poll.h(0p) — Linux manual page


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

PROLOG         top

       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         top

       poll.h — definitions for the poll() function

SYNOPSIS         top

       #include <poll.h>

DESCRIPTION         top

       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

       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

       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.



RATIONALE         top




SEE ALSO         top

       The System Interfaces volume of POSIX.1‐2017, confstr(3p),

       The Shell and Utilities volume of POSIX.1‐2017, getconf(1p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 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 .

       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.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group               2017                        poll.h(0P)

Pages that refer to this page: poll(3p)