rmultirename.rb

#!/usr/bin/ruby

if ((ARGV[0] == nil) || (ARGV[0] == '--help'))
  puts "Usage: rmultirename [PATTERN] [REPLACEMENT]"
  printf "Example: rmultirename htm html \n\n"
  exit
end

STDOUT.sync = true

IO.popen(%&ls ./&) do |f|
  @massive = Array.new
  until f.eof?
    @massive.push f.gets
  end
end

@massive.each {|elm| system "mv #{elm.chomp} #{elm.gsub(ARGV[0],ARGV[1])}" if elm.include? ARGV[0] }