> Would this make Linux the first *NIX-based OS that is written in a language other than C? At least, with high usage...
It depends, but it's certainly not the first POSIX implementation in some high level language other than C. For example:
* Real-Time Executive for Multiprocessor Systems (RTEMS) is a real-time operating system (RTOS) designed for embedded systems. While it's often compiled down to as slim-as-possible it does support POSIX, and it's written in Ada. It's been used in a lot of projects, but because it's really an RTOS, RTEMS is typically embedded within dedicated systems and not something you'd normally interact with directly. https://en.wikipedia.org/wiki/RTEMS
* The BiiN system had an operating system written in Ada, and I think it implemented most of POSIX. However, the BiiN hardware never sold well, so it disappeared. I can't even find much about it on the web.
* BeOS implemented a lot of POSIX, and it was mostly C++. Haiku re-implements much of BeOS and is also written mostly in C++.
If you don't qualify it with "high usage", redox is that. There's also a semantic question; is Linux with some drivers done in Rust really an OS written in a language other than C? It's not like they intend to replace all the existing C with Rust.
"In 1969, Ken Thompson wrote the first UNIX system in assembly language on a PDP-7..." [1]
Half a century ago this living legend wrote an operating system. Can you imagine how much experience this single person holds today? It must be hard for him not to roll his eyes when talking to juniors.
Writing an operating system is not all that hard–thousands of undergraduates do so yearly. What's hard is coming up with UNIX and implementing it as something that others can use.
Following a tutorial with thousands of Github repos to look at from the comfort of you favorite operating system isn't even remotely comparable to writing Unix in 1969.
Those undergraduates do so with development tools that had hundreds of thousands of man-hours invested into them. We can't pretend like this doesn't make their job any easier.
> "Please note that the Rust support is intended to enable writing drivers and similar "leaf" modules in Rust, at least for the foreseeable future. In particular, we do not intend to rewrite the kernel core nor the major kernel subsystems (e.g. `kernel/`, `mm/`, `sched/`...). Instead, the Rust support is built on top of those."
