POLL.H(3HEAD) Headers POLL.H(3HEAD)

NAME

poll.h, poll - definitions for the poll() function

SYNOPSIS

#include <poll.h>

DESCRIPTION

The <poll.h> header defines the pollfd structure, which includes the
following members:

int fd
the following descriptor being polled


short events
the input event flags (see below)


short revents
the output event flags (see below)


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

nfds_t
an unsigned integer type used for the number of file
descriptors


The implementation supports one or more programming environments in
which the width of nfds_t is no greater than the width of type long.
The names of these programming environments can be obtained using the
confstr() function or the getconf utility. See confstr(3C) and
getconf(1).


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

POLLIN
Data other than high-priority data can be read without
blocking.


POLLRDNORM
Normal data can be read without blocking.


POLLRDBAND
Priority data can be read without blocking.


POLLPRI
High priority data can be read without blocking.


POLLOUT
Normal data can be written without blocking.


POLLWRNORM
Equivalent to POLLOUT.


POLLWRBAND
Priority data can be written.


POLLERR
An error has occurred (revents only).


POLLHUP
Device has been disconnected (revents only).


POLLNVAL
Invalid fd member (revents only).


The significance and semantics of normal, priority, and high-priority
data are file and device-specific.

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Standard |
+--------------------+-----------------+

SEE ALSO

getconf(1), poll(2), confstr(3C), attributes(7), standards(7)

September 9, 2004 POLL.H(3HEAD)