Detailed explanation of hwclock command

hwclock Introduction

The hwclock command is used to set or read the system hardware clock. This clock is usually a battery-powered clock on the computer's motherboard.

Set the clock

To set the hardware clock, use the following syntax:

<code>hwclock --set --date="MMDDhhmm[[[[cc]yy]]]"</code>

Where:

• --set: Specifies to set the clock.
• --date: followed by the date and time to be set.
• MM: Month (for example, 01 means January)
• DD: Day (for example, 01 means 1st)
• hh: Hours (for example, 01 means 1 o'clock)
• mm: Minutes (for example, 01 means 1 minute)
• cc: Century (for example, 20 for the 21st century)
• yy: Year (for example, 20 for 2020)

For example, to To set the hardware clock to January 1, 2023, 12:00 AM, use the following command:

<code>hwclock --set --date="010100002023"</code>

Read Clock

To read the hardware clock, Just enter the following command:

<code>hwclock</code>

It will print the current clock value in your console.

Options

The hwclock command also provides the following options:

• --localtime: Display time as local time.
• --utc: Displays the time as Coordinated Universal Time (UTC).
• --show: Only displays the current time and does not set anything.
• --backup: Back up the current time to a file.
• --restore: The time to restore the previous backup from the file.
• --systohc: Synchronize the system clock to the hardware clock.
• --hctoys: Synchronize the hardware clock to the system clock.

Example

To synchronize the hardware clock with the system clock, use the following command:

<code>hwclock --systohc</code>

To copy from file timebackup To restore the time of a previous backup, use the following command:

<code>hwclock --restore --file=/path/to/timebackup</code>

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