ultrix man page for settimeofday

gettimeofday(2) 						System Calls Manual						   gettimeofday(2)

Name
       gettimeofday, settimeofday - get or set date and time

Syntax
       #include <sys/time.h>

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

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

Description
       The  system  call returns the system's notion of the current Greenwich time and the current time zone.  Time returned is expressed relative
       in seconds and microseconds since midnight January 1, 1970.

       The structures pointed to by tp and tzp are defined in <sys/time.h> as:

       struct timeval {
	    long tv_sec;	/* seconds since Jan. 1, 1970 */
	    long tv_usec;  /* and microseconds */
       };

       struct timezone {
	    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 of time westward from Greenwich), and a flag  that,  if  nonzero,
       indicates that Daylight Saving time applies locally during the appropriate part of the year.

       Only the superuser can set the time of day.

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

Diagnostics
       The call fails under the following conditions:

       [EFAULT]       An argument address referenced invalid memory.

       [EPERM]	      A user other than the superuser attempted to set the time.

See Also
       date(1), stime(2), ctime(3)

																   gettimeofday(2)