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<poll.h>(0P)               POSIX Programmer's Manual              <poll.h>(0P)

NAME
       poll.h - definitions for the poll() function
SYNOPSIS
       #include <poll.h>
DESCRIPTION
       The  <poll.h> header shall define the pollfd structure that includes 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  descrip-
              tors.

       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 following symbolic constants shall be  defined,  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  IEEE Std 1003.1-2001,   confstr(),
       poll(), the Shell and Utilities volume of IEEE Std 1003.1-2001, getconf
COPYRIGHT
       Portions  of  this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
       Electrical  and  Electronics  Engineers, Inc and The Open Group. 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.opengroup.org/unix/online.html .

IEEE/The Open Group                  2003                         <poll.h>(0P)