1sys_time.h(0P)             POSIX Programmer's Manual            sys_time.h(0P)
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PROLOG

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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NAME

13       sys/time.h — time types
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SYNOPSIS

16       #include <sys/time.h>
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DESCRIPTION

19       The <sys/time.h> header shall define the timeval structure, which shall
20       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/time.h>  header  shall  define the itimerval structure, which
26       shall include at least the following members:
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28           struct timeval it_interval Timer interval.
29           struct timeval it_value    Current value.
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31       The <sys/time.h> header shall define the time_t and  suseconds_t  types
32       as described in <sys/types.h>.
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34       The  <sys/time.h>  header  shall define the fd_set type as described in
35       <sys/select.h>.
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37       The <sys/time.h> header shall define the following  symbolic  constants
38       for the which argument of getitimer() and setitimer():
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40       ITIMER_REAL   Decrements in real time.
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42       ITIMER_VIRTUAL
43                     Decrements in process virtual time.
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45       ITIMER_PROF   Decrements both in process virtual time and when the sys‐
46                     tem is running on behalf of the process.
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48       The <sys/time.h> header shall define  the  following  as  described  in
49       <sys/select.h>: FD_CLR() FD_ISSET() FD_SET() FD_ZERO() FD_SETSIZE
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51       The following shall be declared as functions and may also be defined as
52       macros. Function prototypes shall be provided.
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54           int   getitimer(int, struct itimerval *);
55           int   gettimeofday(struct timeval *restrict, void *restrict);
56           int   setitimer(int, const struct itimerval *restrict,
57                     struct itimerval *restrict);
58           int   select(int, fd_set *restrict, fd_set *restrict, fd_set *restrict,
59                     struct timeval *restrict);
60           int   utimes(const char *, const struct timeval [2]);
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62       Inclusion of the <sys/time.h> header may make visible all symbols  from
63       the <sys/select.h> header.
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65       The following sections are informative.
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APPLICATION USAGE

68       None.
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RATIONALE

71       None.
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FUTURE DIRECTIONS

74       None.
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SEE ALSO

77       <sys_select.h>, <sys_types.h>
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79       The  System Interfaces volume of POSIX.1‐2008, futimens(), getitimer(),
80       gettimeofday(), pselect()
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83       Portions of this text are reprinted and reproduced in  electronic  form
84       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
85       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
86       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
87       cal and Electronics Engineers,  Inc  and  The  Open  Group.   (This  is
88       POSIX.1-2008  with  the  2013  Technical Corrigendum 1 applied.) 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.unix.org/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                  2013                       sys_time.h(0P)
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