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OpenSolaris 2009.06 - man page for adjtime (opensolaris section 2)

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adjtime(2)				   System Calls 			       adjtime(2)

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

       #include <sys/time.h>

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

       The adjtime() function adjusts the system's notion of the current time as returned by get-
       timeofday(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. The time is always a monotonically increasing func-
       tion. A time correction from an earlier call to adjtime() may not be  finished  when  adj-
       time() is called again.

       If  delta  is 0, then olddelta returns the status of the effects of the previous adjtime()
       call with 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 successful return, the
       number of seconds and/or microseconds still to be corrected from the earlier call. If old-
       delta 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 a processes with appropriate privileges can adjust the time of day.

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

       Upon  successful  completion, adjtime() returns 0. Otherwise, it returns -1 and sets errno
       to indicate the error.

       The adjtime() function will fail if:

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

       EINVAL	 The tv_usec member of delta is not within valid range (-1000000 to 1000000).

       EPERM	 The {PRIV_SYS_TIME} privilege is not asserted in the effective set of the  call-
		 ing process.

       Additionally, the adjtime() function will fail for 32-bit interfaces if:

       EOVERFLOW    The size of the tv_sec member of the timeval structure pointed to by olddelta
		    is too small to contain the correct number of seconds.

       date(1), gettimeofday(3C), privileges(5)

SunOS 5.11				   20 Jan 2003				       adjtime(2)
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