1ADJTIME_CONFIG(5)                File formats                ADJTIME_CONFIG(5)
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NAME

6       adjtime_config - information about hardware clock setting and drift
7       factor
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SYNOPSIS

10       /etc/adjtime
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DESCRIPTION

13       The file /etc/adjtime contains descriptive information about the
14       hardware mode clock setting and clock drift factor. The file is read
15       and write by hwclock(8); and read by programs like rtcwake to get RTC
16       time mode.
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18       The file is usually located in /etc, but tools like hwclock(8) or
19       rtcwake(8) can use alternative location by command line options if
20       write access to /etc is unwanted. The default clock mode is "UTC" if
21       the file is missing.
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23       The Hardware Clock is usually not very accurate. However, much of its
24       inaccuracy is completely predictable - it gains or loses the same
25       amount of time every day. This is called systematic drift. The util
26       hwclock(8) keeps the file /etc/adjtime, that keeps some historical
27       information. For more details see "The Adjust Function" and "The
28       Adjtime File" sections from hwclock(8) man page.
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30       The format of the adjtime file is, in ASCII.
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32   First line
33       Three numbers, separated by blanks:
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35       drift factor
36           the systematic drift rate in seconds per day (floating point
37           decimal)
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39       last adjust time
40           the resulting number of seconds since 1969 UTC of most recent
41           adjustment or calibration (decimal integer)
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43       adjustment status
44           zero (for compatibility with clock(8)) as a floating point decimal
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46   Second line
47       last calibration time
48           The resulting number of seconds since 1969 UTC of most recent
49           calibration. Zero if there has been no calibration yet or it is
50           known that any previous calibration is moot (for example, because
51           the Hardware Clock has been found, since that calibration, not to
52           contain a valid time). This is a decimal integer.
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54   Third line
55       clock mode
56           Supported values are UTC or LOCAL. Tells whether the Hardware Clock
57           is set to Coordinated Universal Time or local time. You can always
58           override this value with options on the hwclock(8) command line.
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FILES

61       /etc/adjtime
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SEE ALSO

64       hwclock(8), rtcwake(8)
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REPORTING BUGS

67       For bug reports, use the issue tracker at
68       https://github.com/karelzak/util-linux/issues.
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AVAILABILITY

71       adjtime_config is part of the util-linux package which can be
72       downloaded from Linux Kernel Archive
73       <https://www.kernel.org/pub/linux/utils/util-linux/>.
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77util-linux 2.37.2                 2021-06-02                 ADJTIME_CONFIG(5)