Linux Date-Time Shell Script Syntax

Linux Date-Time Shell Script Syntax

BASH Shell, FreeBSD, LiNUX, Mac-OSX, UNiX

How do I format the date to display on the screen on for my shell scripts as per my requirements on Linux or Unix like operating systems?

You need to use the standard date command to format date or time in Linux or Unix shell scripts. You can use the same command with the shell script. This page shows how to format date in Linux or Unix-based system.

Linux Syntax Format Date Display On Screen

The syntax is as follows for the GNU/date and BSD/date command:

date +FORMAT
date +"%FORMAT"
date +"%FORMAT%FORMAT"
date +"%FORMAT-%FORMAT"

An operand with a leading plus (+) sign signals a user-defined format string which specifies the format in which to display the date and time. The following examples are tested on GNU/Linux, Apple OS X Unix, and FreeBSD unix operating system.

Task: Display date in mm-dd-yy format

Open a terminal and type the following date command:

$ date +"%m-%d-%y"

Sample outputs:

02-27-07

To 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 following command:

$ date +"%T"

Sample outputs:

19:55:04

To display locale’s 12-hour clock time, enter:

$ date +"%r"

Sample outputs:

07:56:05 PM

To display time in HH:MM format, type:

$ date +"%H-%M"

Sample outputs:

00-50

How-To save time/date format in shell variables?

Simply type the following command at the shell prompt:

$ NOW=$(date +"%m-%d-%Y")

To display a variable use echo / printf command:

$ echo $NOW

A sample shell script

#!/bin/bash NOW=$(date +"%m-%d-%Y") FILE="backup.$NOW.tar.gz" echo "Backing up data to /nas42/backup.$NOW.tar.gz file, please wait..." # rest of script # tar xcvf /nas42/backup.$NOW.tar.gz /home/ /etc/ /var

A complete list of FORMAT control characters supported by the GNU/date command

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

%FORMAT String	Description
%%	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)

A complete list of FORMAT control characters supported by the BSD/date command

The following works on Apple OS X, FreeBSD and BSD version of the date command:

%A	is replaced by national representation of the full weekday name.
%a	is replaced by national representation of the abbreviated weekday name.
%B	is replaced by national representation of the full month name.
%b	is replaced by national representation of the abbreviated month name.
%C	is replaced by (year / 100) as decimal number; single digits are preceded by a zero.
%c	is replaced by national representation of time and date.
%D	is equivalent to “%m/%d/%y”.
%d	is replaced by the day of the month as a decimal number (01-31).
%E* %O*	POSIX locale extensions. The sequences %Ec %EC %Ex %EX %Ey %EY %Od %Oe %OH %OI %Om %OM %OS %Ou %OU %OV %Ow %OW %Oy are supposed to provide alternate representations. Additionally %OB implemented to represent alternative months names (used standalone, without day mentioned).
%e	is replaced by the day of the month as a decimal number (1-31); single digits are preceded by a blank.
%G	is replaced by a year as a decimal number with century. This year is the one that contains the greater part of the week (Monday as the first day of the week).
%g	is replaced by the same year as in “%G”, but as a decimal number without century (00-99).
%H	is replaced by the hour (24-hour clock) as a decimal number (00-23).
%h	the same as %b.
%I	is replaced by the hour (12-hour clock) as a decimal number (01-12).
%j	is replaced by the day of the year as a decimal number (001-366).
%k	is replaced by the hour (24-hour clock) as a decimal number (0-23); single digits are preceded by a blank.
%l	is replaced by the hour (12-hour clock) as a decimal number (1-12); single digits are preceded by a blank.
%M	is replaced by the minute as a decimal number (00-59).
%m	is replaced by the month as a decimal number (01-12).
%n	is replaced by a newline.
%O*	the same as %E*.
%p	is replaced by national representation of either “ante meridiem” (a.m.) or “post meridiem” (p.m.) as appropriate.
%R	is equivalent to “%H:%M”.
%r	is equivalent to “%I:%M:%S %p”.
%S	is replaced by the second as a decimal number (00-60).
%s	is replaced by the number of seconds since the Epoch, UTC (see mktime(3)).
%T	is equivalent to “%H:%M:%S”.
%t	is replaced by a tab.
%U	is replaced by the week number of the year (Sunday as the first day of the week) as a decimal number (00-53).
%u	is replaced by the weekday (Monday as the first day of the week) as a decimal number (1-7).
%V	is replaced by the week number of the year (Monday as the first day of the week) as a decimal number (01-53). If the week containing January 1 has four or more days in the new year, then it is week 1; otherwise it is the last week of the previous year, and the next week is week 1.
%v	is equivalent to “%e-%b-%Y”.
%W	is replaced by the week number of the year (Monday as the first day of the week) as a decimal number (00-53).
%w	is replaced by the weekday (Sunday as the first day of the week) as a decimal number (0-6).
%X	is replaced by national representation of the time.
%x	is replaced by national representation of the date.
%Y	is replaced by the year with century as a decimal number.
%y	is replaced by the year without century as a decimal number (00-99).
%Z	is replaced by the time zone name.
%z	is replaced by the time zone offset from UTC; a leading plus sign stands for east of UTC, a minus sign for west of UTC, hours and minutes follow with two digits each and no delimiter between them (common form for RFC 822 date headers).
%+	is replaced by national representation of the date and time (the format is similar to that produced by date(1)).
%-*	GNU libc extension. Do not do any padding when performing numerical outputs.
%_*	GNU libc extension. Explicitly specify space for padding.
%0*	GNU libc extension. Explicitly specify zero for padding.
%%	is replaced by %.

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