it may be posix-like, but even Linux is not really a POSIX OS except for one version of Red Hat long ago, and maybe now or in the future some Oracle distributio

it may be posix-like, but even Linux is not really a POSIX OS except for one version of Red Hat long ago, and maybe now or in the future some Oracle distribution. Same goes for UNIX - these proprietary, commercial certifications only apply to a frozen codebase.