@david You specify the file paths in GNU bash or an inferior shell and that talks to glibc, which does readdir() internally, which at the last step communicates with a FUSE filesystem driver (running in GNUserspace) or does SYSCALLs to interface with a filesystem driver in Linux (not sure if navigating directories actually specifies the file paths with /, or passes some other data structure, although the sys_getcwd SYSCALL returns the current file path and the sys_chdir SYSCALL takes a file path).

GNU bash of course works just as well on GNU/Hurd.

That image really should say; GNU, macos DOS, windows