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Annotation of 43BSDTahoe/man/man2/adjtime.2, revision 1.1.1.1

1.1       root        1: .\" Copyright (c) 1980 Regents of the University of California.
                      2: .\" All rights reserved.
                      3: .\"
                      4: .\" Redistribution and use in source and binary forms are permitted
                      5: .\" provided that the above copyright notice and this paragraph are
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                      8: .\" distribution and use acknowledge that the software was developed
                      9: .\" by the University of California, Berkeley.  The name of the
                     10: .\" University may not be used to endorse or promote products derived
                     11: .\" from this software without specific prior written permission.
                     12: .\" THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
                     13: .\" IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
                     14: .\" WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
                     15: .\"
                     16: .\"    @(#)adjtime.2   1.5 (Berkeley) 7/9/88
                     17: .\"
                     18: .TH ADJTIME 2 "July 9, 1988"
                     19: .UC 6
                     20: .SH NAME
                     21: adjtime \- correct the time to allow synchronization of the system clock
                     22: .SH SYNOPSIS
                     23: .nf
                     24: .ft B
                     25: #include <sys/time.h>
                     26: .PP
                     27: .ft B
                     28: adjtime(delta, olddelta)
                     29: struct timeval *delta; 
                     30: struct timeval *olddelta;
                     31: .fi
                     32: .SH DESCRIPTION
                     33: .I Adjtime
                     34: makes small adjustments to the system time, as returned by
                     35: .IR gettimeofday (2),
                     36: advancing or retarding it
                     37: by the time specified by the timeval
                     38: \fIdelta\fP.
                     39: If \fIdelta\fP is negative, the clock is
                     40: slowed down by incrementing it more slowly than normal until
                     41: the correction is complete.
                     42: If \fIdelta\fP is positive, a larger increment than normal
                     43: is used.
                     44: The skew used to perform the correction is generally a fraction of one percent.
                     45: Thus, the time is always
                     46: a monotonically increasing function.
                     47: A time correction from an earlier call to \fIadjtime\fP
                     48: may not be finished when \fIadjtime\fP is called again.
                     49: If \fIolddelta\fP is non-zero,
                     50: then the structure pointed to will contain, upon return, the
                     51: number of microseconds still to be corrected
                     52: from the earlier call.
                     53: .PP
                     54: This call may be used by time servers that synchronize the clocks
                     55: of computers in a local area network.
                     56: Such time servers would slow down the clocks of some machines
                     57: and speed up the clocks of others to bring them to the average network time.
                     58: .PP
                     59: The call 
                     60: .IR adjtime (2)
                     61: is restricted to the super-user.
                     62: .SH "RETURN VALUE
                     63: A return value of 0 indicates that the call succeeded.
                     64: A return value of \-1 indicates that an error occurred, and in this
                     65: case an error code is stored in the global variable \fIerrno\fP.
                     66: .SH "ERRORS
                     67: The following error codes may be set in \fIerrno\fP:
                     68: .TP 15
                     69: [EFAULT]
                     70: An argument points outside the process's allocated address space.
                     71: .TP 15
                     72: [EPERM]
                     73: The process's effective user ID is not that of the super-user.
                     74: .SH "SEE ALSO"
                     75: date(1), gettimeofday(2), timed(8), timedc(8),
                     76: .br
                     77: \fITSP: The Time Synchronization Protocol for UNIX 4.3BSD\fP, 
                     78: R. Gusella and S. Zatti

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