Linux vs. Unix: What's the difference?

Stumbled upon this nice article I think which every linux user shall know about. Was not able to resist to create a thread about it and make it a pinned one.

"Dive into the differences between these two operating systems that share much of the same heritage and many of the same goals."

*opensource.com/article/18/5/differ...t open source,agreements with its owner, AT&T
.

Well I already knew the differences. Technically Linux comes under the Unix umbrella (Linux = Linus' Unix). Just that Unix flavours are usually not GPL licensed and most of them are not open source. There are some exceptions though such as illumos (formerly Open Solaris).

Another well known Unix flavour is BSD.

Desmond David said:
Well I already knew the differences. Technically Linux comes under the Unix umbrella (Linux = Linus' Unix). Just that Unix flavours are usually not GPL licensed and most of them are not open source. There are some exceptions though such as illumos (formerly Open Solaris).

Another well known Unix flavour is BSD.

LINUX - linux is not unix.

Desmond David said:
Well I already knew the differences. Technically Linux comes under the Unix umbrella (Linux = Linus' Unix). Just that Unix flavours are usually not GPL licensed and most of them are not open source. There are some exceptions though such as illumos (formerly Open Solaris).

Another well known Unix flavour is BSD.

This article is for those who does not know and covers the difference with history on a single page. I think many are still out there wondering about the difference.

Desmond David said:
Another well known Unix flavour is BSD.

Best example of something on BSD? MacOS.

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thetechfreak said:
Best example of something on BSD? MacOS.

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Sony Playstation OSs are derived from BSD too. FreeBSD to be precise.

@Desmond David Linux is definitely not unix. It is "unix-like" to the extent that it follows some similar design principles and userland API tends to be very unix-like on most distributions. You will quickly find that to not be the case once you move out of standard GNU/Linux distros or distros that try to copy GNU coreutils completely.

There are some important things to note here though:

1. Linux is merely the kernel. When talking about unix you have to consider the operating system as a whole. So a debian or a fedora or an arch linux may or may not be unix based on their ability to comply with the posix standard and the single unix specification.
2. Linux does not aim to follow the single unix specification, and implementing even the complete POSIX set is optional for distro developers. Only one distribution that I know of complies with POSIX fully, which is a chinese OS derived from Debian. I forget the name.
3. Most unices are proprietary, and even the BSDs do not aim to completely match POSIX.
4. There is a thought that sometimes POSIX goes in contravention of operating system design.

You'll notice I bring up POSIX several times: this is because POSIX is a required standard under the single unix specification, and posix allows different system implementations to talk to each other natively. So even if the implementation changes, the behaviour remains predictable.

The current unices, per the definition of single unix specification are:

1. MacOS (but not Darwin)
2. IBM z/OS
3. IBM AIX
4. HP-UX

Even with this, only AIX meets the latest version of the spec, aka UNIX 7.

Solaris was formerly a unix system but Oracle no longer cares about maintaining the standard.

*nix is a better term for describing the various unices and unix-like operating systems in the market.

By the way, unix on the whole is irrelevant now. Linux already dominates the server and supercomputer space, and outside of esoteric uses like mainframes (which are also a dying breed) and databases (AIX), only BSD has a small general purpose following, because it is used by almost every manufacturer under the sun to avoid the legal implications of the GPL.

Stormbringer said:
Sony Playstation OSs are derived from BSD too. FreeBSD to be precise.

I wonder though how much like Windows the architecture is now for the XBOX series X and PS5, especially with features like Ray Tracing. Hardware is esentially what we have on PC's nowadays.

thetechfreak said:
I wonder though how much like Windows the architecture is now for the XBOX series X and PS5, especially with features like Ray Tracing. Hardware is esentially what we have on PC's nowadays.

If you're unfamiliar with programming you may be surprised by how similar the code is. The Xbox operating system has always been a customized version of Windows, with the Xbox 360 (IIRC) being a heavily modified Windows XP ported to a non-x86 architecture and the Xbox One OS being a somewhat customized Windows 10. Both use the NT kernel, which is the core on which every modern version of Windows is built. The UI is just a frontend which can be easily changed if you know what you are doing.

As for the Playstation (and virtually every other BSD-derived system software under the sun), the operating system is usually based on FreeBSD, with modifications and proprietary drivers for the hardware. Hell, with the Playstation 5 it's basically just modified versions of the consumer drivers distributed by AMD, and people have successfully patched drivers into custom linux installations on the PS5 hardware.

Mostly vendors only change the parts they don't like or are required to be modified for their customised software to work.

Here's another nugget: Intel embeds MINIX, another unix-like operating system, inside each and every one of their processors since the past half decade or so. It is the operating system which runs the cpu's management engine core, which is independent and "out of band" with the main system - you are unable to interact with that core directly, and your operating system is unaware of it.

Extreme Gamer said:
Hell, with the Playstation 5 it's basically just modified versions of the consumer drivers distributed by AMD, and people have successfully patched drivers into custom linux installations on the PS5 hardware.

Don't you mean PS4 here?

thetechfreak said:
I wonder though how much like Windows the architecture is now for the XBOX series X and PS5, especially with features like Ray Tracing. Hardware is esentially what we have on PC's nowadays.

Hardware wise they are more PC like these days. The difference now lies in how well they use respective graphical APIs to extract the best from the hardware.

SaiyanGoku said:
Don't you mean PS4 here?

Right, slip of mind.

Stormbringer said:
Hardware wise they are more PC like these days. The difference now lies in how well they use respective graphical APIs to extract the best from the hardware.

Eh, for Xbox the API is the same as desktop - Direct3D 12. The difference lies in driver tuning from AMD for a very specific hardware model, how microsoft exposes the resources of the xbox one to developers and also how the developers code their games and applications. For the Switch and the PS4 the API is proprietary (but designed similarly to open APIs) but it is in the interest of both Nintendo and Sony to keep the bloat as minimal as possible.

But mostly it's the coding of the game that determines performance, because gaming consoles generally offer very low level access to the system resources. Even if the system software is great and really resource-light, nothing can save a game developed by Yanderedev, if you know what I mean.