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 hwclock(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 floating point deci‐
45              mal
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48   Second line
49       last calibration time
50              The  resulting  number  of seconds since 1969 UTC of most recent
51              calibration.  Zero if there has been no calibration yet or it is
52              known  that  any  previous  calibration  is  moot  (for example,
53              because the Hardware Clock has been found, since  that  calibra‐
54              tion, not to contain a valid time).  This is a decimal integer.
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57   Third line
58       clock mode
59              Supported  values are "UTC" or "LOCAL".  Tells whether the Hard‐
60              ware Clock is set to Coordinated Universal Time or  local  time.
61              You  can  always override this value with options on the hwclock
62              command line.
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FILES

66       /etc/adjtime
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SEE ALSO

69       hwclock(8), rtcwake(8)
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AVAILABILITY

72       This man page is part of the util-linux package and is  available  from
73       https://www.kernel.org/pub/linux/utils/util-linux/.
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77util-linux                        August 2018                ADJTIME_CONFIG(5)