What is UNIX, Anyway?

Lieutenant writes "Technology professionals have loosely used the term "UNIX" since the first person had to explain the difference between the Berkeley and AT&T flavors, so it's not surprising to find as many UNIX standards as there are versions of the operating system. Peter Seebach wades through the wellspring of UNIX standards and sorts them out for you, concluding that the rumors of the death of UNIX are (as usual) greatly exaggerated."

Not a bad article.

This editorial definitely seems to be for marketing purposes, being both hosted by IBM and directly confrontational about Microsoft. Still, interesting enough article; it's always tough to be brief and to the point about such a complicated subject. I especially like the author's point about the liquidity of the Microsoft "standard" API which is so touted as a counterpoint to *nix implementation -- DOS, Win16, OS/2, Win32, WinNT, WinXP, .NET, Vista... versus POSIX. Yeah, he's right, it sounds pretty ridiculous when you put it that way. That being said, the article's pretty light on the details. For those rare individuals interested in reading more than TFA, here's a little more info on UNIX [wikipedia.org] and the POSIX standard. [wikipedia.org]

Re:Not a bad article.

For the history of Unix (timeline), read this one:
http://www.levenez.com/unix/ [levenez.com]

Re:Not a bad article.

Hosted by IBM just because it's a regular column on standardization. In all the years I've written for IBM, the only edit they've ever made on such grounds is that they changed the word "Belkin" to the name "Company X" in my article about Belkin's packet-hijacking routers. Oh, wait; I think they disliked a couple of comments I made about Verisign once. Mostly, if there's no obvious liability, they don't get involved.

If only that were true!

Clearly you were never forced to program anything to the Win32 API.

There's a common subset of functions available on both 9x and NT flavors of Windows. (With different bugs and sometimes different supported flags, different restrictions on use, etc). Then there's a bunch of functions that only work on NT-based flavors of Windows, not 9x-based. And the opposite is also true. Then XP came along, then Server 2003, each adding a bunch of new stuff to the API that Microsoft (unfortunately) did not go back and also add to the earlier versions of Windows.

There really are at least 3 distinct flavors of the Win32 API, and you have to be careful what functions you use if you want your program to run on all three of them.

For an example, check out the documentation for the CreateWindowEx function [microsoft.com].

If you scroll to the bottom, they describe several of the differences in the behaviour of this function on different versions of Windows ranging from 95 to XP.

This situation could have been avoided if Microsoft had had the foresight to separate the Win32 API implementation from the rest of the OS so it could be upgraded independently.

Re:If only that were true!

Then there's a bunch of functions that only work on NT-based flavors of Windows, not 9x-based. And the opposite is also true. Then XP came along, then Server 2003, each adding a bunch of new stuff to the API that Microsoft (unfortunately) did not go back and also add to the earlier versions of Windows.

I can only think of one feature that's available on Windows 9x but not NT, which isn't part of the Internet Explorer toolkit, and it's a very rarely used feature (although it's just the kind of thing I use). Almost universally, the API on NT is a superset of that available on 9x; though it is true that occasionally some small implementation details different between the two.

Then XP came along, then Server 2003, each adding a bunch of new stuff to the API that Microsoft (unfortunately) did not go back and also add to the earlier versions of Windows.

Correct. The Windows API evolves over time, adding new and often useful features to new versions, often involving new features of the kernel. In nearly all cases these changes are backwards compatible.

There really are at least 3 distinct flavors of the Win32 API, and you have to be careful what functions you use if you want your program to run on all three of them.

Windows 9x, Windows NT, and..? Well, I suppose you could call the ANSI/Unicode versions different, even though the differences between the implementations are usually very clear-cut (i.e. path strings are always handled in certain different ways).

For an example, check out the documentation for the CreateWindowEx function.

If you scroll to the bottom, they describe several of the differences in the behaviour of this function on different versions of Windows ranging from 95 to XP.

That serves as an excellent demonstration of what I've said: the differences are usually minor enough to not be a concern, and that new features are added in a backward compatible way. Take a look: one of those differences refers to a feature that was added in XP (WS_EX_COMPOSITED), another refers to a kernel limitation of 9x, and the third refers to a feature that was added in 2000. Of those, the only "serious" one is the 9x kernel limitation, and even then it's not particularly important.

it's ok

i don't take any reports of UNIX's death as fact without a Netcraft confirmation.

Re:it's ok

Have they said anything about Slashdot dying?

There are 11 whole posts (so far) on a story where geeks get to stroke their egos by showing their ignorance and calling everything in sight a version of Unix.

