date (Unix)

Unix date command

The Unix date command displays and sets the time and date of the system clock. Setting the clock is restricted to the superuser.

The Single Unix Specification (SUS) mandates only one option: -u, where the date and time is printed or set in Coordinated Universal Time, as if the timezone were UTC+0. Other Unix and Unix-like systems provide extra options.

Displaying the date

Usage

With no options, the date command displays the current date and time, including the abbreviated day name, abbreviated month name, day of the month, the time separated by colons, the timezone name, and the year. For example:

$ date
Fri Jul 27 14:12:06 EDT 2007

Note that the implementation of the date command differs between Unix flavors (see references below). Specifically the GNU coreutils based command is much different than other POSIX implementations.

Formatting

To format a date, a parameter string beginning with a plus sign (+) is given. The formatting specifiers below are supported by most implementations.

Format specifiers (format string starts with +)

Specifier	Description	Values or example
Day
%a	weekday, abbreviated	Mon
%A	weekday, full	Monday
%d	day of the month, two digits, zero filled	08
%e	day of the month	8
%j	day of year, zero filled	001–366
%u	day of week from Monday to Sunday	1–7
%w	day of week from Sunday to Saturday	0–6
Week
%U	week number, Sunday as first day of week	00–53
%W	week number, Monday as first day of week	00–53
%V	ISO standard week of the year	01–53
Month
%m	two-digit month number	01–12
%h	month name, abbreviated	May
%b	month name, localised abbreviation	May
%B	locale's full month, variable length	May
Year
%y	two-digit year	00–99
%Y	four-digit year	2013
%g	two-digit year corresponding to the %V week number
%G	four-digit year corresponding to the %V week number
Century
%C	two century digits from year	00–99
Date
%D	mm/dd/yy	05/20/13
%x	locale's date representation	05/20/2013
%F	%Y-%m-%d	2013-05-20
Hours
%l	hour (12 hour)	9
%I	hour (12 hour), zero-filled	09
%k	hour (24 hour)	9
%H	hour (24 hour), zero-padded	09
%p	locale's upper case AM or PM (blank in many locales)	AM
%P	locale's lower case am or pm	am
Minutes
%M	two-digit minute number	25
Seconds
%s	seconds since 00:00:00 1970-01-01 UTC (Unix epoch)	1369041901
%S	two-digit second number	00–60 (Includes 60 to accommodate a leap second)
%N	nanoseconds	000000000–999999999
Time
%r	hours, minutes, seconds (12-hour clock)	09:25:01 AM
%R	hours, minutes (24 hour clock)	09:25
%T	hours, minutes, seconds (24-hour clock)	09:25:01
%X	locale's time representation	11:07:26 AM
Date and time
%c	locale's date and time	Sat Nov 04 12:02:33 EST 1989
Time zone
%z	RFC-822 style numeric time zone	-0500
%Z	time zone name; nothing if no time zone is determinable	EST, EDT

literals: %n newline      %% percent      %t horizontal tab

By default, date normally fills numeric fields with zeroes. GNU date, but not BSD date, recognizes a modifier between the per cent sign (%) and the format specifier:

• hyphen (-): do not fill the field
• underscore (_): pad the field with spaces

TZ Specifies the timezone, unless overridden by command line parameters. If neither is specified, the setting from /etc/localtime is used.

GNU date options

-d, --date=string display time described by string, not now. It is a human readable format such as "next Thursday" or "1 month ago". A date string may contain items indicating calendar date, time of day, time zone, day of week, relative time, relative date, and numbers. This is also known as relative GNU date formats. Here are a few examples of relative date:

date --date="1 days ago"
date --date="yesterday"
date --date='10 month ago'
date --date='2 hour ago'
date --date='Second Friday'

-e=datefile like de once for each line of datefile

-ITIMESPEC, --iso-8601[=TIMESPEC] output date/time in ISO 8601 format. TIMESPEC=date for date only, hours, minutes, or seconds for date and time to the indicated precision.

--iso-8601 without TIMESPEC defaults to `date'.

-R, --rfc-822 output RFC-822 compliant date string, example: Wed, 16 Dec 2009 15:18:11 +0100

Examples

date "+%m/%d/%y" 
7/4/06

date "+%Y%m%d"
20060704

To assign the time to a variable

START=`date '+%r'`
echo $START
03:06:02 PM
sleep 5
echo $START
03:06:02 PM

N.B. the variable has the time when it was assigned.

