What is POSIX?

[sorcerer_see]

POSIX is a standard for UNIX operating systems

POSIX approved operating systems are:

proprietary
Solaris
BSD
macOS

open source
Debian / Ububtu / Mint /  MXLinux
Red Hat /  Fedora
SUSE
ArchLinux
Android
Gentoo
OpenBSD
freeBSD
...