poll(5)                                                             poll(5)

NAME
     poll - definitions for the poll() function

SYNOPSIS
     #include <poll.h>

DESCRIPTION
     The <poll.h> header defines the pollfd structure that includes at
     least the following member:

     int        fd            The following descriptor being polled.

     short int  events        The input event flags (see below).

     short int  revents       The output event flags (see below).

     The <poll.h> header defines the following type through typedef:

     nfdst    An unsigned integral type used for the number of file
               descriptors.

     The following symbolic constants are defined, zero or more of which
     may be OR-ed together to form the events or revents members in the
     pollfd structure:

     POLLIN              Same effect as POLLRDNORM | POLLRDBAND.

     POLLRDNORM          Data on priority band 0 may be read.

     POLLRDBAND          Data on priority bands greater than 0 may be read.

     POLLPRI             High priority data may be read.

     POLLOUT             Same value as POLLWRNORM.

     POLLWRNORM          Data on priority band 0 may be written.

     POLLERR             An error has occurred (revents only).

     POLLHUP             Device has been disconnected (revents only).

     POLLNVAL            Invalid fd member (revents only).

     The <poll.h> header declares the following function which may also be
     defined as a macro:

     int  poll(struct pollfd fds[], nfdst nfds, int timeout);

SEE ALSO
     poll(2).





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