这是一个同样来自贝尔实验室的和UNIX有着渊源的操作系统, 其简洁的设计和实现易于我们学习和理解

				/* Local acconfig.h for autoheader.				   Descriptive text for the C preprocessor macros that				   the patch configure.in can define.				   autoheader copies the comments into config.hin.  */								/* Define if there is a member named d_ino in the struct describing				   directory headers.  */				#undef D_INO_IN_DIRENT								/* Define if memchr works.  */				#undef HAVE_MEMCHR								/* Define if `struct utimbuf' is declared -- usually in .  */				#undef HAVE_STRUCT_UTIMBUF