date

date returns a system time specified by the user.

$ date
Tue Feb  6 12:42:38 EST 2018

This command returns the standard current time. With different options and parameters, it can also return other system time with different formats.

Date Formats

The syntax for using formatting options is:

$ date +[format]

The useful formatting options include:

%a  show abbreviated weekday name (eg. Mon)
%b  show abbreviated month name (eg. Jan)
%c  show date and time
%s  show the current seconds from 1970-01-01 00:00:00 UTC

Here are some examples of using formatting options:

$ date +%a%b
TueFeb

$ date +%s
1517939576

Example Flags

The syntax for using flags is:

$ date [-u|--utc|--universal] [MMDDhhmm[[CC]YY][.ss]]

-u shows the current system time in UTC. Note that the flags --utc and --universal have the same effects as -u.

$ date -u
Wed Feb 14 07:16:15 UTC 2018

-s sets the current system time to the string specified.

$ date -s "02/23/2018 02:23:00"
Fri Feb 23 02:23:00 EST 2018

-r FILE returns the last modified time of FILE.

$ date -r 398
Fri Feb 16 01:49:10 EST 2018

-f FILE returns the times within FILE. If the file TIMEFILE contained the following:

now
02/11/2018 02:23:00
01/01/2000 00:00:00

date -f TIMEFILE would create the following output:

$ date -f TIMEFILE
b 23 14:49:51 EST 2018
b 11 02:23:00 EST 2018
n 1 00:00:00 EST 2000

For more help, run

$ man date

to view the manual of this command.

Reference: https://linode.com/docs/tools-reference/tools/use-the-date-command-in-linux/