NTP_GETTIME(3)		   Linux Programmer's Manual		NTP_GETTIME(3)



NAME
       ntp_gettime, ntp_gettimex  - get time parameters (NTP daemon interface)

SYNOPSIS
       #include <sys/timex.h>

       int ntp_gettime(struct ntptimeval *ntv);

       int ntp_gettimex(struct ntptimeval *ntv);

DESCRIPTION
       Both  of	 these APIs return information to the caller via the ntv argu-
       ment, a structure of the following type:

	   struct ntptimeval {
	       struct timeval time;	   /* Current time */
	       long int maxerror;	   /* Maximum error */
	       long int esterror;	   /* Estimated error */
	       long int tai;		   /* TAI offset */

	       /* Further padding bytes allowing for future expansion */
	   };

       The fields of this structure are as follows:

       time   The current time, expressed as a timeval structure:

		  struct timeval {
		      time_t	  tv_sec;   /* Seconds since the Epoch */
		      suseconds_t tv_usec;  /* Microseconds */
		  };


       maxerror
	      Maximum error, in microseconds.  This value can  be  initialized
	      by ntp_adjtime(3), and is increased periodically (on Linux: each
	      second), but is clamped to an upper limit (the  kernel  constant
	      NTP_PHASE_MAX, with a value of 16,000).

       esterror
	      Estimated	 error,	 in  microseconds.   This value can be set via
	      ntp_adjtime(3) to contain an estimate of the difference  between
	      the  system  clock  and  the  true time.	This value is not used
	      inside the kernel.

       tai    TAI (Atomic International Time) offset.

       ntp_gettime() returns an ntptimeval structure in which the time, maxer-
       ror, and esterror fields are filled in.

       ntp_gettimex()  performs	 the  same  task  as  ntp_gettime(),  but also
       returns information in the tai field.

RETURN VALUE
       The return values for ntp_gettime() and ntp_gettimex() are as for  adj-
       timex(2).   Given  a  correct  pointer argument, these functions always
       succeed.

VERSIONS
       The ntp_gettime() function is available since glibc 2.1.	 The  ntp_get-
       timex() function is available since glibc 2.12.

ATTRIBUTES
       For   an	  explanation	of   the  terms	 used  in  this	 section,  see
       attributes(7).

       +-------------------------------+---------------+---------+
       |Interface		       | Attribute     | Value	 |
       +-------------------------------+---------------+---------+
       |ntp_gettime(), ntp_gettimex()  | Thread safety | MT-Safe |
       +-------------------------------+---------------+---------+
CONFORMING TO
       ntp_gettime() is described in the NTP Kernel Application Program Inter-
       face.  ntp_gettimex() is a GNU extension.

SEE ALSO
       adjtimex(2) ntp_adjtime(3), time(7)

       NTP "Kernel Application Program Interface"
       <http://www.slac.stanford.edu/comp/unix/package/rtems/src/ssrlApps/
       ntpNanoclock/api.htm>

COLOPHON
       This page is part of release 4.10 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.



Linux				  2016-10-08			NTP_GETTIME(3)