adjtime_config - information about hardware clock setting and drift factor
/etc/adjtime
The file /etc/adjtime
contains descriptive information about
the hardware mode clock setting and clock drift factor. The file is read
and write by hwclock(8); 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) can 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(8) keeps the file /etc/adjtime
, that
keeps some historical information. For more details see "The
Adjust Function" and "The Adjtime File"
sections from hwclock(8) man page.
The adjtime
file is formatted in ASCII.
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 recent adjustment or calibration (decimal integer)
adjustment status
zero (for compatibility with clock(8)) as a floating point decimal
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, because the Hardware Clock has been found, since that calibration, not to contain a valid time). This is a decimal integer.
clock mode
Supported values are UTC or LOCAL. Tells whether the Hardware Clock is set to Coordinated Universal Time or local time. You can always override this value with options on the hwclock(8) command line.
/etc/adjtime
For bug reports, use the issue tracker at <https://github.com/util-linux/util-linux/issues>.
adjtime_config is part of the util-linux package
which can be downloaded from Linux Kernel Archive
<https://www.kernel.org/pub/linux/utils/util-linux/>.