unix is based on the AT&T Unix, then BSD Unix is a Unix clone, just like Linux.
While at that time nobody said that BSD was not Unix.

A smart guy named Linus Torvalds started creating a "Unix-like" kernel in his dorm room. He didn't like everything that Unix did, so he changed some things. (Imagine that ... :rolleyes:) Linus wrote the original kernel: the "hardware control" layer at the very center of the thing, and he continues to drive that project to this day. (Now, that kernel runs on more than 20 very-different hardware platforms.)

Another smart guy known best as "RMS" took on the very-ambitious project of writing a C-compiler that expanded into a language suite, as well as "new and improved" Unix-like command-line utilities. He (and his collaborators ...) did a damned-good job of it, too.

And then, the Internet. Open source, protected by software licensing agreements that have been tested and upheld in courts around the world. Resulting in: collaborative software development, owned by no "one" one.

The combined, and continual, efforts of (now ...) thousands of people worldwide, collaborating on what has become a massive software development effort ... gave us "the Linux System." It's the product of the confluence of several significant projects, united by the Internet (and by very cool version-control software).

It's a software asset now worth billions of dollars, which no one could have afforded to produce had the conventional business-model been used. But, it wasn't ...

Various people and companies tried to "take ownership of" the thing, ex post facto, and some of them spent years and millions of dollars in court ... and lost.

And so, we have it: several similar operating systems, one of them completely open-source. Unix is the "granddaddy" and the original inspiration, but ... "GNU's Not Unix.™"

AT&T was restricted from selling Unix but they could (and did) give it away to colleges and universities, perhaps most significantly to University of California Berkeley where Bill Joy (the guy that did the visual mode of the ex editor -- that would be vi) drove students to fiddle with the software and see what they could come up with (one was C-Shell). The results were the Berkeley Software Distribution (BSD) that turned out to be Unix with enhancements; I'm not so sure how enhanced C-Shell is but there you are, some people love being flogged. That was around the time of AT&T System 3.

AT&T System V (R4) includes Berkeley enhancements in system libraries and some other things and the folks at Berkeley (read the bosses) decided that they ought to go their own way with BSD which was Unix with enhancements. Sun Microsystems first released hardware running BSD (they called it Sun OS because they, Sun, had fiddled and twiddled with BSD but later replaced Sun OS with Solaris which is System V (R4) with Berkeley enhancements and Sun enhancements and a really nice Unix operating system. Lately I believe the University bailed out completely and I dunno what's going on with it or if BSD is a Linux or Unix kernel (and I really don't give a hoot, never did like BSD to begin with).

Those of us out here in the hustings had to navigate through the tangled web of the AT&T breakup which, along with creating the Baby Bells, sold Unix to some really bad actors (that proceeded to sue everybody running Unix and, happily went bust doing it). And, well, that was that. UC Berkeley got out of the software business, Sun is owned by Oracle, Apple OS X is BSD (as far as I know -- you can count on Apple to keep deep, dark, secrets about everything they do) and Linus invented Linux and saved the world.

And between the Linux kernel and the Free Software Foundation (and thousands of contributions from individuals, foundations and corporations) we get to live and work in a universe inspired by some really smart guys at Bell Labs that just wanted to not need to reinvent the wheel every time a new hardware platform showed up.

Wow.

Well... the version 0 was written in assembly (and called Unics). But it was rewritten in C in 1972 as soon as the compiler was available. By the time it was "available" for others (1973), the system (now called UNIX) was all C, with a couple KB for assembly (interrupt interface, system call interface, context switching, and memory management interfaces). In addition the system call interface includes the user library for system calls.

Written in C since 1972 (I think that would have made it version 1). Well before V6. V0 was assembly (and not on the PDP-11 either, it was on a PDP-7 http://www.catb.org/esr/writings/tao...l/ch02s01.html.

Actually, the whole point of developing C was to write Unix in it! Early operating systems were written in assembly language, which meant they needed to write a new OS for each new mainframe design. The idea of Unix was that if you wrote the OS in a high-level language, you'd just need to write a new compiler for each new computer. But what language? Hardly Fortran. They looked at developing BCPL but eventually gave up on it. They'd been referring to that as B, so they called the new language C. Incidentally, the reason why Unix has the X window system is that the prototype had been called (what else?) W.

Unix®, Linux®, Posix®, AIX®, and GNU® are all registered trademarks in the United States. And they all refer to different things.

(So, when people refer to "GNU Linux," they are actually abusing two registered trademarks having two different owners! Legally speaking, you can't do that.)

As some very expensive lawyers discovered in a long legal defeat documented at groklaw.net, Linux® is an entirely original operating system which shares no source-code with Unix® but which re-implements (and, improves upon) much of its API and operating concepts. Of course, Linux® today has gone much beyond its original inspirations, as has Unix.® The teams responsible for both products are of course very aware of one another and cooperate closely on many things, although their efforts diverge in some areas.