Ruby script helps me convert paperclip handled file to 48x48 size, running under the avatars root directory.

conver_48.rb

#!/usr/bin/env ruby
require 'fileutils'

def ignored_dir(name)
  if name == '.' or name == '..'
    return true
  else
    return false
  end
end

Dir.foreach('.') do |d|
  next if ignored_dir(d)
  if File.directory? d
    medium_dir = "#{d}/medium"
    if !File.exists? medium_dir
      FileUtils.mkdir medium_dir
    end

    original_dir = "#{d}/original"
    Dir.foreach(original_dir) do |s|
      next if ignored_dir(s) 
      `convert #{original_dir}/#{s} -resize 48x48 #{medium_dir}/#{s}`
      puts "convert #{original_dir}/#{s} -resize 48x48 #{medium_dir}/#{s}"
    end
  end
end