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GETTIMEOFDAY(2)               System Calls Manual              GETTIMEOFDAY(2)



NAME
       gettimeofday, settimeofday - get or set the date and time

SYNOPSIS
       #include <&lt;sys/time.h>&gt;

       int gettimeofday(tp, tzp)
       struct timeval *tp;
       struct timezone *tzp;

       int settimeofday(tp, tzp)
       struct timeval *tp;
       struct timezone *tzp;

DESCRIPTION
       The  system's notion of the current Greenwich time and the current time
       zone is obtained with the gettimeofday() call, and set  with  the  set-
       timeofday() call.  The current time is expressed in elapsed seconds and
       microseconds since 00:00 GMT, January 1, 1970 (zero hour).  The resolu-
       tion of the system clock is hardware dependent; the time may be updated
       continuously, or in "ticks."

       tp points to a timeval structure, which includes the following members:

              long tv_sec;  /* seconds since Jan. 1, 1970 */
              long tv_usec; /* and microseconds */

       If tp is a NULL pointer, the current time information is  not  returned
       or set.

       tzp points to a timezone() structure, which includes the following mem-
       bers:

              int tz_minuteswest; /* of Greenwich */
              int tz_dsttime;     /* type of dst correction to apply */

       The timezone() structure indicates the local  time  zone  (measured  in
       minutes westward from Greenwich), and a flag that indicates the type of
       Daylight Saving Time correction to apply.  Note:  this  flag  does  not
       indicate whether Daylight Saving Time is currently in effect.

       Also  note  that  the offset of the local time zone from GMT may change
       over time, as may the rules for Daylight Saving Time  correction.   The
       localtime()  routine  (see  ctime(3V))  obtains this information from a
       file rather than from gettimeofday().  Programs should use  localtime()
       to  convert  dates  and times; the timezone() structure is filled in by
       gettimeofday() for backward compatibility with existing programs.

       The flag indicating the type of Daylight Saving Time correction  should
       have one of the following values (as defined in <&lt;sys/time.h>&gt;):

              0      DST_NONE: Daylight Savings Time not observed
              1      DST_USA: United States DST
              2      DST_AUST: Australian DST
              3      DST_WET: Western European DST
              4      DST_MET: Middle European DST
              5      DST_EET: Eastern European DST
              6      DST_CAN: Canadian DST
              7      DST_GB: Great Britain and Eire DST
              8      DST_RUM: Rumanian DST
              9      DST_TUR: Turkish DST
              10     DST_AUSTALT: Australian-style DST with shift in 1986

       If  tzp is a NULL pointer, the time zone information is not returned or
       set.

       Only the super-user may set the time of day or the time zone.

RETURN VALUES
       gettimeofday() returns:

       0      on success.

       -1     on failure and sets errno to indicate the error.

ERRORS
       EFAULT         An argument address referenced invalid memory.

       EPERM          A user other than the super-user attempted  to  set  the
                      time or time zone.

SEE ALSO
       date(1V), adjtime(2), ctime(3V)

BUGS
       Time  is never correct enough to believe the microsecond values.  There
       should a mechanism by which, at least, local clusters of systems  might
       synchronize their clocks to millisecond granularity.



                                21 January 1990                GETTIMEOFDAY(2)