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diff --git a/sys-utils/adjtime_config.5 b/sys-utils/adjtime_config.5 new file mode 100644 index 0000000..6f03ca7 --- /dev/null +++ b/sys-utils/adjtime_config.5 @@ -0,0 +1,64 @@ +.TH ADJTIME_CONFIG 5 "August 2018" "util-linux" "File Formats" +.SH NAME +adjtime \- information about hardware clock setting and drift factor +.SH SYNOPSIS +.I /etc/adjtime +.SH DESCRIPTION +The file +.B /etc/adjtime +contains descriptive information about the hardware 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. +.PP +The file is usually located in /etc, but tools like +.BR hwclock (8) +or +.BR 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. +.PP +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 information. +For more details see "\fBThe Adjust Function\fR" and "\fBThe Adjtime File\fR" sections from +.BR hwckock (8) +man page. +.PP + +The format of the adjtime file is, in ASCII. +.sp +.SS First line +Three numbers, separated by blanks: +.TP +.B "drift factor" +the systematic drift rate in seconds per day (floating point decimal) +.TP +.B last adjust time +the resulting number of seconds since 1969 UTC of most recent adjustment or calibration (decimal integer) +.TP +.B "adjustment status" +zero (for compatibility with clock(8)) as a decimal integer. + +.SS Second line +.TP +.B "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. + +.SS Third line +.TP +.B "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 command line. + +.SH FILES +.IR /etc/adjtime +.SH "SEE ALSO" +.BR hwclock (8), +.BR rtcwake (8) +.SH AVAILABILITY +This man page is part of the util-linux package and is available from +https://www.kernel.org/pub/linux/utils/util-linux/. |