Heck, I didn't even see anybody post a *BSD is Dying troll.

Re:it's ok

Heck, I didn't even see anybody post a *BSD is Dying troll.

That's because it is already dead.

Single Unix Standard, Version 3

As a programmer, that's what I really consider as Unix - sus v3 [unix.org].

I code for this API and the sources end up being source compatible. But then there are library paths and stuff, which is why even something as homogenous as Linux is forced to create LSB [linuxbase.org] standard. The API standard OTOH, is crystal clear - look at the API tables [unix.org] in terms of availability. And yeah, my project is called Portable.net [gnu.org], so I've put in my time writing portable code for various platforms (even BeOS [dotgnu.info] and SkyOS [osnews.com]). Wish the threading models worked the same, that's all :)

There is just *nix ... just *nix and VMS - everything else is somewhere in between.

Re:Single Unix Standard, Version 3

I code for this API and the sources end up being source compatible.

Oh boy, you haven't deployed any code in the real world, have you?

The total number of conformant implementations of SuSv3 (or even v2) is zero. None. Zip. Zilch. Nada.

Everything, including the linux/glibc, BSD, and proprietary unix-like platforms, differs from the spec in subtle and complicated ways. SuS and POSIX are paper standards, not things that you will encounter in software. They're fodder for managers and marketing; they have little or no engineering value. And the differences are important to the point where you have to modify the source of your program to support other platforms, once the program becomes sufficiently complicated. As a rule, a complex program with no platform-specific hacks is a complex program that has bugs on some platforms which have not been found/fixed yet.

This isn't likely to change in a useful manner. Most of the platforms approximate SuS/POSIX as closely as they can without breaking existing applications. Successive revisions of SuS/POSIX become more vague in order to encompass more of the things that happen in the real world. So a good way to look at these two is to consider them an inefficient and fairly inaccurate attempt at documenting the common features of a set of platforms. If this process was completed perfectly, the resulting document would be so vague and cover so many platform-specific hacks that it would be of limited value. Since the documents get updated much more slowly than the software, they will probably never be completed to a satisfactory level of accuracy.

Re:Single Unix Standard, Version 3

Well, that's certainly a negative way to put it, but what if anything could they do any better? It's not like it would be particularly practical or reasonable for unix vendors at this stage of unix history to break backwards compatibility for the sake of future compatibility.

So, the unix vendors do the next best thing: they make whatever changes they can to bring their platforms to uniformity without breaking backwards compatibility, and they maintain a common standards document that documents the cross-platform compatible functionality. When they inevitably make mistakes in the documentation process, they remove specifications that they cannot implement complatibly in all unix systems.

The most important point here is the intent of the unix vendors: They are working towards compatibility wherever they can, and they are striving for accurate documentation of the compatible functionality. There's nothing to disparage in their actions, even if they make the occasional mistake -- at least they are improving all the time.

Even linux developers are known to deviate from the SUS occasionally, but they too do strive to implement the standard wherever possible. Yes, the Single Unix Specification is incomplete and flawed, but it's the best thing we've got.

First Sale Doctrine

FTFA:

A single programmer who wants a copy of the POSIX specification would have to pay US$974 for it. That gets a one-year subscription; you are not licensed to continue referring to the standard thereafter.

What about the first sale doctrine [wikipedia.org]? Do they really contend that you cannot "refer" to the standard after one year? Do they do a mind wipe? Or is just that your subscription for updates lapses after one year?

Re:First Sale Doctrine

You can (legally) get it for free at unix.org and opengroup.org. An individual paying a $974 annual fee for it has more money than brains.

UNIX ?

UNIX is not UNIX ! Hmm wait... no sorry I heard that or something close somewhere else.

Re:UNIX ?

XINU [wikipedia.org] Is Not Unix.

(It's actually a giant space clam that wants you to give all your money to L Ron Hubbard)

old paradigms

isn't unix:

- everything is a file
- every file is a stream of bytes
- do one thing and one thing well, Keep It Simple Stupid
- human readable/editable config files
- principle of least privilege
- services as daemon processes
- clear separation of kernel and userland (although this one is debatable)
- multi-user environment (despite the name)
- remote access facilities
- console/automation oriented, powerful shells
- ./configure && make && make install

?

well, that's just a few things that come to my (linux/bsd slanted) view of what (a modern) unix is...

Re:old paradigms

You've used a couple of Plan 9 and Sprite paradigms, some things which never applied to Unix[*], a load which apply to operating systems in general and an implementation artefact of GNU autoconf. I really hope that's not Unix....

