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<poll.h>(P) POSIX Programmer's Manual <poll.h>(P)
poll.h - definitions for the poll() function
The <poll.h> header shall define the pollfd structure that includes at least the following
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 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 envi-
ronments 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.
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 only).
Device has been disconnected ( revents only).
Invalid fd member ( revents only).
The significance and semantics of normal, priority, and high-priority data are file and
The following shall be declared as a function and may also be defined as a macro. A func-
tion prototype shall be provided.
int poll(struct pollfd, nfds_t, int);
The following sections are informative.
The System Interfaces volume of IEEE Std 1003.1-2001, confstr(), poll(), the Shell and
Utilities volume of IEEE Std 1003.1-2001, getconf
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 orig-
inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .
IEEE/The Open Group 2003 <poll.h>(P)
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