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28 .\" @(#)adjtime.2 8.1 (Berkeley) 6/4/93
29 .\" $FreeBSD: src/lib/libc/sys/adjtime.2,v 1.6.2.4 2001/12/14 18:34:00 ru Exp $
36 .Nd "correct the time to allow synchronization of the system clock"
42 .Fn adjtime "const struct timeval *delta" "struct timeval *olddelta"
45 makes small adjustments to the system time, as returned by
47 advancing or retarding it
48 by the time specified by the timeval
52 is negative, the clock is
53 slowed down by incrementing it more slowly than normal until
54 the correction is complete.
57 is positive, a larger increment than normal
59 The skew used to perform the correction is generally a fraction of one percent.
60 Thus, the time is always
61 a monotonically increasing function.
62 A time correction from an earlier call to
64 may not be finished when
70 the structure pointed to will contain, upon return, the
71 number of microseconds still to be corrected
72 from the earlier call.
74 This call may be used by time servers that synchronize the clocks
75 of computers in a local area network.
76 Such time servers would slow down the clocks of some machines
77 and speed up the clocks of others to bring them to the average network time.
81 is restricted to the super-user.
89 An argument points outside the process's allocated address space.
91 The process's effective user ID is not that of the super-user.
99 function call appeared in