Unix vs. Linux: The Differences Between and Why It Matters
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Linux is everywhere these days. For the ultimate proof, look no further than Windows. With the release of the Windows Subsystem for Linux 2, Microsoft is shipping a Linux kernel with its operating system. Not that long ago, that would have seemed like an April Fools’ joke.

While Linux may provide the backbone for a large part of the internet, it wasn’t created from nothing. Before Linux, there was Unix, and the newer operating system owes much of the credit for its current popularity to ideas born in the 1970s and even the 1960s.

What Is Unix?

While Unix itself strives for simplicity, describing exactly what it is isn’t easy. The original Unix was an operating system from AT&T, but these days, the UNIX trademark belongs to the Open Group. Unix is also used as a category to describe an entire family of operating systems.

Then there is the Unix philosophy. This serves as a general guideline for Unix programs to follow, with the core being that each program should do one thing well. Instead of aiming to pack in every feature imaginable, a Unix tool should simply do its job, ideally producing output that can feed directly into the input of another program.

These days, there are many Unix variants available, in both free and commercial varieties.

What Is Linux?

Linux is another term that is more difficult to describe than you may imagine. Technically, a complete Linux distribution is a “Unix-like” operating system, but this is just the beginning.

Many people use Linux as a shorthand term for what would be more accurately described as GNU/Linux. Linux itself is just the kernel, the part of the operating system that does the core computing and interfaces with the hardware. The core utilities that run on top of this kernel are just as important.

Ubuntu desktop

GNU is a recursive acronym that stands for “GNU’s Not Unix.” The GNU project doesn’t contain any original Unix code, but provides all the utilities you would expect to find in a Unix operating system. This is a key difference between Unix and Linux.

Unix vs. Linux: A Brief History

Even the creators of Unix didn’t create it whole cloth. Instead, Ken Thompson and Dennis Ritchie took inspiration from an earlier operating system, Multics. At Bell Labs, these two took concepts from that operating system and rewrote their own in C, which Ritchie designed and helped develop.

Unix was not open-source software. Instead AT&T sold commercial licenses, but it wasn’t the only company working on Unix. Academics at Berkeley initially developed an add-on called the Berkeley Software Distribution, or BSD. Eventually BSD became its own complete Unix.

BSD command manual on macOS

In 1980s and into the 1990s, various companies began selling their own Unix offerings. These included IBM’s AIX, Sun’s Solaris, and Xenix, which later became SCO UNIX.

Linux Takes the World by Storm

In addition to the various Unix offerings, several Unix-like variants were available too. One of these was MINIX, which was intended for academic use. A software developer from Helsinki named Linus Torvalds was frustrated with the limitations of MINIX and aimed to create a similar kernel that could take advantage of the new PC he had bought.

At the same time, Richard Stallman was searching for a kernel. He had begun the GNU project in 1983, building free drop-in replacements for various Unix utilities. What he didn’t have at the time was a free, open-source kernel. Torvalds was already using GNU utilities with his kernel, and eventually so were others.

Linux quickly saw widespread interest. By the mid 1990s, the project had exploded in popularity due to the free-by-design nature of both the kernel and GNU toolset. Even as various other free Unix operating systems became available, the commercial nature of the first 20 years of Unix loomed over them. This still affects the Unix vs. Linux battle to this day.

How and Where Is Unix Used These Days?

Right now, popularity might be the main difference between Linux and Unix. That said, there are freely available Unix distributions that run many of the same software as Linux. The two most popular are FreeBSD and OpenBSD, both BSD variants, as the names imply.

Then, of course, there is Apple. Any Apple device you buy these days, be it a MacBook, iPhone, or even Apple Watch is running a Unix-like operating system. On an iPhone or Apple Watch, you would never know this from using them. That isn’t the case on a Mac computer though.

Darwin kernel info in macOS

Simply launch the Mac Terminal app, and you’ll have access to standard Unix utilities like ls, pwd, and even editors like vim. These tools can be quite powerful. For an introduction, see our beginner’s guide to the Mac terminal A Beginner's Guide to Using the Mac Terminal A Beginner's Guide to Using the Mac Terminal The Terminal app on Mac lets you accomplish all sorts of tasks using the command line. Here's a guide for Terminal beginners. Read More .

