1poll.h(0P)                 POSIX Programmer's Manual                poll.h(0P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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NAME

13       poll.h — definitions for the poll() function
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SYNOPSIS

16       #include <poll.h>
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DESCRIPTION

19       The <poll.h> header shall define  the  pollfd  structure,  which  shall
20       include at least the following members:
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22           int    fd       The following descriptor being polled.
23           short  events   The input event flags (see below).
24           short  revents  The output event flags (see below).
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26       The <poll.h> header shall define the following type through typedef:
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28       nfds_t        An  unsigned  integer  type  used  for the number of file
29                     descriptors.
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31       The implementation shall support one or more  programming  environments
32       in which the width of nfds_t is no greater than the width of type long.
33       The names of these programming environments can be obtained  using  the
34       confstr() function or the getconf utility.
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36       The <poll.h> header shall define the following symbolic constants, zero
37       or more of which may be OR'ed together to form the  events  or  revents
38       members in the pollfd structure:
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40       POLLIN        Data  other  than  high-priority data may be read without
41                     blocking.
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43       POLLRDNORM    Normal data may be read without blocking.
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45       POLLRDBAND    Priority data may be read without blocking.
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47       POLLPRI       High priority data may be read without blocking.
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49       POLLOUT       Normal data may be written without blocking.
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51       POLLWRNORM    Equivalent to POLLOUT.
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53       POLLWRBAND    Priority data may be written.
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55       POLLERR       An error has occurred (revents only).
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57       POLLHUP       Device has been disconnected (revents only).
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59       POLLNVAL      Invalid fd member (revents only).
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61       The significance and semantics of normal, priority,  and  high-priority
62       data are file and device-specific.
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64       The  following  shall be declared as a function and may also be defined
65       as a macro. A function prototype shall be provided.
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67           int   poll(struct pollfd [], nfds_t, int);
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69       The following sections are informative.
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APPLICATION USAGE

72       None.
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RATIONALE

75       None.
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FUTURE DIRECTIONS

78       None.
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SEE ALSO

81       The System Interfaces volume of POSIX.1‐2008, confstr(), poll()
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83       The Shell and Utilities volume of POSIX.1‐2008, getconf
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86       Portions of this text are reprinted and reproduced in  electronic  form
87       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
88       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
89       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
90       cal and Electronics Engineers,  Inc  and  The  Open  Group.   (This  is
91       POSIX.1-2008  with  the  2013  Technical Corrigendum 1 applied.) In the
92       event of any discrepancy between this version and the original IEEE and
93       The  Open Group Standard, the original IEEE and The Open Group Standard
94       is the referee document. The original Standard can be  obtained  online
95       at http://www.unix.org/online.html .
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97       Any  typographical  or  formatting  errors that appear in this page are
98       most likely to have been introduced during the conversion of the source
99       files  to  man page format. To report such errors, see https://www.ker‐
100       nel.org/doc/man-pages/reporting_bugs.html .
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104IEEE/The Open Group                  2013                           poll.h(0P)
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