Section: POSIX Programmer's Manual (0P)
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.
--- definitions for the poll() function
header shall define the
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).
header shall define the following type through
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
is no greater than the width of type
The names of these programming environments can be obtained using the
function or the
header shall define the following symbolic constants, zero or more of
which may be OR'ed together to form the
members in the
Data other than high-priority data may be read without blocking.
Normal data may be read without blocking.
Priority data may be read without blocking.
High priority data may be read without blocking.
Normal data may be written without blocking.
Equivalent to POLLOUT.
Priority data may be written.
An error has occurred (revents
Device has been disconnected (revents
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.
The System Interfaces volume of POSIX.1-2017,
The Shell and Utilities volume of POSIX.1-2017,
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
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