Linux Is Everywhere

Linux might be everywhere, but that doesn’t mean you see it. Android, the most popular mobile operating system in the world, is a fork of Linux. You wouldn’t know that from running it, but behind the scenes is a version of the Linux kernel modified for use in mobile devices.

Linux kernel info in Ubuntu

Much of the internet runs on Linux. While Windows and Unix variants power some servers, the vast majority of servers run a Linux distribution. Much of this has to do with the free nature of the operating system, but also how robust it is, which means less downtime. Unix isn’t less robust by any means, but the popularity of Linux means that most people will choose it in a Unix vs. Linux shootout.

One of the most high-profile appearances of Linux in the past few years is the Windows Subsystem for Linux. This lets you run Linux utilities on Windows, which is a major boon for web developers and software engineers. We have a guide on how to get started with the Windows Subsystem for Linux How to Get the Linux Bash Shell on Windows 10 How to Get the Linux Bash Shell on Windows 10 Need to use Linux no time to switch to a different PC or run a VM? Run Linux in Windows 10 with a Bash shell terminal instead! Read More .

Are You New to Unix or Linux?

Running a computer with either Unix or Linux is easier than ever before. Windows doesn’t run Linux at its core, but it’s still possible to at least run Linux on top of Windows. Any Apple device you buy has a variant of Unix at its core as well.

If you’re looking to run a “true” Linux on your computer, that’s easy as well. You could always install one of the countless Linux distributions on your computer yourself. Would you prefer a computer with Linux pre-installed? Look no further than our list of awesome Linux laptops 5 Awesome Linux Laptops You Can Buy Right Now 5 Awesome Linux Laptops You Can Buy Right Now Think Linux is hard to use? Many laptop makers offer Linux laptops that don't suffer from any driver or software faults. Read More .

Explore more about: Linux, Linux Distro, Unix.

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  1. Doc
    September 24, 2019 at 6:40 pm

    Don't forget that Sony's consoles from the PSX/PS1 to the PS4 (and future PS5) run a Linux core.

  2. vbill
    September 17, 2019 at 6:52 am

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  3. tgm
    July 6, 2019 at 3:21 am

    LOL. All this article did was to solidify how there is no difference between Unix and Linux.

    As someone with device driver and general C experience since the earlier days of unix (System III), I can tell you that there simply is no difference. The differences in the kernel? Absurd. There were FAR FAR bigger differences between System Vr4, and prior versions, (prior to SVr4, NO kernel /anywhere/ was preemptive---if your device driver did a while(1); your *entire* system ground to a halt) or between anything AT&T and BSD than there ever would be between whatever is left of "unix" and linux as it stands now.

    It's all just been a bunch on nonsense that pro-linux folks have been trumpeting just to skirt to legal battles with SCO, etc.

  4. A user
    January 15, 2015 at 2:28 pm

    On an iPhone in Safari there seems to be a redirect script on this page that prevents me from reading further than the first paragraph.

    • Me
      September 24, 2019 at 8:28 am

      That's because iPhone is Apple... and Apple is rotten to the core... rg&dfc

  5. Shawn
    December 18, 2014 at 11:05 pm

    And from the administrator's point of view, this unix/unix-like diffecies are last to care about. There are more differencies between solaris and mac os than between irix and linux, aix and linux, hp-ux and linux, tru64 and linux... It is because both of these unixes are far more bsd than systemV and both tend to have their own world in as much as possible while linux was written to resemble the pure systemV experience as much as possible. So the choice of sol and mox was cool to illustrate the difference between unix and unix-like, yeah.
    There was a challenge between unix vendors and i think every single one of them is great at something while it sucks at other things. For example IRIX is the only OS I have ever seen surviving dead swap with dialogue window informing that processes X, Y and Z were killed because they resided in swap that is offline and it went on, many times over and again and again. Every other system I tortured with this just simply froze sometimes even without any message...

