Originally Posted by Plan9
Nobody learns "the Linux kernel" apart from kernel developers and a few of the more devoted enthusiasts. What you're talking about is POSIX (and related standards) and that's a whole other debate from any of the points raised above.
Not only are you missing the point that, at it's most fundamental base, Linux==the kernel, and the stuff on top is what constitutes distributions, but you are completely wrong that I was referring to POSIX. For one thing Windows is a posix system, still to a large extent and there are projects to try to make it 100%. What I was referring to is the most basic difference is Open Source, all the way down to kernel level. Not only is most of Linux free as in "no charge" but also free as in "freedom" to make it be and do as you wish.
Technically speaking, the reason Stallman was right that it should be called Gnu-Linux was that while the original kernel could boot up, alone it was much like the Altair that could only flash a few lights, there is little to do once you are booted. To be a full operating system, there must be means to affect the way hardware is employed, to actually run a program. The hierarchy is most commonly the Kernel, Privileged Application Layer (having direct access to hardware), together comprising the base OpSys, and the Application Layer, subject to control by the Operating System below. The GNU project provided contributions to the last two but was lacking a working kernel. At the very least this means a text editor and a command environment. Examples of these introduced into the kernel are aout, elf binaries and of course sh and bash shells. Once combined, Linux as a complete operating system was born. It can be argued that Linus's contribution was the critical one, as time proved the microkernel approach would have delayed Linux more than 14 years, but the fact remains Linus found a ready solution that provided what he lacked, with GNU, and could employ it because it was not proprietary.
I'm quite sure this is not news to you, Plan9, as I feel pretty confident you have launched "make menuconfig&&make bzImage&&make modules&&make modules_install" more than once or twice
So surely you are aware of the distinctions between the kernel, an operating system, and a distribution. You are also familiar with the difference between Proprietary and Open Source, and maybe even read "The Cathedral and the Bazaar" so I'm guessing being contrary is just in your nature.