Look through gems and group by license

license.rb

# encoding: UTF-8

require 'securerandom'
require 'fileutils'

dir       = "tmp/#{SecureRandom.hex(4)}_gems"
gems      = `bundle exec gem list`.split
licenses  = {
  'Apache 2.0'  => [],
  'MIT'         => [],
  'Unknown'     => []
}

MIT = <<-LICENSE.strip.gsub(/\s+/, ' ').gsub(/[‘’\`'"]/, '')
  Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated
  documentation files (the "Software"), to deal in the Software without restriction, including without limitation the
  rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
  permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright
  notice and this permission notice shall be included in all copies or substantial portions of the Software. THE
  SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
  WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS
  OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
LICENSE

Dir.mkdir(dir)
Dir.chdir(dir) do
  gems.each_slice(2) do |name, version|
    version = version[1...-1]

    `gem unpack #{name} -v '=#{version}'`

    if path = Dir.glob("#{name}-#{version}/*LICENSE*").first
      license = File.basename(path)
      file    = File.read(path).strip.gsub(/\s+/, ' ').gsub(/[‘’\`'"]/, '')

      if license =~ /MIT-LICENSE/ || license =~ /LICENSE-MIT/ || file =~ /MIT License/ || file.include?(MIT)
        licenses['MIT'] << name
      elsif file =~ /http:\/\/www\.apache\.org\/licenses\/LICENSE-2\.0/ || file =~ /Apache License Version 2\.0/
        licenses['Apache 2.0'] << name
      else
        licenses['Unknown'] << name
        FileUtils.move path, "#{name}-#{license}"
      end
    end

    FileUtils.rm_r("#{name}-#{version}/")
  end
end

puts licenses

FileUtils.rm_r(dir) if licenses['Unknown'].empty?