Master the Linux date Command: Display, Format, and Set Dates

1. Display the current date and time

Running date without any options prints the current weekday, month, day, time, timezone and year, e.g.:

[root@server1 ~]# date
Mon May 24 14:50:31 CST 2021

2. Show UTC (Coordinated Universal Time)

Use the -u flag to display the time in UTC:

[root@server1 ~]# date -u
Mon May 24 06:51:21 UTC 2021

3. Display a specific date using a string

The --date option accepts a date string and prints the corresponding date without changing the system clock:

[root@server1 ~]# date --date="5/20/2021 13:14"
Thu May 20 13:14:00 CST 2021

4. Query past dates

You can ask for dates relative to now, such as "9 days ago", "3 months ago" or "2 years ago":

[root@server1 ~]# date --date="9 days ago"
Sat May 15 14:56:47 CST 2021

[root@server1 ~]# date --date="3 months ago"
Wed Feb 24 14:57:29 CST 2021

[root@server1 ~]# date --date="2 years ago"
Fri May 24 15:02:40 CST 2019

5. Query future dates

Similarly, you can request dates like "tomorrow", "next week", "3 weeks", "4 months" or "2 years":

[root@server1 ~]# date --date="tomorrow"
Tue May 25 14:58:49 CST 2021

[root@server1 ~]# date --date="next week"
Mon May 31 14:59:27 CST 2021

[root@server1 ~]# date --date="3 weeks"
Mon Jun 14 15:00:11 CST 2021

[root@server1 ~]# date --date="4 months"
Fri Sep 24 15:01:42 CST 2021

[root@server1 ~]# date --date="2 years"
Wed May 24 15:03:32 CST 2023

6. Formatting output with options

The date command supports a wide range of format specifiers. Some common ones are: %D – month/day/year (e.g., 05/24/21) %Y – four‑digit year (e.g., 2021) %m – month number (01‑12) %B – full month name (e.g., January) %b – abbreviated month name (e.g., Jan) %d – day of month (01‑31) %j – day of year (001‑366) %u – weekday number (1‑7, Monday=1) %A – full weekday name (e.g., Friday) %a – abbreviated weekday name (e.g., Fri) %H – hour (00‑23) %I – hour (01‑12) %M – minute (00‑59) %S – second (00‑60)

To use a format, pass it after a plus sign, for example:

date "+%Y/%m/%d"
2021/05/24

Or to print a full readable timestamp:

date "+%A %B %d %Y %T"
Monday May 24 2021 15:24:07

7. Setting the system date and time

With the --set option you can change the system clock. For example, to set the date to 25 June 2021 11:15 AM:

[root@server1 ~]# date --set="20210625 11:15"
Fri Jun 25 11:15:00 CST 2021

8. Using date in shell scripts

Storing the command output in a variable is useful for generating log file names or timestamps. Example script:

#!/bin/bash
LOGFILE=/tmp/logs-$(date +%d-%m-%Y_%T)

echo "##Check Cluster for Failed Resources##" >> $LOGFILE
crm_mon -1 -rf | grep FAILED >> $LOGFILE

echo -e "

" >> $LOGFILE

echo "##Check Cluster for Stopped Resources##" >> $LOGFILE
crm_mon -1 -rf | grep -i STOPPED >> $LOGFILE

echo -e "

" >> $LOGFILE

This demonstrates how date can provide dynamic timestamps for log management and other automation tasks.