How to Use the Date Command in Linux

The date command displays the current date and time. It can also be used to display or calculate a date in a format you specify. The super-user (root) can use it to set the system clock.

Use the Linux date Command

When used without options, the date command displays the current system date and time, including the day of the week, month, time, timezone, and year:

date
Thu Apr 13 10:04:04 EDT 2017

To operate on a specific date, you can provide one with the -d flag:

date -d "1974-01-04"
Fri Jan  4 00:00:00 EST 1974

date has many display formatting options. Provide date with the formatting string by prefixing it with a plus sign:

date +"Week number: %V Year: %y"
Week number: 33 Year: 10

The format string is then output with each formatting token substituted by its value. %V is the formatting option to display the current week number, and %y represents the last two digits of the year.

Formatting Options

Run date --help to display a list of formatting options.

Here’s a small sample of the formatting tokens date supports:

For more details, run man date to view the entire man page.

Override the Timezone

By default, date uses the timezone defined in /etc/localtime. The environment variable TZ can be used to override this behavior. For example:

$ TZ=GMT date
Fri Aug 20 15:15:36 GMT 2010

Valid timezones are defined in /usr/share/zoneinfo/.

Examples

The following examples illustrate how you can use the date command to find the date and time at various points in time.

$ date -d now
Wed Aug 18 16:47:31 EDT 2010

$ date -d today
Wed Aug 18 16:47:32 EDT 2010

$ date -d yesterday
Tue Aug 17 16:47:33 EDT 2010

$ date -d tomorrow
Thu Aug 19 16:46:34 EDT 2010

$ date -d sunday
Sun Aug 22 00:00:00 EDT 2010

$ date -d last-sunday
Sun Aug 15 00:00:00 EDT 2010

Other valid date time strings include: last-week, next-week, last-month, next-month, last-year, and next-year.

Seconds from epoch

date has other surprising uses. For example, it can be used to convert a given date/time to Unix epoch time (seconds since 00:00:00, Jan 1, 1970) and back. The following example will show you the seconds from epoch to the current time:

$ date +%s
1282163756

Seconds from epoch to the provided date/time

$ date -d "1974-01-04" +"%s"
126507600

Convert epoch to a date

$ date -d "UTC 1970-01-01 126507600 secs"
Fri Jan  4 00:00:00 EST 1974

$ date -d @126507600
Fri Jan  4 00:00:00 EST 1974

Determine which day of the week a given date was

$ date -d "1974-01-04" +"%A"
Friday

Use date in Scripts and Commands

You can assign the output of date to a shell variable and then use it later in your scripts. For instance:

$ STARTTIME=`date`
$ echo $STARTTIME
Fri Aug 20 11:46:48 EDT 2010
$ sleep 5
$ echo $STARTTIME
Fri Aug 20 11:46:48 EDT 2010

You can also use date to create filenames that contain the current day:

tar cfz /backup-`date +%F`.tar.gz /home/caker/

This would tar and gzip the files in /home/caker/ into a filename called backup-2010-08-20.tar.gz.

Set the Date Manually from the Linux Terminal

If your system is running ntpd, and you’ve set your timezone correctly, you shouldn’t have to change this setting. However, if you find you need to set the system clock manually, use the --set option. In this example, we’re setting the date and time to 9:14pm on Thursday, April 13, 2017:

date --set="20170413 21:14"