NAME

poll.h - 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:

nfds_t

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.

POLLWRBAND

Data on priority bands greater than 0 may be written. This event only examines bands that have been written to at least once.

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. Function prototypes must be provided for use with an ISO C compiler.

int   poll(struct pollfd[], nfds_t, int);

 APPLICATION USAGE

None.

 FUTURE DIRECTIONS

None.

 SEE ALSO

poll().