How closely are Mac OS X and BSD related?

Question

I read that Mac OS X and bsd are related. How closely are they related. Can Mac OS X software be tweaked and installed on BSD?

Answer 1

It depends on what kinds of apps you are trying to port. If you write POSIX-compatible C/C++ console programs, they will compile and work just fine under any POSIX-compatible system (mostly Linux and BSD flavors), but note that OS X often doesn't implement the newest POSIX functions (e.g. utimensat) which are available in Linux. On the other hand, graphical applications use Cocoa or the older Carbon, which would require GNUstep. Porting graphical applications is quite uncommon because every graphical environment has different design standards and conventions, so graphical applications usually have to be written from scratch for each graphical environment.