poll.h(0P) POSIX Programmer's Manual poll.h(0P)PROLOG
This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the corresponding
Linux manual page for details of Linux behavior), or the interface may
not be implemented on Linux.
NAMEpoll.h — definitions for the poll() function
SYNOPSIS
#include <poll.h>
DESCRIPTION
The <poll.h> header shall define the pollfd structure, which shall
include at least 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 shall define the following type through typedef:
nfds_t An unsigned integer type used for the number of file
descriptors.
The implementation shall support 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.
The <poll.h> header shall define the following symbolic constants, zero
or more of which may be OR'ed together to form the events or revents
members in the pollfd structure:
POLLIN Data other than high-priority data may be read without
blocking.
POLLRDNORM Normal data may be read without blocking.
POLLRDBAND Priority data may be read without blocking.
POLLPRI High priority data may be read without blocking.
POLLOUT Normal data may be written without blocking.
POLLWRNORM Equivalent to POLLOUT.
POLLWRBAND Priority data may 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.
The following shall be declared as a function and may also be defined
as a macro. A function prototype shall be provided.
int poll(struct pollfd [], nfds_t, int);
The following sections are informative.
APPLICATION USAGE
None.
RATIONALE
None.
FUTURE DIRECTIONS
None.
SEE ALSO
The System Interfaces volume of POSIX.1‐2008, confstr(), poll()
The Shell and Utilities volume of POSIX.1‐2008, getconf
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
cal and Electronics Engineers, Inc and The Open Group. (This is
POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the source
files to man page format. To report such errors, see https://www.ker‐
nel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2013 poll.h(0P)