date (Unix)
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Unix date command
The Unix date command displays the time and date. The super-user can use it to set the system clock.
Contents
[hide]
1 Usage
2 Formatting
3 Options
4 Examples
5 Setting the date
6 See also
7 External links
[edit] 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. Specifically the GNU coreutils based command is much different than other POSIX implementations.
[edit] Formatting
To format a date provide a string beginning with + .
Format specifiers (format string starts with +) Specifier Description Values/Example
Day
%a weekday, abbreviated Thu
%A weekday, full Thursday
%d day of the month (dd), zero padded 23
%e day of the month (dd) 23
%j day of year, zero padded 001-366
%u day of week starting with Monday (1), i.e. mtwtfss 4
%w day of week starting with Sunday (0), i.e. smtwtfs 4
Week
%U week number Sunday as first day of week 01–53
%W week number Monday as first day of week 01–53
%V week of the year 01–53
Month
%m mm month 06
%h Mon Jun
%b Mon, locale's abbreviated Jun
%B locale's full month, variable length June
Year
%y yy two digit year 00–99
%Y ccyy year 2011
%g 2-digit year corresponding to the %V week number
%G 4-digit year corresponding to the %V week number
Century
%C cc century 00–99
Date
%D mm/dd/yy 06/23/11
%x locale's date representation (mm/dd/yy) 06/23/2011
%F %Y-%m-%d 2011-06-23
Hours
%l (Lowercase L) hour (12 hour clock) 12
%I (Uppercase I) hour (12 hour clock) zero padded 12
%k hour (24 hour clock) 12
%H hour (24 hour clock) zero padded 12
%p locale's upper case AM or PM (blank in many locales) PM
%P locale's lower case am or pm pm
Minutes
%M MM minutes 21
Seconds
%s seconds since 00:00:00 1970-01-01 UTC (Unix epoch) 1308831708
%S SS second 00–60
(The 60 is necessary to accommodate a leap second)
%N nanoseconds 000000000–999999999
Time
%r hours, minutes, seconds (12-hour clock) 12:21:48 PM
%R hours, minutes (24 hour clock) hh:mm e.g. 12:21
%T hours, minutes, seconds (24-hour clock) 12:21:48
%X locale's time representation (%H:%M:%S)
Date and Time
%c locale's date and time Sat Nov 04 12:02:33 EST 1989
Time zone
%z -zzzz RFC-822 style numeric timezone -0500
%Z time zone (e.g., EDT) nothing if no time zone is determinable EST
literals: %n newline %% percent %t horizontal tab
By default, date pads numeric fields with zeroes.
GNU date, but not BSD date, recognizes - (hyphen) do not pad the field and _ (underscore) pad the field with spaces between % and a numeric directive.
TZ Specifies the timezone, unless overridden by command line parameters. If neither is specified, the setting from /etc/localtime is used.
[edit] Options
-d, -de=string display time described by string, not now.
-e=datefile like de once for each line of datefile
-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 inhibites that.
-u Display or set the date in UTC (universal) time.
date [-u|--utc|--universal] [mmddHHMM[[cc]yy][[.SS]] The only valid option for this form specifies Coordinated Universal Time.
-u GMT ex: Sat Feb 5 14:49:42 GMT 2005
--utc, --universal Coordinated Universal Time local TZ Sat Feb 5 09:49:59 EST 2005
-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
--help
The Single Unix Specification (SUS) mandates only one option: -u, where the date and time is printed as if the timezone was UTC+0. Other Unix and Unix-like systems provide extra options.
[edit] 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 $DATE
20060704
To show the time in a different timezone, the TZ environment variable is read, Timezone types is found in /usr/share/zoneinfo
OLDTZ=$TZ
export TZ=GMT; echo "GMT: `date +\"%F %R (%Z)\"`"
GMT: 2008-10-31 12:30 (GMT)
export TZ=Europe/Stockholm; echo "Stockholm: `date +\"%F %R (%Z)\"`"
Stockholm: 2008-10-31 13:30 (CET)
export TZ=Asia/Kuala_Lumpur; echo "Kuala Lumpur: `date +\"%F %R (%Z)\"`"
Kuala Lumpur: 2008-10-31 20:30 (MYT)
export TZ=US/Central; echo "Dallas: `date +\"%F %R (%Z)\"`"
Dallas: 2008-10-31 07:30 (CDT)
export TZ=$OLDTZ
Other valid time strings
date +"%Y%m%d" -d sunday # GNU date
20060709
date +"%Y%m%d" -d last-sunday # GNU date
20060702
date +"%Y%m%d" -d last-week # GNU date
date -v -1m +"%Y%m%d" # BSD date
20060627
date +"%Y%m%d" -d last-month # GNU date
date -v -1w +"%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
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
[edit] 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.
Other Unix and Unix-like systems may set different options or date formats for date, for example, on some systems to set the current date and time to September 8, 2004 01:22 you type:
date --set="20040908 01:22"
[edit] See also
List of Unix programs
Unix time, i.e. number of seconds elapsed since midnight UTC of January 1, 1970 Epoch
time and date
Cron process for scheduling jobs to run on a given date.
[edit] 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.
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