adjtime(2)                       UNIX System V                       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.

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



10/89                                                                    Page 1

adjtime(2)                       UNIX System V                       adjtime(2)


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



















































Page 2                                                                    10/89