09-07-2010
1. select returns > 0 if there are available sockets
2. FD_ISSET(sock, &writefds) returns true if sock is in the FDSET and the sock descriptor is ready to write. sock is an integer and is one of the sockets you intend to write.
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LEARN ABOUT MOJAVE
pselect
PSELECT(2) BSD System Calls Manual PSELECT(2)
NAME
pselect -- synchronous I/O multiplexing a la POSIX.1g
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <sys/select.h>
int
pselect(int nfds, fd_set *restrict readfds, fd_set *restrict writefds, fd_set *restrict errorfds, const struct timespec *restrict timeout,
const sigset_t *restrict sigmask);
DESCRIPTION
The pselect() function was introduced by IEEE Std 1003.1g-2000 (``POSIX.1'') as a slightly stronger version of select(2). The nfds, readfds,
writefds, and errorfds arguments are all identical to the analogous arguments of select(). The timeout argument in pselect() points to a
const struct timespec, rather than the (modifiable) struct timeval used by select(); as in select(), a null pointer may be passed to indicate
that pselect() should wait indefinitely. Finally, sigmask specifies a signal mask which is set while waiting for input. When pselect()
returns, the original signal mask is restored.
See select(2) for a more detailed discussion of the semantics of this interface, and for macros used to manipulate the fd_set data type.
RETURN VALUES
The pselect() function returns the same values and under the same conditions as select().
ERRORS
The pselect() function may fail for any of the reasons documented for select(2) and (if a signal mask is provided) sigprocmask(2).
SEE ALSO
kqueue(2), poll(2), select(2), sigprocmask(2)
STANDARDS
The pselect() function conforms to IEEE Std 1003.1-2001 (``POSIX.1'').
HISTORY
The pselect() function first appeared in FreeBSD 5.0.
AUTHORS
The pselect() manual page was written by Garrett Wollman <wollman@FreeBSD.org>.
BSD
June 16, 2002 BSD