Create a Time in a specific timezone in Ruby

ruby_timezone.rb

require 'time'

def format_time time_str
  old_tz = ENV['TZ']

  return if time_str.nil?

  ENV['TZ'] = 'America/New_York'
  Time.parse time_str
ensure
  ENV['TZ'] = old_tz
end

Time.parse 'Aug 04'
#=> 2014-08-04 00:00:00 -0700

format_time 'Aug 04'
#=> 2014-08-04 00:00:00 -0400

Time.parse 'Aug 04'
#=> 2014-08-04 00:00:00 -0700

ENV['TZ'] = 'Europe/Berlin'
#=> "Europe/Berlin"

Time.parse 'Aug 04'
#=> 2014-08-04 00:00:00 +0200

format_time 'Aug 04'
#=> 2014-08-04 00:00:00 -0400

Time.parse 'Aug 04'
#=> 2014-08-04 00:00:00 +0200