Date _____ %b month, %h Mon, %a dow, %m mm, %d dd, %I hh, %M minutes ; last month, last Thursday 221231

Display or set date and time

Green
options
not BSD
not mac os

date [-nu] [-r file] [ +format]

date [-jnRu] [-d ^x⃓y datestring| --date= datestring] [-r seconds] [-t west] [-v[+|-]val[ymwdHMS]] … [-f | fmt date | --file=fileOfDates [[[mm]dd]HH]MM[[cc]yy][.ss]] [+format]

date -d n -t minutes_west date [[[[[cc]yy]mm]dd]hh]mm[.ss] set system time 

The default format is: "%a %b %e %H:%M:%S %Z %Y"
sample output: Sat Dec 31 18:09:28 EST 2021

Useful forms:
export TODAY=`date +%y%m%d`
quotes are unneeded as format does not include space etc echo $TODAY 221231
export yymmdd=`date +%y%m%d` echo $yymmdd 130915
export LOG=`date +log/%y%m%d.%H%M` echo $LOG log/211231.1859 myscript1 >> $LOG myscript2 >> $LOG
export title=`date +"Report Date: %m/%d %H:%M"` Report Date: 07/20 18:56
echo `date "+%Y-%m-%d %H:%M:%S"` 2018-12-31 23:59:59 (Similar to linux syslog formats.)
touch `date +"%Y-%m-%d %H:%M:%S"` creates files named yy-mm-dd and hh:mm:ss
I forget why this is interesting! .

format codes
(arranged by function, not alphabetically, composite formats)
N.B. If used in crontab command fields, % must be escaped.
locale: order of date items vary
as well as spellings as per language.
Examples:
LC_ALL=C > date Wed Jun 22 13:18:10 EDT 2016 > export LC_ALL=es_ES # use Spanish (Español) > date miércoles, 22 de junio de 2016, 13:39:34 EDT
%m mm month (01…12)
to blank pad ie ' 1, 2, 3' vs '01,02,03' ?? ) sed s/0([[:digit:]])/ $1/
%b abbreviated month (Jan…Dec) %h (same as:%b)
%B full month, variable length (January…December)

%d dd (01…31), %e ( 1…31)

%C cc century (00…99) %y yy two digit year (00…99)
%Y ccyy year (1970)
%g 2-digit year corresponding to the %V week number %G 4-digit

%F %Y-%m-%d (2013-02-24)

%D mm/dd/yy %x mm/dd/yy
hours
%I (01…12) %H (00…23)
%l^† (1…12) %k (0…23)

%p AM or PM upper case (blank in many locales)   %P am or pm lower case

%M MM minutes (00…59)

%S SS second (00…60) The 60 is necessary to accommodate a leap second

24-hour: %R (23:59), %T HH:mm:ss ( 11:53:41 )
12-hour: %r (11:26:20 AM ) %X %H:%M:%S (11:56:05 AM)
%N nanoseconds ^† since last second (000000000..999999999)
(on mac OS use gdate )
     Use sed to restrict the output to milliseconds:
date +%S.%N|sed "s/......$//" 26.123 %c date and time
(Sat Nov 04 12:02:33 EST 1989 )
%j day of year (001…366)
%u day of week (1…7); 7 represents Sunday mtwtfss
%w                    (0…6); 0 represents Sunday smtwtfs
%a abbreviated weekday (Sun…Sat)
%A full weekday, variable length (Sunday…Saturday)
%U week number Sunday as first day of week (00…53)
%W week number Monday as first day of week (00…53)    %V (01…53)
%z -zzzz RFC-822 style numeric timezone (-0400)
%:z +hh:mm numeric timezone ( -04:00)
%::z +hh:mm:ss numeric time zone ( -04:00:00)

%:::z numeric time zone with : to necessary precision (-04, +05:30)
%Z time zone (EDT) nothing if no time zone is determinable
$TZ timezone, unless overridden by command line parameters.
Default: the setting from /etc/localtime is used.
on macBookPro:      > hexdump -e '"%_p"' -s 0x4DB -n 7 /etc/localtime      EDT.EST On Real-World-Systems.com      hexdump -e '"%_p"' /etc/localtime |tail -2      .MST7MDT,M3.2.0,M1*      > echo $TZ      America/Boise      > date      Wed Mar 27 18:36:50 MDT 2019      export TZ=US/Eastern      > echo $TZ      US/Eastern      > date      Wed Mar 27 20:37:00 EDT 2019

%s seconds since 00:00:00 1970-01-01 UTC i.e. epoch
To convert %s value like 1212642879
use date -d "1970-01-01 1212642879 sec utc" Not mac

1264434947 was Mon Jan 25 10:55:57 EST 2010 1402410634 was Tue Jun 10 10:29:44 EDT 2014
Example usage:
export login_s=`date +%s` # include this in .profile

