ntp_gettime(3) - BetterMan

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time	The current time, expressed as a timeval structure:
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()	NTP Kernel Application Program Interface.
ntp_gettimex()	GNU.
ntp_gettime()	glibc 2.1.
ntp_gettimex()	glibc 2.12.

NAME

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

LIBRARY

Standard C library (libc, -lc)

SYNOPSIS

bash

#include <sys/timex.h>

bash

int ntp_gettime(struct ntptimeval *\nntv\n);\n
\nint ntp_gettimex(struct ntptimeval *\nntv\n);

DESCRIPTION

Both of these APIs return information to the caller via the ntv argument, a structure of the following type:

bash

struct ntptimeval {
\n
    struct timeval time;    /* Current time */
\n
    long maxerror;          /* Maximum error */
\n
    long esterror;          /* Estimated error */
\n
    long tai;               /* TAI offset */
\n
    /* Further padding bytes allowing for future expansion */
};

The fields of this structure are as follows:

time: The current time, expressed as a timeval structure:

: bash
struct timeval { \n time_t tv_sec; /* Seconds since the Epoch */ \n 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, maxerror, 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 adjtimex(2). Given a correct pointer argument, these functions always succeed.

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

STANDARDS

ntp_gettime(): NTP Kernel Application Program Interface.
ntp_gettimex(): GNU.

HISTORY

ntp_gettime(): glibc 2.1.
ntp_gettimex(): glibc 2.12.