[*]"least privilege" - MACs would predate setuid() if that were the case. For instance

Re:old paradigms

To take the specific point of MACs, if UNIX was about giving you the least privilege necessary to get your job done, then the concept of setuid (which gives you *all* the privileges available) would never have existed. Tools like sudo, solaris profiles, SEDarwin/SEBSD and the like have come up to try and plug this privilege leak but fundamentally, Unix has a binary privilege model. You either have none, or you have them all. More generally, I think it's hard to fundamentally sum up Unix (without using one of the technical definitions, such as "something which implements SUS"); when it comes down to it it's a C language API and a set of tools which implement that API, running a multiuser multitasking OS. I think a good description would be "an OS that one person can grok"...

Correlation, Causation, LSD

In some cases, existing practice in a field reflects a decision a college student at Berkeley made at 3 AM.

"There were only two things to come out of Berkeley in the 60's, LSD and Unix. I doubt that is a coincidence."

MISQUOTE

"There are two major products that came out of Berkeley: LSD and UNIX. We don't believe this to be a coincidence." - Jeremy S. Anderson

Re:I vote for syslog

You've never read a Sendmail.cf file, have you?

Re:I vote for syslog

To be fair, he did say "drug induced". Sendmail.cf (Heck, M4 in its entirity) clearly is not drug induced. It is a many tentacled being which slithered forth from the darkest nether regions of hell to lay waste to the minds of humanity. On a good day.

great, we slashdotted IBM and Coral Cache :-P

IBM (http://www-128.ibm.com/developerworks/power/libra ry/pa-spec13/?ca=dgr-lnxw01UnixStandard [ibm.com]):

Our apologies The IBM developerWorks Web site is currently under maintenance. Please try again later. Thank you.

Coral Cache (http://www.ibm.com.nyud.net:8090/developerworks/p ower/library/pa-spec13/?ca=dgr-lnxw01UnixStandard [nyud.net]) :

Error: 500 Internal Server Error Server CoralWebPrx/0.1.16 (See http://coralcdn.org/ [coralcdn.org]) at 216.165.109.81:8090

Makes one smile :-)

Had to be said.

"The nice thing about standards [wikipedia.org] is that there are so many to choose from." -- Andrew S. Tanenbaum, author of Minix.

The Spirit of UNIX

Probably the oldest standard that people still refer to is AT&T's 1985 System V Interface Definition (SVID).

I routinely use printed Seventh Edition (Bell Labs Research) UNIX manuals, even when writing C for Linux. It also helps one remain blissfully ignorant of the 'cat -v' option and similar excrescences. Also the Tenth Edition UNIX manuals. I have to remember the changes introduced by Standard C and the like, but it's convenient to have the essence of the modern-day manual in printed form. Of course, there are some people out there who delight in using Fifth, Sixth, Seventh etc Editions on PDP-11s etc - see the PDP-11 UNIX Preservation Society, http://minnie.tuhs.org/PUPS/ [tuhs.org]. I wish I had a larger garage! How much would a PDP-11/40 cost me now, anyway?

Peter Salus' book "A Quarter Century of UNIX", Addison-Wesley, 1994 (corrected 1995), ISBN 0-201-547771-5 is a good informal UNIX history.

"Those who do not understand UNIX are condemned to reinvent it -- badly."
                                                  -- Henry Spencer

Correction

That's ISBN 0-201-54777-5, or 978-0-201-54777-1.

Answer

Unix is not GNU.

UNIX hater's handbook.

Unix hater's handbook [simson.net]

it's funny AND true.

/ seriously thinks UNIX like systems need to go the way of VAXen.
// well, actually not so much the systems themselves, but the assinine UNIX mentality of "harder is better" and "more documentation eliminates the need for good design.", which set back Computer Science departments and academia 15 years behind industry.
/// fortunately, one of the unintended side-effects of Linux is that the mentality, at least amongst Linux users, is slowly, ever so slowly, fading away.

Re:UNIX hater's handbook.

// well, actually not so much the systems themselves, but the assinine UNIX mentality of "harder is better" and "more documentation eliminates the need for good design.", which set back Computer Science departments and academia 15 years behind industry.
/// fortunately, one of the unintended side-effects of Linux is that the mentality, at least amongst Linux users, is slowly, ever so slowly, fading away.

Hmm.. yes, in /// you say that Linux programmers are going away from //. They are, they're just not doing the documentation. ;-)

Re:UNIX hater's handbook.

Hmm.. yes, in /// you say that Linux programmers are going away from //. They are, they're just not doing the documentation. ;-)

Which is why we have BSD.

