hpux man page for adjtime

adjtime(2)							System Calls Manual							adjtime(2)

NAME
       adjtime() - correct the time to synchronize the system clock

SYNOPSIS
DESCRIPTION
       The  function  adjusts  the  current  time  of  the system.  The time is either advanced or retarded by the amount of time specified in the
       pointed to by delta.

       The adjustment is made by applying small correctional adjustments to the value of current time that the system keeps.  The time	is  always
       increasing monotonically, but at a rate slightly slower or faster than normal.

       A  time	correction for an earlier call to may not be complete when is called.  The second call to stops the first call to if delta is non-
       NULL, but does not undo the effects of the previous call.  If delta is NULL, then no time correction will be done.

       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.

       The  call  to  returns immediately, though its effect will continue until the whole correction is made or until modified by another call to
       either with a non-NULL delta or to change the system time (see

       Only a user with appropriate privileges can call successfully with a non-NULL delta.  Any user can call with a NULL  delta  to  report  the
       correction left from the previous call.

   Limits
       is defined in as having at least 2 members, tv_sec (seconds) and tv_usec (microseconds).

       When  is called, if the delta.tv_sec field is greater than 31536000 (approx. 365 days), or less than -31536000, then fails with an errno of
       The tv_usec field is not used in the calculations to determine the limits, and so the actual limits on adjustments are seconds.

       Note that the desired seconds may be negative.  Since the type of the tv_sec field is (unsigned long), any negative values for tv_sec  need
       to be cast.

       Any olddelta value returned by the function will be returned such that the signs of non-zero members are the same.

   Interaction with Other System Calls
       A  call	to change the system time terminates the correction currently in effect.  A subsequent call to will return {0, 0} for the olddelta
       parameter.  This includes system calls such as and

   Security Restrictions
       This system call requires the privilege in order to successfully usa a non-NULL delta.  Processes owned by the superuser have  this  privi-
       lege.   Processes  owned by other users may have this privilege, depending on system configuration.  See privileges(5) for more information
       about privileged access on systems that support fine-grained privileges.

RETURN VALUE
       Upon successful completion, returns a value of 0; otherwise, it returns a value -1 and sets to indicate the error.

ERRORS
       fails if one or more of the following is true:

	      if the process does not have the appropriate privilege.

	      The address specified for
			     delta (or olddelta) is invalid.

	      If	     delta.tv_sec is greater than 31536000 (approx. 365 days) or less than -31536000.  The delta.tv_usec field is not used
			     in  calculation of these limits.  If the user wants to adjust time greater than these limits, an appropriate alterna-
			     tive interface should be used.

EXAMPLES
       The following code snippet will take the time forward 20 minutes.

       The following code fragment will repeatedly call a user-defined function until the adjustment requested in a previous call to (called  from
       either the same process or another process) is completed.

AUTHOR
       was developed by the University of California, Berkeley and AT&T.

SEE ALSO
       date(1), gettimeofday(2), stime(2), clock_settime(2), clocks(2), getitimer(2), setitimer(2), alarm(2), privileges(5).

																	adjtime(2)