[thirdparty/util-linux.git] / sys-utils / adjtime_config.5.adoc

//po4a: entry man manual
= adjtime_config(5)
:doctype: manpage
:man manual: File formats
:man source: util-linux {release-version}
:page-layout: base
:configfile: adjtime_config

== 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)

include::man-common/bugreports.adoc[]

include::man-common/footer-config.adoc[]

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Commit	Line	Data
295b3979	1	//po4a: entry man manual
6d5b6948 MB	2	= adjtime_config(5)
	3	:doctype: manpage
	4	:man manual: File formats
	5	:man source: util-linux {release-version}
	6	:page-layout: base
	7	:configfile: adjtime_config
	8
	9	== NAME
	10
	11	adjtime_config - information about hardware clock setting and drift factor
	12
	13	== SYNOPSIS
	14
	15	_/etc/adjtime_
	16
	17	== DESCRIPTION
	18
	19	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.
	20
	21	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.
	22
	23	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.
	24
344b0cd4	25	The _adjtime_ file is formatted in ASCII.
6d5b6948 MB	26
	27	=== First line
	28
	29	Three numbers, separated by blanks:
	30
	31	drift factor::
68860732	32	the systematic drift rate in seconds per day (floating point decimal)
6d5b6948 MB	33
6d5b6948 MB	34	last adjust time::
68860732	35	the resulting number of seconds since 1969 UTC of most recent adjustment or calibration (decimal integer)
6d5b6948 MB	36
6d5b6948 MB	37	adjustment status::
68860732	38	zero (for compatibility with clock(8)) as a floating point decimal
6d5b6948 MB	39
	40	=== Second line
	41
	42	last calibration time::
68860732	43	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.
6d5b6948 MB	44
	45	=== Third line
	46
	47	clock mode::
68860732	48	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.
6d5b6948 MB	49
	50	== FILES
	51
	52	_/etc/adjtime_
	53
	54	== SEE ALSO
	55
	56	hwclock(8),
	57	rtcwake(8)
	58
625e9c61	59	include::man-common/bugreports.adoc[]
6d5b6948	60
625e9c61	61	include::man-common/footer-config.adoc[]
6d5b6948 MB	62
6d5b6948 MB	63	ifdef::translation[]
625e9c61	64	include::man-common/translation.adoc[]
6d5b6948	65	endif::[]