How to Display and Set Date and Time in Linux | date Command
Unlock the full potential of the date command in Linux—a versatile tool that does more than just show the current date and time. With this command, you can set your system’s clock, synchronize time across networks, and even calculate past or future dates for tasks like scheduling or logging. In this comprehensive tutorial, you’ll learn how to:
- Display the current date and time
- Set the system date and time
- Use date format specifiers to customize outputs:
In this tutorial, we will walk you through the process of how to display date and time in Linux, change system settings, and work with Linux date format specifiers to format output.
What is the date Command in Linux
The date command in Linux allows the user to display the current date and time in a variety of formats and set the system date and time. Being a part of the core utilities in Linux and Unix-like operating systems, it makes it an essential command for system configuration and scripting.
However, by default, the date displays the current time in the system's configured timezone. It supports formatting using the special date format specifiers to display the time exactly the way you need it.
Key uses of the date Command
- Displaying the Current Date and Time
- Setting the System Date and Time
- Customizing the Output Format
- Performing Date Calculations
- Displaying Time in Different Time Zones
Syntax of date Command in Linux
The basic syntax for the date command is:
date [OPTION]... [+FORMAT]
date [-u|--utc|--universal] [MMDDhhmm[[CC]YY][.ss]]
where,
- OPTION: Refers to different flags & arguments that modify the behaviour of the command.
- FORMAT: Refers to "how you want to display" the date, using format specifiers. (such as %Y, %m, %d).
How to Display and Set Date and Time in Linux: 9 Different Formats
In this guide, we're going to explore different methods of displaying the system's date and time in Linux. Let's get this started:
1. Display Current Date and Time in Linux
The date command displays the current date and time, including the abbreviated day name, abbreviated month name, day of the month, the time separated by colons, the time zone name, and the year.
Command:
date
Output:
Note: Here unix system is configured in Pacific daylight time and displaying the day, date, time, timezone, and year.
2. Display Time in GMT/UTC
The -u option with the date command allows you to display the current time in GMT (Greenwich Mean Time) or UTC (Coordinated Universal Time) instead of your system's local time zone.
Command:
date -u
Output:
3. Display the Given Date String in the Format of Date
--date or -d Option: Displays the given date string in the format of date. But this will not affect the system's actual date and time value.Rather it uses the date and time given in the form of string.
Syntax:
date --date=" string "
Command:
$date --date="2/02/2010"
$date --date="Feb 2 2010"
Output:
Tue Feb 2 00:00:00 PST 2010
Tue Feb 2 00:00:00 PST 2010
4. Display Past Dates
You can also display past dates using tje --date option. Below, we're displaying the date and time of 2 years ago:
Example 1:
date --date="2 year ago"
Example 2:
Date and time of 5 seconds ago
date --date="5 sec ago"
Example 3:
Date and time of previous day
date --date="yesterday"
Example 4:
Date and time of 2 months ago
date --date="2 month ago"
Example 5:
Date and time of 10 days ago
date --date="10 day ago"
Note: These commands will display time or date irrespective of the current date and time.
5. Display Future Dates
This command can be used to display any specific future date and time. Here's the syntax below:
Example 1:
Date and time of upcoming particular week day.
Command:
$date --date="next tue" Output: Tue Oct 17 00:00:00 PDT 2017
Example 2:
Date and time after two days.
Command:
$date --date="2 day" Output: Fri Oct 13 00:05:52 PDT 2017
Example 3:
Date and time of next day.
Command:
$date --date="tomorrow" Output: Thu Oct 12 00:08:47 PDT 2017
Example 4:
Date and time after 1 year on the current day.
Command:
$date --date="1 year" Output: Thu Oct 11 00:11:38 PDT 2018
6. Set the System Date and Time
Use the -s or --set option to set the system date and time to a specific value.
Syntax:
date --set="date to be set"
Command:
$date Output:
Wed Oct 11 15:23:26 PDT 2017Command:
$date --set="Tue Nov 13 15:23:34 PDT 2018"
$dateOutput:
Tue Nov 13 15:23:34 PDT 2018
7. Display Date Strings from a File
--file or -f Option: This is used to display the date string present at each line of file in the date and time format.This option is similar to --date option but the only difference is that in --date we can only give one date string but in a file we can give multiple date strings at each line.
Syntax:
date --file=file.txt
$cat >> datefile
Sep 23 2018
Nov 03 2019Command:
$date --file=datefileOutput:
Sun Sep 23 00:00:00 PDT 2018
Sun Nov 3 00:00:00 PDT 2019
8. Display Last Modified Timestamp of a File
The -r option is used to display the last modified timestamp of a specified file.
Syntax:
date -r file.txt
We can modify the timestamp of a datefile by using touch command:
$touch datefile
$date -r datefile
Wed Oct 11 15:54:18 PDT 2017
//this is the current date and time
$touch datefile
//The timestamp of datefile is changed using touch command.
This was done few seconds after the above date command’s output.
$date -r datefile
Wed Oct 11 15:56:23 PDT 2017
//display last modified time of datefile
9. List of Format Specifiers Used with Date Command
The %d option is used to list of all format specifiers, adjoining to it different apprevations are used to specify the exact day, month or year. Have a look at the syntax below:
%D: Display date as mm/dd/yy.
%d: Display the day of the month (01 to 31).
%a: Displays the abbreviated name for weekdays (Sun to Sat).
%A: Displays full weekdays (Sunday to Saturday).
%h: Displays abbreviated month name (Jan to Dec).
%b: Displays abbreviated month name (Jan to Dec).
%B: Displays full month name(January to December).
%m: Displays the month of year (01 to 12).
%y: Displays last two digits of the year(00 to 99).
%Y: Display four-digit year.
%T: Display the time in 24 hour format as HH:MM:SS.
%H: Display the hour.
%M: Display the minute.
%S: Display the seconds.
Syntax:
date +%[format-option]
Examples:
1. Display Date in MM/DD/YY Format
date "+%D"
2. Display Date and Time in MM/DD/YY HH:MM:SS Format
date "+%D %T"
3. Display Date in YYYY-MM-DD Format
date "+%Y-%m-%d"
4. Display Date in YYYY/MM/DD Format
date "+%Y/%m/%d"
5. Display Full Date and Time with Day, Month, Date, Time, and Year
date "+%A %B %d %T %y"
Best Practices While Using the date Command in Linux
1. Ensure to cross-verify the changes that you're about to make with the date command.
2. Also, ensure that the format you're using is correct to display the correct desired timing or date. (you may also combine multiple specifiers for any custom format).
3. You can use date-based scripting to automate tasks such as file backup, log file rotations, or system maintenance tasks.
Conclusion
The date command in Linux is one of the most versatile and essential tool for managing date and time. Whether you're trying to set the system date, or looking to display specific date formats, or calculating past and future dates, it works like a charm. By using the options and format specifiers outlined in this, you can automate tasks, format time (in different ways), and ensure your Linux system's time settings are accurate.
