Overcommit plugin for checking the license header (simpler than upstream)

.overcommit.yml

PreCommit:
  UpdatedLicenseHeader:
    enabled: true
    description: 'Checking if license is present and updated'

updated_license_header.rb

module Overcommit::Hook::PreCommit
  class UpdatedLicenseHeader < Base
    def run
      errors = []

      applicable_files.each do |file|
        if header_of_file(file) !~ /Copyright .*#{Time.now.year}/ # rubocop:disable Rails/TimeZone
          errors << "#{file} needs an updated license header"
        end
      end

      return :fail, errors.join("\n") if errors.any?

      :pass
    end

    private

    def header_of_file(fn)
      `head -n 5 --silent #{fn}`
    end
  end
end