  6. Shawn
    December 18, 2014 at 10:10 pm

    Oh well, that unix mean unix certified, which cost money and requires certain kind of discipline that is not very compatible with opensource software generaly. But as other said here, technicaly there is no way to forbid linux becoming unix while the naming thing is is a big unknown:
    1) Linus himself does not approve every single hack that someone does for his distro so it could even take some time before such a fact gets to attention.
    2) Some linux distributors (like google or even canonical) are not using the linux name very much and in the marketing perspective they are trying to sell android, chromeos or ubuntu. Thus for example when (if) android becomes unix, there would proly be no big refference to linux in it at that moment.
    MAC OS X has zero or next to zero from original unix, it is a derivative from freebsd and it is unix because it went thru the certification process. The same is true for QNX and some other not very common comercial OSes.

  7. Ramses Soto-Navarro
    November 24, 2014 at 11:59 am

    The downfall of UNIX to the glory of Linux has a lot to do with things such as greed, power and selfishness. From the beginning UNIX was an operating systems created in university laboratories using small gradual code using Assembly and C. It was an operating system available for all to play around with and use until somebody noticed how powerful it was and how it could be manipulated to accumulate wealth quickly. Everybody wanted to own something that was laboratory technology created by the students and faculty of universities. Many companies battled it out for dominance making UNIX a kept secret and an extremely-closed-source endeavor. UNIX was divided into many different versions all incompatible with each other and all using different standards (their own standards). Then came Linux...

    • Anonymous
      August 10, 2015 at 7:11 pm

      This is just flat out false. Unix was always a commercial product made by Bell Labs (AT&T). It was created by Ken Thompson and Dennis Ritchie for Bell Labs. Universities used Unix, but under a license, just as many use Windows licenses today. But it was most certainly not created by students. What happened though was universities wanted more freedom, and the University of California Berkeley made their own distribution of Unix, though still licensed Unix, called BSD. Then there was Minix, a free Unix clone made for universities, and FreeBSD, which was BSD but without the proprietary code. And then there was Richard Stallman and GNU. Stallman wanted to make software free, so he started work on GNU, a free Unix clone. Of the clones, some were created by professional programmers (GNU), some were created by academics (Andrew Tenenbaum a professor), and students (Linux).

      Linux came along when Linus Torvalds, as a student, was exposed to Minix at his university. Then he wanted that environment on his hind computer so he wrote the Linux kernel from scratch. And pretty soon people were pairing the Linux kernel with GNU utilities, since GNU still didn't have a working kernel at the time.

      So today Unix is dead. It's no longer licensed directly. There are Unix distributions out there that use the name, and pay to use it, and the proprietary bits of code, but the original Unix if no more. In large part because of the Unix clones like FreeBSD, Linux, and Minix. They were more popular because they were free. And as community support grew they were ported to more hardware.

      So saying that Unix was free to start with is flat out false. It was always proprietary, and still is. Companies still pay money to be "Unix Certified".

      But the real story is how Unix created a revolution in computing that was so popular it created a ton of free clones that were open and free. It would be like if someone decided to make a Windows clone and give it away for free. It wouldn't be Windows, but it would look like Windows, act like Windows, be functionally similar to Windows, and you could even write Windows applications that are easily ported to Windows. But the fact would remain that Windows was always proprietary, and the free clones came after it.

      You could argue that some Linux distributions, like RHEL, SUSE, and Oracle Linux took free software and tried to make a profit off of it. Then you'd be right in saying that software written by a student (Torvalds) was being turned into proprietary software. Heck you could even blame Apple; who took FreeBSD, the GCC, and Steve Jobs' Unix clone NeXT and combined them to make Darwin, which became OS X; and made it proprietary software. Then you'd be correct. But Unix was not written by students.

