1GETTIMEOFDAY(2)               System Calls Manual              GETTIMEOFDAY(2)
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NAME

6       gettimeofday, settimeofday - get/set date and time
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SYNOPSIS

9       #include <sys/time.h>
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11       gettimeofday(tp, tzp)
12       struct timeval *tp;
13       struct timezone *tzp;
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15       settimeofday(tp, tzp)
16       struct timeval *tp;
17       struct timezone *tzp;
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DESCRIPTION

20       The  system's notion of the current Greenwich time and the current time
21       zone is obtained with the gettimeofday call, and set with the  settime‐
22       ofday  call.   The  time is expressed in seconds and microseconds since
23       midnight (0 hour), January 1, 1970.  The resolution of the system clock
24       is  hardware  dependent, and the time may be updated continuously or in
25       ``ticks.''  If tzp is zero, the  time  zone  information  will  not  be
26       returned or set.
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28       The structures pointed to by tp and tzp are defined in <sys/time.h> as:
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30              struct timeval {
31                   long tv_sec;        /* seconds since Jan. 1, 1970 */
32                   long tv_usec;       /* and microseconds */
33              };
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35              struct timezone {
36                   int  tz_minuteswest;     /* of Greenwich */
37                   int  tz_dsttime;    /* type of dst correction to apply */
38              };
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40       The  timezone structure indicates the local time zone (measured in min‐
41       utes of time westward from Greenwich), and a  flag  that,  if  nonzero,
42       indicates  that  Daylight Saving time applies locally during the appro‐
43       priate part of the year.
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45       Only the super-user may set the time of day or time zone.
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RETURN

48       A 0 return value indicates that the call succeeded.  A -1 return  value
49       indicates  an  error occurred, and in this case an error code is stored
50       into the global variable errno.
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ERRORS

53       The following error codes may be set in errno:
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55       [EFAULT]       An argument address referenced invalid memory.
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57       [EPERM]        A user other than the super-user attempted  to  set  the
58                      time.
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SEE ALSO

61       date(1), adjtime(2), ctime(3), timed(8)
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654th Berkeley Distribution        May 14, 1986                  GETTIMEOFDAY(2)
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