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ntp_gettime(2)						       ntp_gettime(2)



NAME

  ntp_gettime -	Gets the date, time, and kernel	time error values.

SYNOPSIS

  #include <&lt;sys/timex.h>&gt;

  int ntp_gettime (struct ntptimeval *tp);

PARAMETERS

  tp  Points to	the ntptimeval structure in which information is returned.
      The ntptimeval structure is described in the sys/timex.h header file.

DESCRIPTION

  The ntp_gettime() system call	returns	three read-only	values in the
  ntptimeval structure.	 The ntptimeval	structure members are as follows:

  struct timeval time
	    The	current	system time expressed as a Unix	timeval	structure.
	    The	timeval	structure consists of two 32-bit words:	the first is
	    the	number of seconds past 1 January 1970 assuming no intervening
	    leap-second	insertions or deletions; and the second	is the number
	    of microseconds within the second.

  long maxerror
	    The	value of the time_maxerror kernel variable, which represents
	    the	maximum	error of the indicated time relative to	the primary
	    synchronization source, in microseconds.  For NTP, the value is
	    initialized	to the synchronization distance, which is equal	to
	    the	root dispersion	plus one-half the root delay.  It is
	    increased by a small amount	(time_tolerance) each second to
	    reflect the	maximum	clock frequency	error.	This variable is
	    modified by	the kernel, but	is otherwise not used by the kernel.

  long esterror
	    The	value of the time_esterror kernel variable, which represents
	    the	expected error of the indicated	time relative to the primary
	    synchronization source, in microseconds.  For NTP, the value is
	    determined as the root dispersion, which represents	the best
	    estimate of	the actual error of the	system clock based on its
	    past behavior, together with observations of multiple clocks
	    within the peer group.  This variable is not used by the kernel.

RETURN VALUES

  Upon successful completion, a	value of 0 (zero) is returned.	Otherwise, a
  value	of -1 is returned and errno is set to indicate the error.



ERRORS

  If the ntp_gettime() function	fails, errno may be set	to one of the follow-
  ing values:

  [EFAULT]  The	tp parameter points to a location outside of the allocated
	    address space of the process.

  [ENOSYS]  The	kernel was configured without the NTP_TIME option.