> Actually, Mac OS is Linux...
Actually, NO IT'S NOT. Emphatically not.
MacOS is based on FreeBSD Unix, not Linux. Completely different at all levels except "work-similar".
The Linux kernel was written as a "work-alike" for Unix in the early 90's, but that kernel and the BSD Unix kernel are completely different "under the hood". The system libraries of Linux and BSD are likewise completely different, even though they implement similar functionality.
Both BSD and Linux make extensive use of the Gnu operating system sources (utilities, tools, etc.) and thus have many command-line commands in common. However, they are alike only at the source-code level -- their running programs (executables) are not at all cross-compatible.
Ping to #142 above.