I thought Linux was a stand alone independent program?
Linux is a UNIX-like operating system that started life with a MINIX code base and was enhanced with lots of guidance to Linux Torvalds from people in the industry that wanted him to succeed. Source code from many UNIX versions was captured and massively cleaned up with the GNU C compiler built by Richard Stallman. It really has been a massive community effort. Thus far, separated for the social justice PC tainted behavior. If that is what is coming to the Linux open source collaboration, then all hell is likely to break loose. My customers and contracts staff have always been vary wary of open source software licenses. The threat of losing control over your software build because a key library is ripped away or restricted can turn a viable project into a dead duck.
I have been part of that community since the early 80s. One of my quiet contributions was the restructure of the internal tables used for the "zip" compression utility. When I first got the source, it wouldn't play on my big-endian machines. After restructure, it worked great on every CPU I could lay my hands on. I fed it back and the reward was the utility appeared on many more platforms in the ensuing months. That was the nature of the beast. We shared each other's work. We improved it and shared the improvements. Many of us worked for big corporations and used the open source to speed development. The corporations effectively provided a "shadow" support for the community while enjoying the benefits of the code reuse.
I did the same with David Korn on his Korn shell. I ported to 30 different platforms. When I spotted a problem, I shared it with David. He confirmed and applied the fix. That was before we had nice platforms lit "github" to share collaborative effort. E-mail was sufficient.