It's not just about paying for certification. You also have to replace a lot of things like ed, awk, grep, etc. with versions that are compatible with the UNIX specification. GNU utilities didn't target 100% UNIX compatibility and they have differences that mean that a command that works on UNIX might not work (or might not work the same) on a Linux distro using GNU utilities. glibc has slight differences from the spec too.

In order to get a Linux distro certified, you'd have to make changes which would make it less compatible with all the other Linux distros out there.

The reason why RedHat doesn't pay for UNIX certification is that their distros wouldn't be compliant. The reason why they don't make their distros compliant is that their customers would vastly prefer that RedHat use "standard Linux" tools than replace them with UNIX-compliant ones. Customers don't want a Linux distro that's subtly different/incompatible compared to what everyone expects in a Linux system. They'd rather it be not-UNIX.

Yes, you can modify a Linux distro to be UNIX. However, most Linux systems are not real UNIX - and you wouldn't want it to be real UNIX.

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arccy 3 days ago | parent | next [-]

this talk of GNU being "standard" is toxic, as if anything that doesn't use it is weird or off spec.

the GNU userland might be common for user facing systems, but it's nowhere close to standard.

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oguz-ismail 3 days ago | parent | next [-]

It's the de facto standard. No one knows how to use other flavors of tools like date, find, grep, sed etc.

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pjmlp 3 days ago | parent | next [-]

Some of us do, but we are old enough to know that Linux is not a synonym for UNIX, and to have installed it from floppies.

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bigyabai 3 days ago | parent [-]

For all the good that does you running modern software. "UNIX support" in a post k8s age is considered optional.

	▲	pjmlp 3 days ago \| parent \| next [-]
		Thankfully not everything needs Kubernetes. If you are going there, I also consider Kubernetes optional. When I have the option to push for specific cloud deployments, I usually push for serverless or managed containers. You might argue that still depends on Kubernetes, for me Kubernetes just like Linux, is mostly an implementation detail, that we get to open support tickets when it doesn't go as planned. No one needs to hurt themselves running a local Kubernetes cluster.
	▲	arccy 3 days ago \| parent \| prev [-]
		actually with docker and K8s we see Alpine used more and more, and that doesn't come with a GNU userland.

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stonogo 2 days ago | parent | prev [-]

There's no such thing as a "de facto standard." The whole point of a standard is to be the jure that the thing is de. The word you're looking for is "common."

	▲	oguz-ismail 2 days ago \| parent [-]
		https://en.wikipedia.org/wiki/De_facto_standard

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quotemstr 3 days ago | parent | prev [-]

GNU utilities won. That's just reality.

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dwheeler 3 days ago | parent | prev [-]

Citation needed.

I'm not sure what you mean by "Unix specification". But if you mean the international standard POSIX, yes, people care. Red Hat routinely participates in POSIX spec revision.

There are a very few deviations where you have to enable "POSIXLY_CORRECT". If that's what you mean, then you can turn that on. But in every area that matters, Linux distros implement the POSIX spec by default, and you can even turn on the POSIXLY_CORRECT mode to exactly follow it. They extend beyond it, but that is allowed and expected.

The people who build the tools in Linux distros care a lot. I know the implementors of dash and GNU make routinely refer to POSIX. The Linux distros don't have to as much with POSIX because that is generally a conpleted work and it's the maintainers of the tools who must address the updates to POSIX.

	▲	mdasen 3 days ago \| parent \| next [-]
		The UNIX specification is not the same as POSIX: https://en.wikipedia.org/wiki/Single_UNIX_Specification. You might say "their exact view of what UNIX is isn't important and POSIX is," but POSIX is not the UNIX spec. You might think the Unix spec isn't important - and it really isn't today. Linux generally targets what is important and what users care about - and that isn't the UNIX spec. It is often the same as the UNIX spec, but not always and there are deviations.
	▲	swiftcoder 3 days ago \| parent \| prev [-]
		Posix is a subset of the Unix standard - it's necessary, but not sufficient to pass Unix certification.