Unix socket I/O primitives
#include <sys/socket.h>
ssize_t sendto(int socket, const void *message,
size_t length, int flags,
const struct sockaddr *dest_addr, size_t dest_len);
ssize_t recvfrom(int socket, void *buffer,
size_t length, int flags, struct sockaddr *address,
size_t *address_len);
int poll(struct pollfd fds[], nfds_t nfds,
int timeout);
int select(int nfds, fd_set *readfds, fd_set *writefds,
fd_set *errorfds, struct timeval *timeout);