ADJFREQ(2)

NAME
adjfreq - correct the rate of the system clock

SYNOPSIS
#include <sys/types.h>
#include <sys/time.h>
int
adjfreq(const int64_t *freq, int64_t *oldfreq);

DESCRIPTION
adjfreq() adjusts the rate in which time progresses if freq is non-null. The unit of the rate of adjustment is nanoseconds per second, shifted left 32 bits to allow for fractional values.

If oldfreq is non-null, the current value is returned.

Only the superuser may adjust the frequency.

RETURN VALUES

ERRORS
adjfreq() will fail if:

[EFAULT]
    Either of the arguments point outside the process's allocated address space.

[EPERM]
    The freq argument is non-null and the process's effective user ID is not that of the superuser.

[EINVAL]
    freq is less than -500000 ppm or greater than 500000 ppm.

SEE ALSO
date(1), adjtime(2), gettimeofday(2), ntpd(8)

HISTORY
The adjfreq() function call first appeared in OpenBSD 4.0.