FD_CLR, FD_ISSET, FD_SET, FD_ZERO - macros for synchronous I/O multiplexing

Syntax	#include <sys/time.h> FD_CLR (int fd, fd_set *fdset); FD_ISSET (int fd, fd_set *fdset); FD_SET (int fd, fd_set *fdset); FD_ZERO (fd_set *fdset);
Description	See select().