Manual page for ADJTIME(2)
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
Created by unroff & hp-tools.
© somebody (See intro for details). All Rights Reserved.
Last modified 11/5/97
