Ruby date and time formats

gistfile1.textile

Letter	Output	Example
%A	full day of week
%a	abbrev day of week
%B	full month name
%b	abbrev month name
%C	century (first two digits of year)
%c	Day, month, time. year	Thu Mar 17 11:20:10 2011
%D	western format with slashes	mm/dd/yy
%d	day of month (zero-padded)	02
%e	day of month (space-padded)	_2
%F	Year-month-day (with dash)	yyyy-mm-dd
%G	4-digit year
%g	2-digit year
%H	Hour (24 hour format)
%h	abbrev month
%I	hour (12 hour format)
%j	day of year (number of days since Jan 1)
%k	hour (24 hour format)
%l	hour (12 hour format space padded)
%M	minute
%m	month (zero padded)
%n	newline
%P	am or pm (lowercase)
%p	AM or PM (uppercase)
%Q	milli-seconds since unix epoch (Jan 1 1970)
%R	hour:minute	11:20
%r	hour:minute:second AM/PM	11:20:10 AM
%S	seconds
%s	seconds since unix epoch (Jan 1 1970)
%u	weekday as a decimal number
%U	week number of the current year as a decimal number, starting with the first Sunday as the first day of the first week	21
%V	The ISO 8601:1988 week number of the current year as a decimal number, range 01 to 53, where week 1 is the first week that has at least 4 days in the current year, and with Monday as the first day of the week.	22
%W	week number of the current year as a decimal number, starting with the first Monday as the first day of the first week	21
%w	day of the week as a decimal, Sunday being 0, Saturday being 6
%x	preferred date representation for the current locale without the time
%X	preferred time representation for the current locale without the date
%y	year as a decimal number without a century (range 00 to 99)
%Y	year as a decimal number including the century
%Z	time zone abbreviation	CET
%z	timezone offset to GMT	+0100
%%	literal `%’ character