The
adjtime ();
system call
makes small adjustments to the system time, as returned by
gettimeofday(2),
advancing or retarding it
by the time specified by the timeval
Fa delta .
If
Fa delta
is negative, the clock is
slowed down by incrementing it more slowly than normal until
the correction is complete.
If
Fa 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
Fa olddelta
is not a null pointer,
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
adjtime ();
system call
is restricted to the super-user.
RETURN VALUES
Rv -std adjtime
ERRORS
The
adjtime ();
system call will fail if:
Bq Er EFAULT
An argument points outside the process's allocated address space.
Bq Er EPERM
The process's effective user ID is not that of the super-user.
