ADJTIME_CONFIG(5) File formats ADJTIME_CONFIG(5)
NAME
adjtime_config - information about hardware clock setting and drift
factor
SYNOPSIS
/etc/adjtime
DESCRIPTION
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.
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 recent
adjustment or calibration (decimal integer)
adjustment status
zero (for compatibility with clock(8)) as a floating point decimal
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, because
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 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.
FILES
/etc/adjtime
SEE ALSO
hwclock(8), rtcwake(8)
REPORTING BUGS
For bug reports, use the issue tracker at
https://github.com/util-linux/util-linux/issues.
AVAILABILITY
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/>.
util-linux 2.38.1 2022-05-11 ADJTIME_CONFIG(5)
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