Script for mass renaming of files via Regexp

mass_rename.rb

#!/usr/bin/env ruby

require 'fileutils'

if ARGV.size < 3
  puts <<-USAGE
mass_rename [file1 file2 ...] <regexp> <replacement>
  USAGE
end

file_names, regexp, replacement = ARGV[0...-2], ARGV[-2], ARGV[-1]

file_names.each do |old_name|
  new_name = old_name.gsub(/#{regexp}/, replacement)
  if old_name != new_name
    puts "Renaming \"#{old_name}\"\tto  \"#{new_name}\"..."
    FileUtils.mv(old_name, new_name)
  end
end