# ~/.bash_logout echo " $(((`date +%s` - $login_s)/60)) minutes" sleep 3

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

By default, date pads numeric fields with zeroes.
GNU (not BSD) date recognizes modifiers between % and a numeric:
- (hyphen) do not pad the field _ (underscore) pad the field with spaces
examples:
%_H == %k       %-m/%-d/%y 1/2/50

Options

`-d string -de=string`	Display time described by `string` Including some "humand readable" strings like `last Thursday` and `last month` date -d "2010/12/31" Fri Dec 31 00:00:00 EST 2010 date -d "12/31/2010" Fri Dec 31 00:00:00 EST 2010 date -d "2010-12-31 23:58:57" Fri Dec 31 23:58:57 EST 2010 date -d "23:58:57 12/31/2010" Fri Dec 31 23:58:57 EST 2010 date -d "12/31/2010 23:58:57" Fri Dec 31 23:58:57 EST 2010 date -d "12/31/2010 23 sec" Fri Dec 31 00:00:23 EST 2010 To convert seconds (for example 1212642879) use: `> date -d "1970-01-01 1212642879 sec utc" Thu Jun 5 01:14:39 EDT 2008`
`-e=datefile`	like `-de` once for each line of `datefile`
BSD(Mac OS X):
`-f fmt_str idate [ +fmt]`	Output `idate` Default `fmt_str` is `[[[mm]dd]HH]MM[[cc]yy][.ss]`
`-j` with `-f`	Don't set date and time seconds from the Epoch. ( i.e. `Dec 31 19:00:00 EST 1969` i.e. 01/01/70 00:00:00)
`-r file --reference=file`	output modification date/time of `file` > date -r 0test Thu Aug 19 18:05:09 EDT 2010 > date -r arp.1.html +"%y%m%d_%H%M" 140630_1810
`-v [±]valuem\|d\|H\|M\|S\|w -v{±]name`	Output the current date set as per `value`. Suffix is required (without preceeding space) and for `y` the `value` must be in the range of 80-38 or 1980-2038, otherwise return code will be 1. `name` is a case in-sensitive, 3 character or longer week_day or month . If `value` is preceded with a `+` or `-` the date is adjusted forwards or backwards. If a `name` is used with a sign, the date will be adjusted forwards (or backwards) to the next (previous) date that matches the given week day or month. If the given week day or month is the same as the current one no adjustment is made. Attempting to set or adjust a date to an invalid day fails with return code of 1. For example: `-v 31d`, for months having less than 31 days. To minimize this problem, set the minutes first then the day, for example: `-v 12m -v 31d` Adjusting by `m`onths is ambiguous because months have varying numbers of days. Adjusting the month on the 31^st, if the target month is shorter than the present one, will result in using the last day of the target month. For example, using `-v +1m` on May 31 will adjust the date to June 30, Daylight Saving Time Daylight savings time considerations are ignored. when a date is set to a value or adjusted in units greater than hours, Daylight saving time is honor with Adjustments in units of hours or less . For example: If the current date is March 26, 00:30 and the DST adjustment means the clock goes forward at 01:00 to 02:00, using `-v +1H` will adjust the date to March 26, 02:30. if the date is October 29, 00:30 and the DST adjustment means that the clock goes back at 02:00 to 01:00, `-v +3H` is necessary to reach October 29, 02:30. If the date is adjusted to a value that does not exist (due to day light savings time, for example March 26, 01:30 BST 2000 in the Europe/London timezone), the date will be adjusted forwards in units of one hour until it reaches a valid time If the date is adjusted to a value that occurs twice (for example October 29, 01:30 2000), the resulting timezone will be set so that the date matches the earlier of the two times. Multiple `-t`s are permitted.
`-u --utc --universal` [`MMDDhhmm[[CC]YY][.ss]`]	Sun Jun 27 21:56:05 UTC 2021 aka GMT ex: `Sat Feb 5 14:49:42 GMT 2005`
`-I[precision] --iso-8601[=precision]`	output in ISO 8601 format. `precision` : `date` \| `hours` \| `minutes` \| `seconds` \| `ns` > date --iso-8601 2010-08-23 > date --iso-8601=hours 2010-08-23T21-0400 > date --iso-8601=minutes 2010-08-23T21:05-0400 > date --iso-8601=seconds 2010-08-23T21:05:53-0400 > date --iso-8601=ns 2010-08-23T21:05:53,632672872-04:00
`-R --rfc-822`	output RFC-822 compliant date string Sun, 23 Aug 2010 21:53:18 -0400
`-s string --set=string`	set the system the clock to `string` Example: `date -s "2010-12-31 23:59:00"`
`-d dst`	Set kernel value for daylight saving time. 
`-n`	No synchroniztion of clocks on groups of machines using `timed`. Default: if `timed` is running, `date` will set the time on all of the machines in the local group, `-n` inhibites that.
`--help`	display help and exit
`--version`	output version information and exit

