UNIX command for replace files

Question

on Mac, you know there is no 'merge files' when you command+c/command+v some folder on another one, it actually replaces it. I'm simply wondering on what UNIX is this based? Because correct me if I'm wrong, but "cp - R" DOES merge files, no? And that's what I'm doing via the Finder, copying some files and folders...

thanks!

Answer 1

GUI functionality generally doesn't use console commands. The Finder presumably employs some Cocoa interface; the cp utility normally uses open/read/write (i.e., it reads the contents of the file into memory and creates another file using these contents elsewhere) as there is no Unix system call for copying files.