NAME
adjtime - correct the time to allow synchronization of the system
clock

SYNOPSIS
#include <sys/time.h>

adjtime(delta, olddelta)
struct timeval *delta;
struct timeval *olddelta;

DESCRIPTION
Adjtime makes small adjustments to the system time, as returned by
gettimeofday(2), advancing or retarding it by the time specified by
the timeval delta. If delta is negative, the clock is slowed down
by incrementing it more slowly than normal until the correction is
complete. If delta is positive, a larger increment than normal is
used. The skew used to perform the correction is generally a
fraction of one percent. Thus, the time is always a monotonically
increasing function. A time correction from an earlier call to
adjtime may not be finished when adjtime is called again. If
olddelta is non-zero, then the structure pointed to will contain,
upon return, the number of microseconds still to be corrected from
the earlier call.

This call may be used by time servers that synchronize the clocks
of computers in a local area network. Such time servers would slow
down the clocks of some machines and speed up the clocks of others
to bring them to the average network time.

The call adjtime(2) is restricted to the super-user.

RETURN VALUE
A return value of 0 indicates that the call succeeded. A return
value of -1 indicates that an error occurred, and in this case an
error code is stored in the global variable errno.

ERRORS
The following error codes may be set in errno:

[EFAULT] An argument points outside the process’s allocated
address space.

[EPERM] The process’s effective user ID is not that of the
super-user.

SEE ALSO
date(1), gettimeofday(2), timed(8)*, timedc(8)*,
TSP: The Time Synchronization Protocol for UNIX 4.3BSD, R. Gusella
and S. Zatti

__________
* Not currently supported under MachTen