poll.h

<poll.h>(P)							  <poll.h>(P)



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  block-
	      ing.

       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,	 get-
       conf

COPYRIGHT
       Portions	 of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2003 Edition, Standard for Information  Technol-
       ogy  --	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 .



POSIX				     2003			  <poll.h>(P)