I'm just asking out of curiosity, is there a way to obtain a 'pure' so to say copy of Unix? So, not OS X or Linux with Unix in the background, but simply Unix..

  • 1
    Linux is GNU software based and therefore not unix... Check what GNU stands for ^_~ Mar 8, 2012 at 10:11
  • 6
    Unix is dead. Long-live Unix!
    – mikeserv
    Jun 22, 2014 at 3:11
  • 1
    The closest to original version of Unix I've been able to find for free online is AT&T UNIX System V Release 4 Version 2.1. You can get it at winworldpc.com.
    – Strato1
    Jul 3, 2014 at 17:11
  • 1
    In my opinion the only real UNIX is Unixv7(1979) from Bell labs and SYSTEM-III IV from AT&T,the other are similar,derived or Unix-like
    – elbarna
    May 11, 2015 at 0:50
  • A bit too late, but here you go tuhs.org
    – r0mzk
    May 8, 2021 at 13:28

13 Answers 13


Unix as a standalone entity doesn't exist as a modern operating system.

As indicated by the comments for unix-derivatives:

Several systems started with Unix source code, but this was written out over time so that no original Unix code remains. The best known examples are OpenSolaris, FreeBSD, NetBSD and OpenBSD.

FreeBSD 5.3   2004-08
OpenBSD 4.6   2009-10
NetBSD 5.0.2  2010-02
OpenSolaris build 135 2010-03

and unix-clones

There have been many systems which implement the Unix system calls, library APIs and commands, but which did not include any original Unix source code. Here is a small selection.

Minix 1.1 1987-01
Xinu  1987-01
Minix 1.5 1989-11
Linux 0.96c   1992-07
Coherent 4.2  1994-12
Minix 2.0 1996-10
Linux    2010-04

Modern distributions don't contain any original unix code, or at least - none of the open source variants that are freely available.

  • 1
    Oh okay. I believe that answers my question then. Mar 8, 2012 at 10:18
  • 11
    And he never returned. Last seen March 8 2012. Mar 31, 2016 at 17:58
  • I believe that the BSDs do contain original code. I'm pretty sure most files have been rewritten by now, but I'd be surprise if there wasn't a fragment of some file still intact.
    – Kusalananda
    Apr 10, 2017 at 7:32
  • 1
    Wait, what? Unix does exist. See the other answer...
    – sudo
    May 8, 2017 at 21:07
  • As you said are the "UNIX System V", "Version 6 Unix", etc not operating systems/ distributions ? Feb 27, 2018 at 9:01

If you want to be hard core, you can run a V7 Unix on a PDP-11 emulator. I've done this, and it had better performance than VAX running 4.2BSD I used in college.

  • Cool. We admin'd the same way back when. Always laughed at the paper tape boot loader on our DG mainframe.
    – Arcege
    Mar 8, 2012 at 19:19
  • That's pretty cool. So it pretty much simulates an original version of Unix? Mar 8, 2012 at 19:33
  • 12
    It is the original version of Unix, running on simulated hardware. And the source is available too. Reading through the source of a C compiler written by Dennis Ritchie himself was kind of a religious experience for me...
    – TMN
    Mar 8, 2012 at 19:36

This image shows a simplified version of the history of the unix-like operating systems. Depending on what you call the "one true unix system", you may download it as open source or you can buy a license for it. The latter will be expensive if at all possible.

For more in depth information, see unix history as pointed out by AProgrammer in the comment.

  • 6
    Well, that's a simplified version of the history. See levenez.com/unix for a more complete one. Mar 8, 2012 at 10:12

I know, it's a very old post. But if someone wants to try out classic Unix, it is available as a virtual box image through http://www.nordier.com/v7x86/releases/v7x86-0.8a-vm.zip

It is the first public release of V7/x86, a port of UNIX version 7 to x86 based PCs.

For a quick guide, refer to this http://www.nordier.com/articles/v7x86_vbox.html


As soon as Unix got out of the Bell Labs in 74 or so, Unix became a family of OS more than an OS. And since 89, there have been no release on the original branch. The trademark "Unix" has changed multiple time of owner and currently it is defined by a set of interface and you can buy the right to use it if you show that you comply to the current definition.

You may be able to use one of the ATT one on an emulator (I've seen some packaging for some release, but not the latest one).

Commercial Unix (Solaris, AIX, HP-UX) have usually taken the pain to go through the certification process. Solaris was available at no cost from Sun (I think Oracle changed the condition) and has been put in open source. Going that path is probably the cheapest way to get something near of what has been allowed to use the label. But affirming that it is a "pure" unix is under debate. Some BSD derivatives have good arguments for "purity" as well.


