select() (Wang, 12.14)
Usage:
#include <sys/time.h>
#include <sys/types.h>
int select( int nfds,
fd_set *readfds,
fd_set *writefds,
fd_set *exceptfds,
struct timeval *timeout );
where the three fd_set variables are file descriptor masks
fd_set is defined in <sys/select.h>, which is included by <sys/types.h>