unpack

#!/usr/bin/ruby

archive_types = { 
  "tar"     => ["tar", "-xvf"],
  "tar.gz"  => ["tar", "-zxvf"],
  "tgz"     => ["tar", "-zxvf"],
  "tar.bz2" => ["tar", "-jxvf"],
  "rar"     => ["unrar", "x"],
  "zip"     => ["unzip"]
}

ARGV.each do |target|
  file_type = target.match(/\.([^\W0-9]{3}?(\.\w+)?)$/)[1]
  if archive_types[file_type]
    args = archive_types[file_type].push target
    system(*args)
  else
    puts "Dunno how to deal with '#{file_type}' files"
  end
end