What do you mean by UNIX? The last "true" Bell Labs unix was Version 10 from 1989, never released to the public. Most modern UNIXes descend ultimately from Version 7. The history of UNIXes is very messy, a brief version is available here. From there, it gets very messy. You can trace UNIX from there to either (closed-source) System V UNIX or BSD. If you want to go down the BSD path, FreeBSD is a good option. For a System V-like system, your only real free option would be OpenSolaris. But nowadays, Linux is as pure a unix-like system as any, with its own, even messier heritage. (You can get a taste of it here.)


Pure UNIX? If you mean UNIX of Ken Thompson, you should take a look at xv6. It's a clone of UNIX V-6 for x-86 hardware. Be warned though that not a commercial OS. It was written as a teaching aid for a course in MIT.


Yes you can use "pure" UNIX System V version 4.0 from AT&T bell lab

I am using this this UNIX from 6 Month ago, it's Unix.

pure command line is available Xwindows NOT available present.

from here you can download and install in Oracle Virtual box

  • How did you install the package? It contains .img files but Virual box or Hyper-V doesn't support installing from .img. I tried changing the extension to .iso as suggested in google. But no luck.
    – Dush
    Dec 2, 2017 at 6:26
  • 1
    Hello #Dush Thank you for showing interest in installing Unix System V . If you need to know about process to install Unix System V and Packages belong to it . you can refer following Video link . Thank You . youtube.com/watch?v=6P57ukAtCGs Dec 3, 2017 at 8:48

By saying one wants ‘pure’ Unix, it is implied that they want the latest version of Bell Lab’s System V. Not GNU/Linux, not BSD, not macOS.

One can indeed still obtain ‘pure’ Unix from its current owner: Xinuos.

The name is now officially SCO UnixWare 7 Definitive 2018, and you can learn about it here:


Xinous also provides OpenServer 5 Definitive 2018 (a descendant of Xenix), and other FreeBSD-based and SCO Unix-based operating systems.



You mean something like


  • Maybe, I'm just looking for a non GUI based system pretty much, that runs on Unix. Mar 8, 2012 at 10:15
  • If it was not unix i would recommend linuxfromscratch.org Mar 8, 2012 at 10:17
  • 3
    @JamesLitewski. you got the things in the reverse order. Undex Unix, the GUI is mostly an application layer which run over the OS. Any variant will easily provide you with a command line interface and just that (with the potential exception of MacOS about which I know very little). Mar 8, 2012 at 10:33
  • 9
    @tonymarschall, I'd not recommend linux from scratch to someone not yet familiar with Unix. Mar 8, 2012 at 10:33

You can compile unix from its source, but that would require the source its self and removing the rest of the code that at this point is useless. the code can be found at: http://www.tuhs.org/Archive/PDP-11/Distributions/usdl/bostic_pwb.tar.gz and compiling it with gcc and nasm.


I would consider UNIX sytem V release 4/5 to be as near as you could get to "real UNIX". Today in December 2016, I consider current Debian Linux, 8,(having and just installed then dumped it.) As having drifted sufficently far away from the 20th Century Philosopy of UNIX, (IMHO), after it dumped the SysV init and broke all my cutomized boot scrips and overwrote my custom config files. Thankfully I have sufficent backups to restore my previous running system. I say the above; as someone who has been using AT&T UNIX, in its various incarnations for way on almost 40 years. To do useful work with my systems rather thanspend all day tinkering with it. I am now looking for a way to bring up a fully functional SystemV R4 or 5 from the source code if need be. First thing is finding a K&R complient c compiler and other tools without too much hacking. But wonder if anyone has been here before me. My machines have AMD multicore x64 processors in them. Any help appreciated.


I hope I caught you in time before you got rid of all your scripts and config files. When Debian announced the switch to systemd, lots and lots of people did not like it and enough hated it enough to fork a distro with init intact from the stable branch. https://devuan.org/

In so far as UNIX, thus far, my investigation has led me to Lumios (and Solaris --still free if you are a developer or a tinkerer rather than a business) and Solaris as the closest to System V r4 but able to take full advantage of modern hardware. If you are happy with a BSD based version then I would vote for OpenBSD or OpenDarwin rather than FreeBSD because of the enhanced security. Incidentally, that is why I liked Lumios; they update their security far more often than Oracle (for the free version, once a year) and, even though they got there taking different roads, Lumios is functionally, IMHO, Solaris 11.3.

Now, if Bell Labs could be resurrected...


You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .