gettimeofday

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NAME

       gettimeofday, settimeofday - get / set time


SYNOPSIS

       #include <sys/time.h>
       #include <unistd.h>

       int gettimeofday(struct timeval *tv, struct timezone *tz);
       int settimeofday(const struct timeval *tv ,  const  struct
       timezone *tz);


DESCRIPTION

       gettimeofday  and settimeofday can set the time as well as
       a timezone.  tv is a  timeval  struct,  as  specified   in
       /usr/include/sys/time.h:

       struct timeval {
                      long tv_sec;        /* seconds */
                      long tv_usec;  /* microseconds */
                      };


       and tz is a timezone :

       struct timezone {
                       int  tz_minuteswest;
                       /* minutes west of Greenwich */
                       int  tz_dsttime;
                       /* type of dst correction */
                       };

       With daylight savings times defined as follows :

       DST_NONE /* not on dst */
       DST_USA    /* USA style dst */
       DST_AUST   /* Australian style dst */
       DST_WET /* Western European dst */
       DST_MET /* Middle European dst */
       DST_EET /* Eastern European dst */
       DST_CAN /* Canada */
       DST_GB     /* Great Britain and Eire */
       DST_RUM /* Rumania */
       DST_TUR /* Turkey */
       DST_AUSTALT     /* Australian style with shift in 1986 */

       And the following macros are defined to operate on this :
       #define   timerisset(tvp)\
                  ((tvp)->tv_sec || (tvp)->tv_usec)
       #define   timercmp(tvp, uvp, cmp)\
                  ((tvp)->tv_sec cmp (uvp)->tv_sec ||\
                  (tvp)->tv_sec == (uvp)->tv_sec &&\
                  (tvp)->tv_usec cmp (uvp)->tv_usec)
          #define timerclear(tvp)
                  ((tvp)->tv_sec = (tvp)->tv_usec = 0)

       If either tv or tz is null, the corresponding structure is
       not set or returned.

       Only the super user may use settimeofday.


ERRORS

       EPERM  settimeofday is called by someone  other  than  the
              superuser.

       EINVAL Timezone (or something else) is invalid.


CONFORMING TO

       BSD 4.3


SEE ALSO

       date(1), adjtimex(2), time(2), ctime(3), ftime(3)
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