How to Use the Command 'tzselect' (with examples)

The tzselect command is a utility that allows users to interactively determine the appropriate timezone for their system or specific use cases. The command is particularly beneficial for those who might not know the exact timezone they are in or require guidance through a user-friendly interface. Despite its usefulness, it’s important to note that tzselect does not actually set the timezone; it only helps users determine which timezone would be correct for their setup. Detailed information about this command can be found at tzselect .

Use case 1: Open the interactive menu for timezone selection and print the selected timezone to stdout

Code:

tzselect

Motivation:

This use case is ideal for users who need to identify their timezone interactively but do not have the precise details, such as timezone names or offsets, readily available. By running tzselect, users are guided through a series of prompts navigating through continents, countries, and regions to accurately determine the timezone where they are currently located or where they need to configure their system. This interactive choice makes the process accessible to users of all skill levels, eliminating the need for extensive geographical or timezone knowledge.

Explanation:

The tzselect command is executed without any additional arguments in this scenario. When invoked, it presents the user with interactive prompts and menus asking in sequential order about the continent, country, and sometimes a region within the country to refine the timezone selection process. After navigating through these prompts, the tool will output the selected timezone to stdout, which is the standard output stream on a terminal. This output can then be used by the user to set their timezone manually using other system utilities or to reference in applications requiring timezone information.

Example output:

Please identify a location so that time zone rules can be set correctly.
Please select a continent or ocean.
1) Africa
2) Americas
3) Antarctica
4) Asia
5) Atlantic Ocean
6) Australia
7) Europe
8) Indian Ocean
9) Pacific Ocean
#? 2
Please select a country whose clocks agree with yours.
1) Anguilla
2) Antigua & Barbuda
3) Argentina
4) Bahamas
5) Barbados
6) Belize
...
#? 3
Please select a region.
1) Buenos_Aires (BA, CF)
2) Catamarca (CT), Chubut (CH), La_Rioja (LR), San_Juan (SJ), San_Luis (SL)
3) Jujuy (JU), Formosa (FM), Salta (SA), Santiago_del_Estero (SE), Tucuman (TM)
...
#? 1
The following information has been given:

    Argentina
    Buenos_Aires (BA, CF)

Therefore TZ='America/Argentina/Buenos_Aires' will be used.
Local time is now:      Tue Oct 19 10:26:39 ART 2023.
Universal Time is now:  Tue Oct 19 13:26:39 UTC 2023.
Is the above information OK?
1) Yes
2) No
#? 1

You can make this change permanent for yourself by appending the line
    TZ='America/Argentina/Buenos_Aires'; export TZ
to the file .profile in your home directory; then log out and log in again.

Use case 2: Ask for nearest timezone to coordinates in ISO 6709 notation

Code:

tzselect -c coordinates

Motivation:

This use case is particularly useful for users who may have geographic coordinates available (in ISO 6709 notation) but are uncertain about what timezone those coordinates correspond to. For example, this scenario is common in scientific applications, logistics, or any systems involving GPS data where users might have raw location data but need corresponding timezone information for time calculation and planning. This precise input method ensures accurate conversion of geographic locations to timezones, minimizing human error and enhancing efficiency in operations requiring accurate time data.

Explanation:

The -c flag in the tzselect command stands for “coordinates.” This flag allows the user to input geographic coordinates in ISO 6709 notation, which is a standard representation of geographic locations using latitude and longitude. This notation typically includes latitude, longitude, and optionally altitude, formatted as a string like +DD.DDDD+DDD.DDDD. By passing these coordinates to tzselect, the utility will automatically calculate the closest timezone to the specified geographical point. The command’s output will indicate the most probable timezone for the entered coordinates.

Example output:

Assuming the entered coordinates are +37.7749-122.4194 (which corresponds to San Francisco, California, USA):

The coordinate +37.7749-122.4194 is approximately at
place: San Francisco, California, U.S.A
Time Zone: America/Los_Angeles
Is this information correct?
1) Yes
2) No
#? 1

The TZ database timezone is 'America/Los_Angeles'.

Conclusion:

The tzselect command is a useful utility for determining timezones interactively through a menu or by inputting specific geographical coordinates. It caters to users who prefer a guided walkthrough as well as those who have precise coordinate data but require timezone information. While tzselect does not set the timezone on its own, it is an informative tool that complements manual configuration and can be integrated with other system settings to enhance timezone management effectively.