Question

I’m trying to check if a file (on web) was modified since the last time I checked. Is it possible to do this by getting http headers to read the last time the file was modified (or uploaded)?

Answer 1

You can use the built-in Net::HTTP library to do most of this for you:

require 'net/http'

Net::HTTP.start('stackoverflow.com') do |http|
  response = http.request_head('/robots.txt')

  response['Last-Modified']
  # => Sat, 04 Jun 2011 08:51:44 GMT
end

If you want, you can convert that to a proper date using Time.parse.