date handling

the date and time in Unix.

Syntax

date [-a] [-u] [-s datestr]

-a	Slowly adjust the time by sss.fff seconds (fff represents fractions of a second). This adjustment can be positive or negative. The system's clock will be sped up or slowed down until it has drifted by the number of seconds specified. Only the super-user may adjust the time.
-u	Display (or set) the date in Greenwich Mean Time (GMT-universal time), bypassing the normal conversion to (or from) local time.
-s datestr	Sets the time and date to the value specfied in the datestr. The datestr may contain the month names, timezones, 'am', 'pm', etc. See examples for an example of how the date and time can be set.

Examples

date - Would list the date and time of the server. Below is an example of the output.

Thu Feb 8 16:47:32 MST 2001

date -s "11/20/2003 12:48:00" - Set the date to the date and time shown.
date '+DATE: %m/%d/%y%nTIME:%H:%M:%S' - Would list the time and date in the below format:

DATE: 02/08/01
TIME:16:44:55

Syntax to specify format
date +FORMAT

Task: Display date in mm-dd-yy format

Type the command as follows:
$ date +"%m-%d-%y"
Output:

02-27-07

Turn on 4 digit year display:
$ date +"%m-%d-%Y"
Just display date as mm/dd/yy format:
$ date +"%D"

Task: Display time only

Type the command as follows:
$ date +"%T"
Output:

19:55:04

Display locale’s 12-hour clock time
$ date +"%r"
Output:

07:56:05 PM

Display time in HH:MM format:
$ date +"%H-%M"

How do I save time/date format to a variable?

Simply type command as follows at a shell prompt:
$ NOW=$(date +"%m-%d-%Y")
To display a variable use echo / printf command:
$ echo $NOW
Sample shell script:

#!/bin/bash
NOW=$(date +"%m-%d-%Y")
FILE="backup.$NOW.tar.gz"
# rest of script

Complete list of FORMAT control characters supported by date command

FORMAT controls the output.It can be the combination of any one of the following:

%%

a literal %

%a

locale's abbreviated weekday name (e.g., Sun)

%A

locale's full weekday name (e.g., Sunday)

%b

locale's abbreviated month name (e.g., Jan)

%B

locale's full month name (e.g., January)

%c

locale's date and time (e.g., Thu Mar 3 23:05:25 2005)

%C

century; like %Y, except omit last two digits (e.g., 21)

%d

day of month (e.g, 01)

%D

date; same as %m/%d/%y

%e

day of month, space padded; same as %_d

%F

full date; same as %Y-%m-%d

%g

last two digits of year of ISO week number (see %G)

%G

year of ISO week number (see %V); normally useful only with %V

%h

same as %b

%H

hour (00..23)

%I

hour (01..12)

%j

day of year (001..366)

%k

hour ( 0..23)

%l

hour ( 1..12)

%m

month (01..12)

%M

minute (00..59)

%n

a newline

%N

nanoseconds (000000000..999999999)

%p

locale's equivalent of either AM or PM; blank if not known

%P

like %p, but lower case

%r

locale's 12-hour clock time (e.g., 11:11:04 PM)

%R

24-hour hour and minute; same as %H:%M

%s

seconds since 1970-01-01 00:00:00 UTC

%S

second (00..60)

%t

a tab

%T

time; same as %H:%M:%S

%u

day of week (1..7); 1 is Monday

%U

week number of year, with Sunday as first day of week (00..53)

%V

ISO week number, with Monday as first day of week (01..53)

%w

day of week (0..6); 0 is Sunday

%W

week number of year, with Monday as first day of week (00..53)

%x

locale's date representation (e.g., 12/31/99)

%X

locale's time representation (e.g., 23:13:48)

%y

last two digits of year (00..99)

%Y

year

%z

+hhmm numeric timezone (e.g., -0400)

%:z

+hh:mm numeric timezone (e.g., -04:00)

%::z

+hh:mm:ss numeric time zone (e.g., -04:00:00)

%:::z

numeric time zone with : to necessary precision (e.g., -04, +05:30)

%Z

alphabetic time zone abbreviation (e.g., EDT)