java script functions From w3schools.com

according to
UTC (aka GMT)
date object is local
getMonth() 0-11 getUTCMonth()
getDate() day of the month ( 1-31) getUTCDate()
getFullYear() year yyyy getUTCFullYear()
getHours() 0-23 getUTCHours()
getMinutes() 0-59 getUTCMinutes()
getSeconds() 0-59 getUTCSeconds()
getMilliseconds() 0-999 getUTCMilliseconds()
getDay() of the week ( 0-6) getUTCDay()
getTime() milliseconds since 1/1/1970 00:00
getTimezoneOffset() minutes between UTC and local
getYear() Deprecated. Use the getFullYear() method
parse() number of milliseconds since 1/1/1970 00:00 of date string
set portions of a date object
setFullYear() YYYY setUTCFullYear()
setMonth() setUTCMonth()
setDate() day of the month setUTCDate()
setHours() setUTCHours()
setMinutes() setUTCMinutes()
setSeconds() setUTCSeconds()
setMilliseconds() setUTCMilliseconds()
setTime() Sets a date and time
by adding or subtracting milliseconds to/from 1/1/1970 00:00
setYear() Deprecated. Use the setFullYear() method
formatting to string
toString() `Sat Aug 04 2012 17:09:15 GMT-0400 (EDT)` toLocaleString() `Sat Aug 4 17:08:41 2012`
Really! YYYY last
toISOString() `2012-08-04T21:03:51.449Z`
toJSON()
JavaScript Object Notation `2012-08-04T20:27:42.419Z`
toUTCString() `Sat, 04 Aug 2012 21:32:18 GMT`
toDateString() `Sat Aug 04 2012` toLocaleDateString() `08/04/2012`
toTimeString() `17:14:24 GMT-0400 (EDT)` toLocaleTimeString() `17:06:00`
toGMTString() Deprecated. Use the toUTCString() method
valueOf() primitive value of a Date object
`1344116221551`
UTC(`yyyy,mm,dd`) number of milliseconds in `yyyy,mm,dd`
since 00:00 1/1/1970
according to universal time
`1333065600000`

The default `format` is:	`"%a %b %e %H:%M:%S %Z %Y"`
sample output:	`Sat Dec 31 18:09:28 EST 2021`

Useful forms:
export TODAY=`date +%y%m%d` quotes are unneeded as format does not include space etc	`echo $TODAY 221231`
export yymmdd=`date +%y%m%d`	`echo $yymmdd 130915`
export LOG=`date +log/%y%m%d.%H%M`	`echo $LOG log/211231.1859 myscript1 >> $LOG myscript2 >> $LOG`
export title=`date +"Report Date: %m/%d %H:%M"`	`Report Date: 07/20 18:56`
echo `date "+%Y-%m-%d %H:%M:%S"`	`2018-12-31 23:59:59` (Similar to linux syslog formats.)
touch `date +"%Y-%m-%d %H:%M:%S"`	creates files named `yy-mm-dd and hh:mm:ss` I forget why this is interesting! .

`format` codes (arranged by function, not alphabetically, composite formats) N.B. If used in `crontab` command fields, `%` must be escaped.	locale: order of date items vary as well as spellings as per language. Examples: LC_ALL=C > date Wed Jun 22 13:18:10 EDT 2016 > export LC_ALL=es_ES # use Spanish (Español) > date miércoles, 22 de junio de 2016, 13:39:34 EDT
`%m` mm month (`01`…`12`) to blank pad ie ' 1, 2, 3' vs '01,02,03' ?? ) sed s/0([[:digit:]])/ $1/ `%b` abbreviated month (`Jan`…`Dec`) `%h` (same as:`%b`) `%B` full month, variable length (`January…December`)
`%d` dd (`01`…31), `%e` ( `1…31`)
`%C` cc century (`00…99`) `%y` yy two digit year (`00…99`) `%Y` ccyy year (`1970`)
`%g` 2-digit year corresponding to the `%V` week number `%G` 4-digit
`%F %Y-%m-%d` (`2013-02-24`)

