.\" Copyright (c) 1980 Regents of the University of California.
.\" All rights reserved. The Berkeley software License Agreement
.\" specifies the terms and conditions for redistribution.
.\" @(#)adjtime.2 1.1 (Berkeley) %G%
adjtime \- correct the time to allow synchronization of the system clock
struct timeval *olddelta;
changes the system time, as returned by
moving it backward or forward
by the number of microseconds corresponding to the timeval
The time is maintained by incrementing it with a machine-dependent tick
If \fIdelta\fP is negative, the clock is
slowed down by incrementing it in smaller ticks until
If \fIdelta\fP is positive, a larger tick
a monotonically increasing function.
A time correction from an earlier call to \fIadjtime\fP
may not be finished when \fIadjtime\fP is called again.
If \fIolddelta\fP is non-zero,
then the structure pointed to will contain, upon return, the
number of microseconds still to be corrected
This call can be used in 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.
is restricted to the super-user.
On a VAX the time is incremented
When \fIadjtime\fP is called with an argument other than zero,
ticks of 9ms or 11ms are used until the time is corrected.
A \fIdelta\fP of less than 1ms would have no effect.
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 \fIerrno\fP.
The following error codes may be set in \fIerrno\fP:
An argument points outside the process's allocated address space.
The process's effective user ID is not that of the super-user.
date(1), gettimeofday(2), timed(8), timedc(8),
\fITSP: The Time Synchronization Protocol for UNIX 4.3BSD\fP,
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