Re:UNIX hater's handbook.

I think it comes down to this: when a user's input results in some unexpected output or if the user was unable or found it difficult to tell the computer what he wanted to do, the UNIXine (and this applies to GNU stuff, Linux stuff, and BSD stuff equally) response for many years was "the user made an error" or "the user's lack of knowledge is the core of the problem."

This attitude was (and to a great degree still is, though somewhat less than before) is the single most cancerous and evil mode of thinking in computer science, and yet it went widely accepted ("unchallenged" would be wrong) in Unix circles and associated hanger-on CS departments for years. The correct attitude should have been "if users are making the same mistakes and being tripped up in the same places over and over again, then clearly the fault lies with the tools themsleves."

Now, I'm sure if I go through the usual examples of this theory, I'll get back the usual result: some unenlightened idiot telling me that EMACS and/or the CLI are faster at the end of the day and therefore better, and that the problem is simply "more training." Thankfully, in 2006, I hope I don't have to explain why this mode of thinking is outdated (well, never right in the first place) nonsense, since most of you have finally woken up to these facts:

• Usability and speed are orthogonal to each other. You do NOT need to give up speed to gain more usability, and vice versa. The trick is something called GOOD DESIGN. Bad design simply trades off one for another. Good design at least imporves on one front without diminishing another.
• A long manual is a hallmark of bad design. Did you need to have a manual to start using, say, a web browser? No. Why should, say, a text editor be any different?
• i) The UNIX philosophy of "make tools small and atomic" is not necessarily bad from a deep technical standpoint, but this doesnt mean the user necesarily has to directly interact with those tools and ii) one doesn't have to be a "Windows for Dummies" esque user to benefit from well built tools. There are lots of real life examples of progress in this, from the steady emergence of (still often highly flawed, but far better than what was before) high-level languages/environments like PhP, Perl, Gnome, KDE, and so forth. There is ABSOLUTELY no reason why I can't be a UNIX guru and haven't the slightest idea what the command-line arguments to 'tar' are off the top of my head.

Bring on the 'yesbuts...' from the dinosaurs and self-annointed high priests...

ibm slashdotted?

what? what is going on?
Our apologies

The IBM developerWorks Web site is currently under maintenance.
Please try again later.

Thank you.

IBM On demand servers slashdotted?!

Our apologies

The IBM developerWorks Web site is currently under maintenance.
Please try again later.

Thank you.

!!

Well, maybe they're running Windows on demand!

Define it by its limitations

Maybe it would be easier to see what Unix is by pointing out the weaknesses, reading "The Unix Hater's Handbook" for instance:

http://web.mit.edu/~simsong/www/ugh.pdf [mit.edu]

Which, despite the name is not a mindless bashfest and is interesting.

--Plan9/Inferno and Lisp Machine advocate--

Surely, if Unix was a stable and standardised API

...we, erm, wouldn't need Autoconf [gnu.org]?

unix

unix brings me back to college days

back them doing assignments on windows was more fun than unix command line...

alot of people on our course got put off from ever touching unix and linux thanks to this

Last time I checked, UNIX was a trademark

Yup. UNIX isn't an OS. It's a trademark and a standard. And Linux is a kernel, not an OS.

http://www.unix.org/ [unix.org]
http://www.kernel.org/ [kernel.org]

Also Windows aren't OS. It's an opening constructed in a wall or roof that functions to admit light or air.

Lastly Apple is not a company. It's a god damn fruit. Why is that ESPECIALLY MacOS users don't seem to get that Apple Computers are PC!?!? Try to ask a MacOS user this. "Do you have a PC?" I bet, 99% of them will say "No, I don't have PC, but I have a Mac." WTF??

still an amazing OS

I've been working with Unix/Solaris/SunOS/Linux/AIX/AUX/BSD/ATT Unix, et. al. now for over twenty years. I mostly love the environment, I'm self-taught, and never have stopped discovering new and cool (and sometimes amazing) things about how Unix works.

I've pretty much always always been able to sit down and immediately be productive in a Unix environment. Things are stored and arranged in a surprisingly consistent way (not always in the same places, but one of a few organizations (/etc vs. /usr/etc)), and for those hard to find arrangements you need only know "find".

Considering how many different Unixes there are it's actually impressive how compatible and consistent they are across the Unix universe. It's only my opinion, but I find adapting and adjusting to the Unixes far easier than the various versions of Windows.

portability wtf

"With rare exceptions, porting hassles between UNIX systems are long forgotten."

