The Single UNIX ® Specification, Version 2
Copyright © 1997 The Open Group

 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().

UNIX ® is a registered Trademark of The Open Group.
Copyright © 1997 The Open Group
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