Yesterday assigned to variable

DATE=$(date -d yesterday +"%Y%m%d")
echo $DATE
20060704

The TZ environment variable specifies the timezone. Valid values are in /usr/share/zoneinfo

TZ=GMT; echo "GMT: `date +\"%R (%Z)\"`"
GMT: 12:30 (GMT)
TZ=Europe/Stockholm; echo "Stockholm: `date +\"%R (%Z)\"`"
Stockholm: 13:30 (CET)
TZ=Asia/Kuala_Lumpur; echo "Kuala Lumpur: `date +\"%R (%Z)\"`"
Kuala Lumpur: 20:30 (MYT)
TZ=US/Central; echo "Dallas: `date +\"%R (%Z)\"`"
Dallas: 07:30 (CDT)

Converting between timezones Example: What time is it in Moscow when it will be 17:35 in Los Angeles

$ TZ=Europe/Moscow date "+%F %R (%Z%z)" -d 'TZ="America/Los_Angeles" 17:35'
2013-03-22 04:35 (MSK+0400)

Other valid time strings

date +"%Y%m%d" -d sunday # GNU date
date -v +sun +"%Y%m%d" # BSD date
20060709

date +"%Y%m%d" -d last-sunday # GNU date
date -v -sun +"%Y%m%d" # BSD date
20060702

date +"%Y%m%d" -d last-week # GNU date
date -v -1w +"%Y%m%d" # BSD date
20060627

date +"%Y%m%d" -d last-month # GNU date
date -v -1m +"%Y%m%d" # BSD date
20060604

date +"%Y%m%d" -d last-year # GNU date
date -v -1y +"%Y%m%d" # BSD date
20050704

date +"%Y%m%d" -d next-week # GNU date
date -v 1w +"%Y%m%d" # BSD date
20060711

date +"%Y%m%d" -d next-month # GNU date
date -v 1m +"%Y%m%d" # BSD date
20060804

date +"%Y%m%d" -d next-year # GNU date
date -v 1y +"%Y%m%d" # BSD date
20070704

date +"%Y%m%d" -d "2 days ago" # GNU date
date -v -2d +"%Y%m%d" # BSD date
20060702

date +"%Y%m%d" -d "2 months ago" # GNU date
date -v -2m +"%Y%m%d" # BSD date
20060504

date +"%Y%m%d" -d "2 years ago" # GNU date
date -v -2y +"%Y%m%d" # BSD date
20040704

To show the time in seconds since 1970-01-01 (Unix epoch):

date +"%s" -d "Fri Apr 24 13:14:39 CDT 2009"
1240596879

To convert Unix epoch time (seconds since 1970-01-01) to a human readable format:

date -d "UTC 1970-01-01 1240596879 secs"
Fri Apr 24 13:14:39 CDT 2009

Or:

date -ud @1000000000
Sun Sep  9 01:46:40 UTC 2001

Output based on locale

> export LC_ALL=""
> date
Mon Apr 23 20:47:18 EDT 2012
> export LC_ALL="en_US.UTF-8"
> date
Mon Apr 23 20:46:59 EDT 2012
> export LC_ALL="de_DE"
> date
Mo 23. Apr 20:47:05 EDT 2012
> export LC_ALL="danish"
> date
man apr 23 20:48:09 EDT 2012

Setting the date

The XSI extension to the SUS specifies that the date command can also be used to set the date. The new date is specified as an option to date in the format MMddhhmm[[cc]yy], where MM specifies the two-digit numeric month, dd specifies the two-digit numeric day, hh specifies the two-digit numeric hour, mm specifies the two-digit numeric minutes. Optionally cc specifies the first two digits of the year, and yy specifies the last two digits of the year.

The date command from GNU Coreutils (often used on Linux) allows another method with a different format,

• for example to set the date and time to
  • March 26, 2013 18:00:

date --set="20130426 18:00"

Options

-s, --set=string set time described by string

-n don't synchronize the clocks on groups of machines using the utility timed(8). By default, if timed is running, date will set the time on all of the machines in the local group. -n inhibits that.

See also

• List of Unix programs
• Unix time, i.e. number of seconds elapsed since midnight UTC of January 1, 1970 Epoch
• DATE DOS command
• TIME DOS command
• Cron process for scheduling jobs to run on a given date.

External links

• date: write the date and time – Commands & Utilities Reference, The Single UNIX® Specification, Issue 7 from The Open Group
• date(1): print or set the system date and time – Linux User Commands Manual
• date(1) – FreeBSD General Commands Manual
• UNIX date command examples.