adjtime_config(5)

ADJTIME_CONFIG(5)                File Formats                ADJTIME_CONFIG(5)

NAME
       adjtime - information about hardware clock setting and drift factor

SYNOPSIS
       /etc/adjtime

DESCRIPTION
       The  file /etc/adjtime contains descriptive information about the hard-
       ware mode clock setting and clock drift factor.  The file is  read  and
       write  by  hwclock;  and  read by programs like rtcwake to get RTC time
       mode.

       The file is usually located in  /etc,  but  tools  like  hwclock(8)  or
       rtcwake(8) allow to use alternative location by command line options if
       write access to /etc is unwanted.  The default clock mode is  "UTC"  if
       the file is missing.

       The  Hardware Clock is usually not very accurate.  However, much of its
       inaccuracy is completely predictable -  it  gains  or  loses  the  same
       amount  of  time every day.  This is called systematic drift.  The util
       hwclock keeps the file /etc/adjtime, that keeps some historical  infor-
       mation.   For  more details see "The Adjust Function" and  "The Adjtime
       File" sections from hwclock(8) man page.

       The format of the adjtime file is, in ASCII.

   First line
       Three numbers, separated by blanks:

       drift factor
              the systematic drift rate in seconds  per  day  (floating  point
              decimal)

       last adjust time
              the  resulting  number of seconds since  1969  UTC  of  most re-
              cent adjustment or calibration (decimal integer)

       adjustment status
              zero (for compatibility with clock(8)) as a floating point deci-
              mal

   Second line
       last calibration time
              The  resulting  number  of seconds since 1969 UTC of most recent
              calibration.  Zero if there has been no calibration yet or it is
              known  that  any  previous calibration is moot (for example, be-
              cause the Hardware Clock has been found, since that calibration,
              not to contain a valid time).  This is a decimal integer.

   Third line
       clock mode
              Supported  values are "UTC" or "LOCAL".  Tells whether the Hard-
              ware Clock is set to Coordinated Universal Time or  local  time.
              You  can  always override this value with options on the hwclock
              command line.

FILES
       /etc/adjtime

SEE ALSO
       hwclock(8), rtcwake(8)

AVAILABILITY
       This man page is part of the util-linux package and is  available  from
       https://www.kernel.org/pub/linux/utils/util-linux/.

util-linux                        August 2018                ADJTIME_CONFIG(5)