`%D` mm/dd/yy	`%x` mm/dd/yy
hours `%I` (`01…12`) `%H` (`00…23`) `%l`^† (`1…12`) `%k` (`0…23`)
`%p` `AM` or `PM` upper case (blank in many locales) `%P` `am` or `pm` lower case
`%M` MM minutes (`00…59`)
`%S` SS second (`00…60`) The 60 is necessary to accommodate a leap second
24-hour: `%R` (`23:59`), `%T` HH:mm:ss ( `11:53:41` ) 12-hour: `%r` (`11:26:20 AM` ) `%X` %H:%M:%S (`11:56:05 AM`)
`%N` nanoseconds ^† since last second (`000000000..999999999`) (on mac OS use `gdate` ) Use `sed` to restrict the output to milliseconds: `date +%S.%N\|sed "s/......$//"` 26.123	`%c` date and time (`Sat Nov 04 12:02:33 EST 1989` )
`%j` day of year (`001…366`)
`%u` day of week (`1…7`); 7 represents Sunday mtwtfss `%w` (`0…6`); 0 represents Sunday smtwtfs	`%a` abbreviated weekday (`Sun…Sat`) `%A` full weekday, variable length (`Sunday…Saturday`)
`%U` week number Sunday as first day of week (`00…53`)
`%W` week number Monday as first day of week (`00…53`) `%V` (`01…53`)
`%z` -zzzz RFC-822 style numeric timezone (`-0400`)
`%:z` +hh:mm numeric timezone ( `-04:00`)
`%::z` +hh:mm:ss numeric time zone ( `-04:00:00`)
`%:::z` numeric time zone with : to necessary precision (`-04, +05:30`)
`%Z` time zone (`EDT`) nothing if no time zone is determinable
`$TZ` timezone, unless overridden by command line parameters. Default: the setting from `/etc/localtime` is used. on macBookPro: > hexdump -e '"%_p"' -s 0x4DB -n 7 /etc/localtime EDT.EST On Real-World-Systems.com hexdump -e '"%_p"' /etc/localtime \|tail -2 .MST7MDT,M3.2.0,M1* > echo $TZ America/Boise > date Wed Mar 27 18:36:50 MDT 2019 export TZ=US/Eastern > echo $TZ US/Eastern > date Wed Mar 27 20:37:00 EDT 2019
`%s` seconds since `00:00:00 1970-01-01 UTC` i.e. epoch To convert `%s` value like 1212642879 use `date -d "1970-01-01 1212642879 sec utc"` Not mac 1264434947 was Mon Jan 25 10:55:57 EST 2010 1402410634 was Tue Jun 10 10:29:44 EDT 2014 Example usage: export login_s=`date +%s` # include this in .profile # ~/.bash_logout echo " $(((`date +%s` - $login_s)/60)) minutes" sleep 3
literals: `%n` newline ; `%%` percent; `%t` horizontal tab By default, date pads numeric fields with zeroes. GNU (not BSD) date recognizes modifiers between `%` and a numeric: - (hyphen) do not pad the field _ (underscore) pad the field with spaces examples: `%_H == %k` `%-m/%-d/%y 1/2/50`

set portions of a date object
		according to UTC (aka GMT) date object is local
getMonth()	0-11	getUTCMonth()
getDate()	day of the month ( 1-31)	getUTCDate()
getFullYear()	year yyyy	getUTCFullYear()
getHours()	0-23	getUTCHours()
getMinutes()	0-59	getUTCMinutes()
getSeconds()	0-59	getUTCSeconds()
getMilliseconds()	0-999	getUTCMilliseconds()
getDay()	of the week ( 0-6)	getUTCDay()
getTime()	milliseconds since 1/1/1970 00:00
getTimezoneOffset()	minutes between UTC and local
getYear()	Deprecated. Use the getFullYear() method
parse()	number of milliseconds since 1/1/1970 00:00 of date string
setFullYear()	YYYY	setUTCFullYear()
setMonth()		setUTCMonth()
setDate()	day of the month	setUTCDate()
setHours()		setUTCHours()
setMinutes()		setUTCMinutes()
setSeconds()		setUTCSeconds()
setMilliseconds()		setUTCMilliseconds()
setTime()	Sets a date and time by adding or subtracting milliseconds to/from 1/1/1970 00:00
setYear()	Deprecated. Use the setFullYear() method
formatting to string
toString()	`Sat Aug 04 2012 17:09:15 GMT-0400 (EDT)`	toLocaleString()	`Sat Aug 4 17:08:41 2012` Really! YYYY last
toISOString()	`2012-08-04T21:03:51.449Z`
toJSON() JavaScript Object Notation	`2012-08-04T20:27:42.419Z`
toUTCString()	`Sat, 04 Aug 2012 21:32:18 GMT`
toDateString()	`Sat Aug 04 2012`	toLocaleDateString()	`08/04/2012`
toTimeString()	`17:14:24 GMT-0400 (EDT)`	toLocaleTimeString()	`17:06:00`
toGMTString()	Deprecated. Use the toUTCString() method
valueOf()	primitive value of a Date object `1344116221551`
UTC(`yyyy,mm,dd`)	number of milliseconds in `yyyy,mm,dd` since 00:00 1/1/1970 according to universal time `1333065600000`

Display or set date and time

Options

Daylight Saving Time

see also