Linux command hwclock command and Man command

Source: Internet
Author: User
Tags time zones local time time and date

Hwclock:function Description

Displays and sets the hardware clock.

Grammar

Hwclock[--adjust][--debug][--directisa][--hctosys][--show][--systohc][--test]

[--utc][--version][--set--date=< date and time;]

Additional Information

The hardware clock is the clock device on the motherboard, which is usually the clock that can be set on the BIOS screen. the system clock refers to the clock in the kernel. When Linux starts, the system clock reads the settings of the hardware clock, and then the system clock runs independently. All Linux-related instructions and functions are programmed to read the system clock.

Linux when the hardware clock is set, two time zones are available, one is the local time zone, and the hardware time is the same as the system time, and the other is the UTC time zone, at which time the hardware time is in UTC, and the system is initialized to the local time before it is set to the system clock.

Parameters

--adjust Hwclock every time the hardware clock is changed, it is recorded in the/etc/ Adjtime file. Using the--adjust parameter allows the hwclock to estimate hardware clock deviations based on previous records and to calibrate the hardware clock.

--debug displays detailed information about the Hwclock execution.

--directisa Hwclock presets To access hardware clocks from/DEV/RTC devices. If not accessible, this parameter can be used to access the hardware clock directly with the I/O instruction.

--hctosys will be system Clock adjust to match the hardware clock. The hwclock converts the hardware time to the local time zone in accordance with the hardware clock's timezone,

--set--date=< Date and time > Set hardware clock.

--show Displays the time and date of the hardware clock.

--SYSTOHC adjust the hardware clock to match the system clock. When you set the hardware clock, Hwclock automatically converts the system time to the time zone of the hardware clock.

--test only Test Program without actually changing the hardware clock.

--UTC treat hardware time as UTC time. To use Greenwich mean, add this parameter, and Hwclock will perform the conversion work.

--localtime the hardware clock is treated as a local time, and Hwclock does not perform time conversion work at this point.

--version Displays version information.

Mans :

NAME : Command name and function brief description

Synopsis : Usage notes, including available options

DESCRIPTION : A detailed description of the command function, which may include the meaning of each option

OPTIONS : Explains the meaning of each option

FILES : The configuration file associated with this command

BUGS :

EXAMPLES : Using the example

See ALSO : Another reference

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Linux command hwclock command and Man command

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