NAME
select, FD_CLR, FD_ISSET, FD_SET, FD_ZERO - synchronous I/O
multiplexing
SYNOPSIS
#include <sys/select.h>
int select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *errorfds, struct timeval *timeout)
void FD_CLR(int fd, fd_set *fdset)
int FD_ISSET(int fd, fd_set *fdset)
void FD_SET(int fd, fd_set *fdset)
void FD_ZERO(fd_set *fdset)
DESCRIPTION
Select examines the file descriptors given in the sets
readfds, writefds, and errorfds, up to and including file
descriptor nfds-1 , for reading, writing, or exceptional
conditions, respectively. Select currently supports regular
files, pipes, named pipes, inet, and tty file descriptors
(including pty).
If the readfds argument is not a null pointer, it points to
an object of type fd_set that on input specifies the file
descriptors to be checked for being ready to read, and on
output indicates which file descriptors are ready to read.
Writefds and errorfds have an analogous meaning for file
descriptors to be checked for being ready to read, respec-
tively have pending exceptional (error) conditions.