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ntp_gettime(2)
NAME
  ntp_gettime - Get 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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