On 10/14/19, Caipenghui &lt;Caipenghui_c(a)163.com&gt; wrote: I don't think conventional Unix (SysV/BSD/Linux) has aged very well at all. As far as I'm concerned, all "modern" conventional Unices are basically cargo cult Unix at this point (especially Linux, but I'd also say it's true of current BSD and SysV). They're just carrying forward the architecture of late-70s research Unix without really understanding the design philosophy. The conventional Unix architecture was fine on a PDP-11, but it doesn't scale well to larger, more complex systems. A modern OS should be designed with security and extensibility in mind. That being said, I believe it is still possible to write a truly modern OS that is Unix-like and compatible with programs written for conventional Unix while still being secure and extensible. That's what I'm doing with the OS I'm writing <https://gitlab.com/uxrt>. It will be a thoroughly modern OS that will take the Unix philosophy further than it's ever been taken before (even further than Plan 9 does) and will be binary compatible with Linux.