1sys_select.h(0P) POSIX Programmer's Manual sys_select.h(0P)
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6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
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12 sys/select.h — select types
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15 #include <sys/select.h>
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18 The <sys/select.h> header shall define the timeval structure, which
19 shall include at least the following members:
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22 time_t tv_sec Seconds.
23 suseconds_t tv_usec Microseconds.
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25 The <sys/select.h> header shall define the time_t and suseconds_t types
26 as described in <sys/types.h>.
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28 The <sys/select.h> header shall define the sigset_t type as described
29 in <signal.h>.
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31 The <sys/select.h> header shall define the timespec structure as
32 described in <time.h>.
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34 The <sys/select.h> header shall define the fd_set type as a structure.
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36 The <sys/select.h> header shall define the following symbolic constant,
37 which shall have a value suitable for use in #if preprocessing direc‐
38 tives:
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40 FD_SETSIZE Maximum number of file descriptors in an fd_set structure.
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42 The following shall be declared as functions, defined as macros, or
43 both. If functions are declared, function prototypes shall be provided.
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46 void FD_CLR(int, fd_set *);
47 int FD_ISSET(int, fd_set *);
48 void FD_SET(int, fd_set *);
49 void FD_ZERO(fd_set *);
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51 If implemented as macros, these may evaluate their arguments more than
52 once, so applications should ensure that the arguments they supply are
53 never expressions with side-effects.
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55 The following shall be declared as functions and may also be defined as
56 macros. Function prototypes shall be provided.
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59 int pselect(int, fd_set *restrict, fd_set *restrict, fd_set *restrict,
60 const struct timespec *restrict, const sigset_t *restrict);
61 int select(int, fd_set *restrict, fd_set *restrict, fd_set *restrict,
62 struct timeval *restrict);
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64 Inclusion of the <sys/select.h> header may make visible all symbols
65 from the headers <signal.h> and <time.h>.
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67 The following sections are informative.
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70 None.
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73 None.
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76 None.
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79 <signal.h>, <sys_time.h>, <sys_types.h>, <time.h>
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81 The System Interfaces volume of POSIX.1‐2017, pselect()
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84 Portions of this text are reprinted and reproduced in electronic form
85 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
86 table Operating System Interface (POSIX), The Open Group Base Specifi‐
87 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
88 Electrical and Electronics Engineers, Inc and The Open Group. In the
89 event of any discrepancy between this version and the original IEEE and
90 The Open Group Standard, the original IEEE and The Open Group Standard
91 is the referee document. The original Standard can be obtained online
92 at http://www.opengroup.org/unix/online.html .
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94 Any typographical or formatting errors that appear in this page are
95 most likely to have been introduced during the conversion of the source
96 files to man page format. To report such errors, see https://www.ker‐
97 nel.org/doc/man-pages/reporting_bugs.html .
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101IEEE/The Open Group 2017 sys_select.h(0P)