ntp_adjtime(2)

NAME

     ntp_adjtime - adjust local clock parameters

SYNOPSIS

     #include <sys/timex.h>

     int ntp_adjtime(struct timex *tptr);

DESCRIPTION

     The ntp_adjtime() function adjusts the  parameters  used  to
     discipline  the  local clock, according to the values in the
     struct timex pointed to by  tptr. Before returning, it fills
     in  the  structure  with  the most recent values kept in the
     kernel.

     The adjustment is effected in part by speeding up or slowing
     down  the  clock, as necessary, and in part by phase-locking
     onto a once-per second pulse (PPS) provided by a driver,  if
     available.

     struct timex {
         uint32_t modes;        /* clock mode bits (w) */
         int32_t  offset;       /* time offset (us) (rw) */
         int32_t  freq;         /* frequency offset (scaled ppm) (rw) */
         int32_t  maxerror;     /* maximum error (us) (rw) */
         int32_t  esterror;     /* estimated error (us) (rw) */
         int32_t  status;       /* clock status bits (rw) */
         int32_t  constant;     /* pll time constant (rw) */
         int32_t  precision;    /* clock precision (us) (r) */
         int32_t  tolerance;    /* clock frequency tolerance
                                   (scaled ppm) (r) */
         int32_t  ppsfreq;      /* pps frequency (scaled ppm) (r) */
         int32_t  jitter;       /* pps jitter (us) (r) */
         int32_t  shift;        /* interval duration (s) (shift) (r) */
         int32_t  stabil;       /* pps stability (scaled ppm) (r) */
         int32_t  jitcnt;       /* jitter limit exceeded (r) */
         int32_t  calcnt;       /* calibration intervals (r) */
         int32_t  errcnt;       /* calibration errors (r) */
         int32_t  stbcnt;       /* stability limit exceeded (r) */
     };

RETURN VALUES

     Upon  successful  completion,  ntp_adjtime()   returns   the
     current  clock  state  (see  <sys/timex.h>).   Otherwise, it
     returns -1 and sets errno to indicate the error.

ERRORS

     The ntp_adjtime() function will fail if:

      EFAULT
           The  tptr argument is an invalid pointer.

     EINVAL
           The constant member of the  structure  pointed  to  by
           tptr is less than 0 or greater than 30.

     EPERM The user is not super-user.

SEE ALSO

     xntpd(1M), ntp_gettime(2)