Dear all, I have these files, common.h: #include <sys/types.h> #include <sys/stat.h> #include <unistd.h> ... print.h: #include "common.h" ... print.c: ... ...S_IFMT... ... It compiles fine on my Mac, while ERROR! on linux-lab: error: ‘S_IFMT’ undeclared (first use in this function) Could anyone tell my why please... Sincerely, Kai