NAME

adjfreq — correct the rate of the system clock

SYNOPSIS

#include <>
#include <>

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

Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the error.

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.