re: Microsoft: I was just joking
re: Android: When Google moves away by forking it and developing it independantly (like they dit with webkit and blink), it will still be based on Linux
re: Mac-OS: Mac-OS is based on NextStep NextStep was based on the Unix Mack kernel with added code derived from BCD. GNU/Linux is not Unix ( google GNU

), but due to the Posix standard, software written for Unix can be compiled for Linux. Many tools and scripts meant for a Linux system work easily within the macOS terminal.