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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.
NAME
       poll.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)