1ADJTIME_CONFIG(5)                File Formats                ADJTIME_CONFIG(5)
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NAME

6       adjtime - information about hardware clock setting and drift factor
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SYNOPSIS

9       /etc/adjtime
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DESCRIPTION

12       The  file /etc/adjtime contains descriptive information about the hard‐
13       ware mode clock setting and clock drift factor.  The file is  read  and
14       write  by  hwclock;  and  read by programs like rtcwake to get RTC time
15       mode.
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17       The file is usually located in  /etc,  but  tools  like  hwclock(8)  or
18       rtcwake(8) allow to use alternative location by command line options if
19       write access to /etc is unwanted.  The default clock mode is  "UTC"  if
20       the file is missing.
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22       The  Hardware Clock is usually not very accurate.  However, much of its
23       inaccuracy is completely predictable -  it  gains  or  loses  the  same
24       amount  of  time every day.  This is called systematic drift.  The util
25       hwclock keeps the file /etc/adjtime, that keeps some historical  infor‐
26       mation.   For  more details see "The Adjust Function" and  "The Adjtime
27       File" sections from hwckock(8) man page.
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29       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
41              recent adjustment or calibration (decimal integer)
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43       adjustment status
44              zero (for compatibility with clock(8)) as a decimal integer.
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47   Second line
48       last calibration time
49              The resulting number of seconds since 1969 UTC  of  most  recent
50              calibration.  Zero if there has been no calibration yet or it is
51              known that  any  previous  calibration  is  moot  (for  example,
52              because  the  Hardware Clock has been found, since that calibra‐
53              tion, not to contain a valid time).  This is a decimal integer.
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56   Third line
57       clock mode
58              Supported values are "UTC" or "LOCAL".  Tells whether the  Hard‐
59              ware  Clock  is set to Coordinated Universal Time or local time.
60              You can always override this value with options on  the  hwclock
61              command line.
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FILES

65       /etc/adjtime
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SEE ALSO

68       hwclock(8), rtcwake(8)
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AVAILABILITY

71       This  man  page is part of the util-linux package and is available from
72       https://www.kernel.org/pub/linux/utils/util-linux/.
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76util-linux                        August 2018                ADJTIME_CONFIG(5)