Sometimes I want to do natural language datetime calculations from the commandline, just to work out things like "what date will it be in 60 days" or "when was 30 days ago". This helps.

strtotime.rb

#!/usr/bin/env ruby

# Requirements: Ruby and the Chronic gem
#
# Install Chronic with: `gem install chronic`
#
# Examples:
#
#   $ strtotime 'in 60 days'
#   6 Dec 2013 14:55:44
#
#   $ strtotime '30 days ago' '2013-01-01'
#   2 Dec 2013 12:00:00
#
# Installation (adjust paths as appropriate):
#
# 1. Download it
# 2. mv ~/Downloads/strtotime.rb ~/bin/strtotime
# 3. chmod +x ~/bin/strtotime

require 'chronic'

now = ARGV[1] ? Chronic.parse(ARGV[1]) : Time.now

time = Chronic.parse(ARGV[0], :now => now)
if time
  puts time.strftime('%-d %b %Y %H:%M:%S')
else
  $stderr.puts "Couldn't parse date"
  exit 1
end