photo_renamer.rb

#!/usr/bin/env ruby
#
# reads filenames from stdin and renames them according to contained
# exif data
#

require 'time'
require 'yaml'
require 'fileutils'

filenames = ARGF.read.strip.split("\n") || []

renames = []

filenames.each do |full|
  
  dirname = File.dirname full
  begin
    create_date = Time.strptime(`exiftool -createDate "#{full}"`[34..255].strip, "%Y:%m:%d %H:%M:%S")
  rescue
    begin
      # try to use modifydate ....
      create_date = Time.strptime(`exiftool -modifyDate "#{full}"`[34..255].strip, "%Y:%m:%d %H:%M:%S")
    rescue 
      # try to use trackCreateDate
      create_date = Time.strptime(`exiftool -trackCreateDate "#{full}"`[34..255].strip, "%Y:%m:%d %H:%M:%S")
    end
  end
  
  extension = full.split('.').last

  newfile = create_date.strftime("%Y-%m-%d-%H%M%S") + "_" + `sha224sum "#{full}"`[0..5].strip + "." + extension

  renames << [full, File.join(dirname, newfile)] if full != File.join(dirname, newfile)
end

renames.each do |from, to|
  puts "rename '#{from}' to '#{to}'"
  FileUtils.mv(from, to)
end