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Using Date Command In Bash Script

date command on Linux can be used to display the current time and date. It is one of the most useful tools when working with bash script, as it is available on all Linux Systems. It allows you to display and configure the current date and time in different formats as needed.

Syntax

  date [OPTION]... [+FORMAT]
       date [-u|--utc|--universal] [MMDDhhmm[[CC]YY][.ss]]

According to the manual page of date command, it displays the current time in the given local format or sets the system date.

Using the date command

When we use the date command without any options, it will display the current system date and time:

~$ date
Thu Apr 18 20:51:45 CDT 2019

Here the results show the day of the week Thu, the day of the month Mar 21, time 21:03:35 , timezone (CDT) and year (2019).

Show the date in another TimeZone

To show the date at a different timezone, use the date and timezone.

date -- <TimeZone>

Let’s display the date in UTC Time Zone.

~$ date --utc
Fri Apr 19 01:52:35 UTC 2019

Relative Date using -date Option

Let’s get the date for next Wednesday.

~$ date --date="next wed"
Wed Apr 24 00:00:00 CDT 2019

Get Past Date

We can display the past date using the -date command.

Few Seconds Back

~$date --date='7 seconds ago'
Thu Apr 18 20:52:47 CDT 2019

One Day Back

~$ date --date="1 day ago"
Wed Apr 17 20:53:14 CDT 2019

Yesterday’s Date

~$date --date="yesterday"
Wed Apr 17 20:53:34 CDT 2019

#Yesterdays in YYMMDD format
~$  date --date="yesterday" +"%Y%m%d"
20190417

Get a Relative Date using the date command

This is another way to get an old date after adding 1 day to the existing date

~$ OLD_DATE=20190615
~$ NEW_DATE=$(date +%Y%m%d -d "$OLD_DATE +1 day")
~$ echo $NEW_DATE
20190616

Date in Custom Format

We can customize the format of the date by providing the +"format"option on the command line along with the date, as given in the below syntax. 

date +"format"
 $date +"%Y%m%d"
20190418

~$ date +"%Y-%m-%d %H:%M"
2019-04-18 20:57

~$ date +"%Y-%m-%d %H:%M:%S"
2019-04-18 20:57:56
 date +"%Y%m%d_%H%M%S"
20190418_205846

Commonly Used Control Sequences in Bash Script Date Command

Control SequenceDescription

%Y 		The year in the YYYY format. For example :
date +”%Y”
2019
%m The month in the MM format. For Example :
date +”%m”
04

%S 		The second is in the SS format. For Example:
date +”%S”
34
%HThe hour is in the HH format. For Example:
~$ date +”%H”
21
%MThe minute in the MM format. For Example:
~$ date +”%M”
14
%dThe day of the month in the DD format. For example:
~$ date +”%d”
18
%ZThe time zone abbreviation. For Example:
~$ date +”%Z”
CDT
%FThe full date in the YYYY-MM-DD format. This option is equal to %Y-%m-%d. For Example:
$ date +”%F”
2019-04-18
%TThe full time in the HH:MM: SS format. This option is equal to %H:%M:%S. ForExample:
~$ date +”%T”
21:14:13
%DIt displays the date in MM-DD-YY Format. For Example:
~$ date +”%D”
04/18/19

References

Date Manual Page

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