      • Thakur
        June 14, 2017 at 12:15 pm

        Thanks for the Lovely Info :-)

  8. MARK B
    November 21, 2014 at 1:01 am

    OY. The only real thing people need to know these days are:
    a) BSD unix (from berkley) and
    b) UNIX /Solaris (yes, solaris IS the decendant of the AT&T UNIX
    -- I wrote code almost 20 years ago to run the original package manager (from AT&T Unix) to work on Solaris (4 or 5?),

    versions of SUNos before Solaris were strictly BSD. After that, they did UNIX system V, but kept all the BSD binaries for compatibility.

    Yes, today some linux distributions choose either bsd style or SystemV style initializations.

    No there is no USABLE difference between them anymore
    Yes, NetBSD and that caliber are sometimes faster, yet harder to learn.

    and yes, the only UNIX (r) today is Solaris, because they essentially bought it after AT&T stumbled so badly

    Oh, and had a specific product manager at AT&T NOT been greedy and trying to make a profit in 1984, when they introduced the AT&T 7300 UNIX PC, and sold it at cost for $4,000 instead of the cost of $8,000 they sold it for, we would ALL be running AT&T UNIX today.

    stupid Jerks. One person's personal stupidity caused all of these problems.
    OH, and WINDOZE NT/2000/XP/whatever was built by the same guy who lead the team that developed VMS for DEC. (and I STILL hate the stupid ipconfig command instead of the LINUX ifconfig command!)

    cheers.
    A former AT&T Slave (before it was bought by BellSouth and ravaged even more)

  9. Tom Schenk
    November 20, 2014 at 9:50 pm

    Linux is called Unix-like instead of Unix because noone has paid to have it certified as meeting the single Unix specification. It has nothing to do with the code. If Redhat or Canonical or SuSE decided to fork out the money, they could have Linux certified as meeting the Unix specification and you could call it Unix.

    • Geoff
      November 21, 2014 at 8:51 am

      @Tom, Linux does not currently conform to the Single UNIX Specification and no Linux distro could get UNIX certification without many changes being made, some of which Linus has said he will not make, e.g. the behaviour of kill() with process ID of -1. This would mean forking the kernel to make the change - and since Linus owns the Linux trademark the resulting system could be UNIX conforming but would probably not be allowed to be called Linux.

  10. Joe
    November 19, 2014 at 11:31 pm

    @Robert AFAIK, the Linux kernel is available under GPL 2 - which means you can tweak it any way you want to and recompile it for any specific hardware you desire. The only issue is that if you change it enough (I have no idea of the specifics), you just can't distribute it to someone else and still call it "Linux". Beyond that (unless it has changed since I last looked), there are some issues (I haven't looked into) with incorporating proprietary media software into the Linux kernel because GPL 2 doesn't allow that. GPL 3 does allow that, but I don't think Linus accepted that licese revision for the kernel.

    The biggest difference between all these versions - other than licensing/cost is that many of the programs that come with them by default are slightly different - especially in the options they support and how those options are invoked - creating software porting issues. These issues gave rise to the Posix standards which define a common subset of tools/methods that will work on all systems which support it (and most do.)

  11. Joe
    November 19, 2014 at 11:04 pm

    Let's get the facts straight. Before Linux, UNIX was not dominating anything (except the admiration of those who even knew about it and had access to it). The world at that point belonged to IBM mainframes, and, to a lesser extent, a few other companies like UNIVAC, Burroughs, and even RCA (I'm sure I'm leaving a few out.) There were also minicomputers from the the likes of DEC and Data General. AFAIK, the first UNIX was implemented on a DEC PDP 7. But outside of labs and educational institutions, minicomputers weren't dominating anything either - although some of them were very nice.

    • oll
      November 20, 2014 at 10:36 am

      Not dominating, but quite widely used.
      I'm now a Linux-only IT guy, but I began my carreer as a Unix one.

      20 years ago, there were a lot of :
      * SGI stations for graphical developper
      * HP Ux or AIX stations with Solidwords , Pro-Engineer, Catia,etc... for engineers
      * Lot of Sun servers/stations in Scientific Universities and also in companies.

