| 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
#include <sys/timex.h>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:
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.
SEE ALSO
adjtimex(2), ntp_adjtime(3), time(7)
NTP "Kernel Application Program Interface" (opens in new tab)