adjtime(2)                                                       adjtime(2)


   NAME
         adjtime - correct the time to allow synchronization of the system
         clock

   SYNOPSIS
         #include <sys/time.h>

         int adjtime(struct timeval *delta, struct timeval *olddelta);

   DESCRIPTION
         adjtime adjusts the system's notion of the current time, as returned
         by gettimeofday(3C), advancing or retarding it by the amount of time
         specified in the struct timeval pointed to by delta.

         The adjustment is effected by speeding up (if that amount of time is
         positive) or slowing down (if that amount of time is negative) the
         system's clock by some small percentage, generally a fraction of one
         percent.  Thus, the time is always a monotonically increasing
         function.  A time correction from an earlier call to adjtime may not
         be finished when adjtime is called again.  If delta is 0, then
         olddelta returns the status of the effects of the previous adjtime
         call and there is no effect on the time correction as a result of
         this call.  If olddelta is not a NULL pointer, then the structure it
         points to will contain, upon return, the number of seconds and/or
         microseconds still to be corrected from the earlier call.  If
         olddelta is a NULL pointer, the corresponding information will not be
         returned.

         This call may be used in time servers that synchronize the clocks of
         computers in a local area network.  Such time servers would slow down
         the clocks of some machines and speed up the clocks of others to
         bring them to the average network time.

         Only the super-user may adjust the time of day.

         The adjustment value will be silently rounded to the resolution of
         the system clock.

   RETURN
         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.

   ERRORS
         The following error codes may be set in errno:

         EFAULT              delta or olddelta points outside the process's
                             allocated address space, or olddelta points to a
                             region of the process' allocated address space
                             that is not writable.



   7/91                                                                 Page 1

   adjtime(2)                                                       adjtime(2)


         EPERM               The process's effective user ID is not that of
                             the super-user.

   SEE ALSO
         gettimeofday(3C).
         date(1) in the User's Reference Manual.















































   Page 2                                                                 7/91