针对不同系统的宏定义，对于Linux而言
/* port.h - portability defines */ #elif defined(linux)
# define OS_Linux
# define ARCH "Linux" #ifdef OS_Linux
# define HAVE_DAEMON
# define HAVE_SETSID
# define HAVE_WAITPID
# define HAVE_TM_GMTOFF
# define HAVE_SENDFILE
# define HAVE_LINUX_SENDFILE
# define HAVE_SCANDIR
# define HAVE_INT64T
#endif /* OS_Linux */