Ruby/Time/Time format

t = Time.local(2006, 1, 1)
t.strftime("%A %A %A!")                     # => "Sunday Sunday Sunday!"
t.strftime("%a %a %a!")                     # => "Sun Sun Sun!"

last_modified = "Tue, 05 Sep 2006 16:05:51 GMT"
puts Time.httpdate(last_modified)

timestamp = "2001-04-17T19:23:17.201Z"
puts t = Time.iso8601(timestamp)    # => Tue Apr 17 19:23:17 UTC 2001
puts t.sec                          # => 17
puts t.tv_usec                      # => 201000

require "time"
mail_received = "Tue, 1 Jul 2003 10:52:37 +0200"
puts Time.rfc822(mail_received)

Directive   Description
%a          Abbreviated weekday name (Sun)
%A          Full weekday name (Sunday)
%b          Abbreviated month name (Jan)
%B          Full month name (January)
%c          Preferred local date and time representation
%d          Day of the month (01 to 31)
%H          Hour of the day, 24-hour clock (00 to 23)
%I          Hour of the day, 12-hour clock (01 to 12)
%j          Day of the year (001 to 366)
%m          Month of the year (01 to 12)
%M          Minute of the hour (00 to 59)
%p          Meridian indicator (AM or PM)
%S          Second of the minute (00 to 60)
%U          Week number of the current year, starting with the first Sunday as the first day of the first week (00 to 53)
%W          Week number of the current year, starting with the first Monday as the first day of the first week (00 to 53)
%w          Day of the week (0 to 6; Sunday is 0)
%x          Preferred representation for the date alone, no time
%X          Preferred representation for the time alone, no date
%y          Year without a century (00 to 99)
%Y          Year with a century
%Z          Time zone name
%%          Literal % character