[hylaride]

It's a shame. NT did support POSIX, but it was in practice designed to make it easier to port UNIX apps. At co-op job I had back in the day (~2000), I had to fight with Veritas' backup software on NT that wrote to tapes. I don't recall what it was (a device mapping to the drive maybe?), but you could see the UNIX foundations of the software.

[pjmlp]

Ironically they had multiple iterations of it, with POSIX subsystem in NT, MKS Toolkit, Interix, Windows Services for UNIX, for various levels of "POSIX support", dropped everything on Windows Vista, only to create WSL out from Project Astoria ashes.

And before they got golden goose with MS-DOS/IBM deal, they were into the UNIX business with Xenix.

A few reasons why Linux would probably never taken off, had Microsoft stayed closer to their UNIX related projects.

[hylaride]

I think Linux took off due to cost. If you're a startup or a web company with razor thin margins, you're not going to go Microsoft (or Sun).

Same story with MySQL.

[temac]

There was actually "SUA" after "SFU", only removed in Windows 8.1 and Windows Server 2012 R2.

[banish-m4]

It was mostly for running NFS to talk to other UNIX boxes, not to run UNIX software.

To make a Windows NT box UNIX-ish, there was MKS Toolkit. It predates Cygwin, msys, and djgpp.