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ntp_gettime(2)
NAME
  ntp_gettime - Gets the date, time, and kernel time error values.

SYNOPSIS
  #include <sys/timex.h>

  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
  following 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.

Index for Section 2

Alphabetical listing for N

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