      It was already a mess between these different Unices -;)

  12. Robert
    November 19, 2014 at 5:11 am

    But you forgot a few things: 1)First NetBSD/UNIX which can run on virtually any chip or device and is actually more flexible than Linux. NetBSD/UNIX back in the day showed a picture of a toaster with the slogan "Why not?" and finally did achieve running a toaster on NETBSD/UNIX. 2)BSD/UNIX the most common form of the two original Unix flavors has always been free since University of Berkley open sourced it from the beginning; unlike the AT&T /Unix which Solaris is pretty much what remains of that code. Berkley rewrote out all AT&T code to stop possible copyright claims as did Linux because Microsoft bought companies providing Linux/UNIX code. 3) Linux is dependant upon Linus Torvalds to approve all kernel changes since He wrote the kernel of Linux and gave its name. Whereas BSD is board run and changed by elected directors. 4) Finally Apple chose BSD/UNIX and morphed it into its Darwin flavor for the simple fact that at the time any Linux developers had to provide all source code to any who wished it(free source). Whereas BSD/UNIX you only cite using Berkley developed code in credits and can release or hold code as you wish. Also in UNIX you can tweak the kernel to the chip and system you are using increasing speed performance, instead of the kernel that Linus approves for everyone.

    • Christopher Wetmore
      November 19, 2014 at 1:34 pm

      The Linux kernel can be tweaked. Ubuntu has/had a utility called KernelCheck to change/remove/optimize the kernel.

      I compiled a few using that. Mostly took stuff out that didn't apply to my rig. Kernel was about a third to a quarter smaller and slightly faster, and this was just winging it, not with a guide.

    • Tomas
      November 20, 2014 at 8:46 pm

      "OS X Mavericks is free for existing Mac owners. If you own a Mac running OS X 10.6.8 or later, you just have to click the Mac App Store icon, locate OS X Mavericks (currently listed in “featured”), click “Download” and run through the particulars. No money changes hands."

      • Anonymous
        August 10, 2015 at 7:27 pm

        Yeah "free" after buying the hardware. But there "free as in beer" and "free as in liberty". Linux is closer to the second definition.

        OS X is proprietary, locked down, and you're subject to the EULA.

        Linux operates under the GPL, which states you can freely distribute, modify, and change the software yourself. The only caveat being that if you redistribute you have to provide the source code to the public.

        Having ultimate freedom is the whole point behind the Free Software movement. Open Source is a bit more nebulous, it allows for proprietary code to coexist with free software, so that companies are more comfortable distributing their software. But the goal of Open Source is still freedom. Liberty to redistribute.

        If you tried to make a copy of that "free" OS X Mavericks, and share it with your friend, out even if you changed the source code for your own personal use, that Apple EULA you agreed to would mean Apple could press legal charges and have you thrown in jail.

  13. Deezy
    November 18, 2014 at 8:23 pm

    "Mac OS X is certainly easier to set up, but once again Linux is cheaper and has plenty of open source software that you can use rather than proprietary Apple-backed solutions."

    OS X Mavericks and Yosemite are free. How much cheaper can you get?
    I run Open Source and free software on my Mac, much of which was ported over from the generous Linux community. None of this is "Apple-backed."
    (You addressed the proprietary hardware vs open-ended hardware later in the comment.)

    I am well aware that the overall cost of running Macintosh is more of a financial investement then running Linux, but to be clear.... the current OS is free.

    • kwacka
      November 20, 2014 at 11:21 am

      "OS X Mavericks and Yosemite are free. How much cheaper can you get?"

      They are? Great!

      Where can I download them to run on my Linux PC (Dual booting, of course)?

    • svim
      November 21, 2014 at 4:51 am

      When it comes to Open Source, 'free' is a long-standing and confusing word as it can mean different things depending on context. Originally (when Richard Stallman was just a little slimmer but still heavily bearded) it was referring to free as in freedom, not restricted by a proprietary license. But a lot of people only define free to be tied to cost. As this wasn't clarified in this article that kind of leaves it open to interpretation, so yeah, the past two OS X versions have been free as in no charge. But they're restricted by a proprietary license (and that damn Apple ROM) so they're definitely not free in the traditional coding sense.