Yeah right. We're down to complaining about porting apps between versions of the same distribution of linux and here's a guy claiming that porting hassles between UNIX systems ar long forgotten. Come on, you can't claim that with a straight face even if you are working for Microsoft.

It's not like your 1993 binary of wolfenstein will work out of the box on win XP but the chances of binaries from that era doing something are a lot higher than say running any unix binary from that era on the latest Red Hat/Debian/Whatever. Compiling with the latest GCC almost guarantees running into porting issues, never mind the particular OS you are doing that on. Probably hello world works fine but anything doing something less trivial is likely to not work at all. Generally problems increase as you (necessarily for non trivial stuff) depend on libraries not part of any of the Unix standards. For example, these standards do not cover anything related to graphics or user interfaces so you're fucked if your app is non trivial enough to include a (G)UI.

Another Amiga mention...

heheheh I'm beginning to think that finding a mention of Amiga in articles covering aged, long-standing, or break-through technologies or philosophies, or just places of honor in computing history, is almost like a "Where's Waldo" using web pages as the pictures :)

(Uh, are we a cult yet?)

Linux vs UNIX

In all fairness, it all came from the same tradition - but when AT&T took back the copyright on their original UNIX implementation - that's when it started to seriously fragment into AIX, HPUX, APUX, DGUX, Solaris, and BSD's. Evolution slowed down drastically and left the UNIX community wide open enough for Microsoft to drive a train thru. To compensate, the UNIX community tried to force thru all these standards initiatives (renember CDE?, Motif), but they always failed to stem the tide.

Then Linux came along, and started to undo the damage that the copyright fragmenting caused to begin with because it was under the GPL, and ever since then it has been the beginning of the end for Microsoft and Linux has taken off in the server space and now it's getting ready to attack the desktop. Moral: free markets are about freedoms and not markets. When you have freedoms the markets will take care of themselves, but when you sacrifice freedoms for markets - you will eventually loose both.

'it's the standard that isn't'

isn't it? that what I was told...

Unix you say?

A lady struck up a conversation with me on an airplane.

• Her: "And where are you going?"
• Me: "I'm going to San Francisco to a UNIX convention."
• Her: "Eunuchs convention? I didn't know there were that many of you."

From http://rinkworks.com/stupid/cs_comeagain.shtml [rinkworks.com]

So true

One of the best quotes I've ever heard was from a colleague of mine,

"Unix isn't."

So What is UNIX?!

I think that the whole discussion can be summed up, just as the article says, with:
"We reject kings, presidents and voting. We believe in rough consensus and running code." -- Dave Clark

So in answer to "What is UNIX?", UNIX is code that runs based on general agreement of the masses. This is why it will not die, even LSB is discussed in the article and rightly so, it falls into the same category. A loosely held standard that defines what the general masses of Linux distributions use.

No hard and fast standard would ever survive in the *nix world, ever system is unique to its purpose.

Nice article, IBM churn them out and every so often a good one turns up.

Re:Unix is in everything

(Unix->VMS->WNT)
Only an american could be so ignorant of history. VMS [wikipedia.org]VMS did indeed lead to NT, but had nothing to do with unix.

Re:Unix is in everything

Indeed, the story of UNIX today is depicted in this documentary [imdb.com].

Re:Unix is in everything

VMS is absolutely nothing like Unix.

Re:Unix is in everything

Huh? Unix isn't remotely related to VMS.

Re:mnennnnn

That command is only valid for System V type variants.

Re:mnennnnn

kytf jxcjvoixcvj :: POIJP>>IPOhghghgIPO

That command is only valid for System V type variants.

Ah. I see you've been forced to use AIX as well!

Re:Say what you want about Windows.

Are you sure about that? I confess that I haven't tried running old binaries on new systems (with source code available there doesn't seem to be much need) but I know that the Linus, at least, is dogmatic about making sure that the Linux system call interface is always backwards compatible. You can run binaries that were compiled against Linux < 1 unmodified today.

I'm not as confident that the same is true of userspace, but I bet it's not that different. Where there have been incompatible user-space ABI changes (glibc, gtk) the distributions I've used make the older versions available and useable alongside the newer versions.

Re:Say what you want about Windows.

[i]"The fact that MS userland is hooked into the registry and alows root level access is the reason that crap binaries are so easy to create."[/i]

For a sentence that neither makes sense, nor contains any accurate information, it sure contains a ton of jargon.

Are you a consultant that specializes in Windows>UNIX migrations?

Re:Choc-a-lates

Or...

"UNIX is like a box of chocolates. You pick one that looks nice, and it turns out to be really hard."