How to Use the Command 'timedatectl' (with Examples)

The timedatectl command is a versatile tool in Linux used to control and query the system clock and its settings. It provides an interface for adjusting both system time and date, configuring settings related to time zones, and managing Network Time Protocol (NTP) synchronization. This command is particularly useful for system administrators and users who need precise control over time settings for applications, scheduling, or correcting discrepancies in system time. Below, we’ll explore various use cases for timedatectl.

Check the Current System Clock Time

Code:

timedatectl

Motivation: Checking the current system time and settings is a routine but crucial task. Whether for troubleshooting, logging, or confirming time-related configurations, having the correct system time is essential for many operations in both personal and professional computing environments. The timedatectl command provides a straightforward way to view this information comprehensively.

Explanation: When executed without additional arguments, timedatectl queries the current status of the system clock. This includes details such as the local time, universal time, time zone, and NTP synchronization status.

Example Output:

Local time: Mon 2023-10-16 14:08:52 EDT
Universal time: Mon 2023-10-16 18:08:52 UTC
RTC time: Mon 2023-10-16 18:08:51
Time zone: America/New_York (EDT, -0400)
System clock synchronized: yes
NTP service: active

Set the Local Time of the System Clock Directly

Code:

timedatectl set-time "2023-10-16 14:10:00"

Motivation: Manually setting the system time can be vital in scenarios where the system time needs to be corrected quickly, such as after a time drift caused by hardware issues or when setting up a system in a non-networked environment where NTP is inaccessible.

Explanation: Here, the set-time argument is followed by the desired date and time in the format “yyyy-MM-dd hh:mm:ss”. This directly updates the system clock to the specified time.

Example Output: The command itself does not provide output, but you can verify the change by running timedatectl again.

Example Verification Output:

Local time: Mon 2023-10-16 14:10:00 EDT

List Available Timezones

Code:

timedatectl list-timezones

Motivation: Knowing which time zones are available on a system is essential for setting correct time zone settings, particularly in a multinational environment or when traveling across different time zones. This allows users to ensure their systems reflect the accurate local time.

Explanation: The list-timezones argument tells timedatectl to output a list of all time zones supported by the system. This list can be extensive, covering every known time zone worldwide.

Example Output: A snippet of the possible output might look like:

Africa/Abidjan
Africa/Accra
Africa/Addis_Ababa
Africa/Algiers
...
America/New_York
...

Set the System Timezone

Code:

timedatectl set-timezone America/New_York

Motivation: Setting the correct time zone is crucial for maintaining proper system time, accounting for daylight saving changes, and ensuring logs and scheduled tasks align with regional time settings. This is especially important for users working in or with clients in different geographical locations.

Explanation: The set-timezone argument lets you specify a new time zone for the system. It requires the correct time zone identifier, which can be determined from the list provided by list-timezones.

Example Output: Like the set-time command, this command does not produce output but changes the system’s time zone. You can confirm the change by re-running timedatectl.

Enable Network Time Protocol (NTP) Synchronization

Code:

timedatectl set-ntp on

Motivation: Enabling NTP synchronization ensures that the system clock is automatically adjusted to the correct time using a network time server. This is vital for maintaining time accuracy, especially on systems involved in time-sensitive operations or those that need to remain synchronized with other networked systems.

Explanation: The set-ntp argument enables or disables NTP synchronization. Using on turns NTP synchronization on, ensuring the system time is regularly updated automatically.

Example Output: No immediate output is shown, but you can verify that NTP is active with the timedatectl command.

Example Verification Output:

NTP service: active

Change the Hardware Clock Time Standard to Localtime

Code:

timedatectl set-local-rtc 1

Motivation: In situations where the hardware clock must be set to local time rather than universal time (UTC), especially if using dual-boot with an operating system like Windows (which expects the hardware clock to be set to local time), this command becomes quite useful.

Explanation: The set-local-rtc argument, followed by 1, sets the hardware clock to local time, while a 0 sets it to UTC. This parameter is particularly relevant for compatibility with systems expecting a specific time standard.

Example Output: The command itself does not produce output. Use timedatectl to check if the hardware clock is using local time or UTC.

Example Verification Output:

RTC in local TZ: yes

Conclusion

The timedatectl command is a powerful tool that provides comprehensive control and management of time and date settings on Linux systems. Whether checking system time, changing time zones, or managing NTP synchronization, timedatectl offers the capabilities necessary for precise time management, essential for both individual users and businesses reliant on accurate scheduling and logging.