Gem::Commands::SetupCommand#execute

# File tmp/rubies/ruby-4.0.0/lib/rubygems/commands/setup_command.rb, line 139
def execute
  @verbose = Gem.configuration.really_verbose

  require "fileutils"
  if Gem.configuration.really_verbose
    extend FileUtils::Verbose
  else
    extend FileUtils
  end
  extend MakeDirs

  lib_dir, bin_dir = make_destination_dirs
  man_dir = generate_default_man_dir

  install_lib lib_dir

  install_executables bin_dir

  remove_old_bin_files bin_dir

  remove_old_lib_files lib_dir

  # Can be removed one we drop support for bundler 2.2.3 (the last version installing man files to man_dir)
  remove_old_man_files man_dir if man_dir && File.exist?(man_dir)

  install_default_bundler_gem bin_dir

  if mode = options[:dir_mode]
    @mkdirs.uniq!
    File.chmod(mode, @mkdirs)
  end

  say "RubyGems #{Gem::VERSION} installed"

  regenerate_binstubs(bin_dir) if options[:regenerate_binstubs]
  regenerate_plugins(bin_dir) if options[:regenerate_plugins]

  uninstall_old_gemcutter

  documentation_success = install_rdoc

  say
  if @verbose
    say "-" * 78
    say
  end

  if options[:previous_version].empty?
    options[:previous_version] = Gem::VERSION.sub(/[0-9]+$/, "0")
  end

  options[:previous_version] = Gem::Version.new(options[:previous_version])

  show_release_notes

  say
  say "-" * 78
  say

  say "RubyGems installed the following executables:"
  say bin_file_names.map {|name| "\t#{name}\n" }
  say

  unless bin_file_names.grep(/#{File::SEPARATOR}gem$/)
    say "If `gem` was installed by a previous RubyGems installation, you may need"
    say "to remove it by hand."
    say
  end

  if documentation_success
    if options[:document].include? "rdoc"
      say "Rdoc documentation was installed. You may now invoke:"
      say "  gem server"
      say "and then peruse beautifully formatted documentation for your gems"
      say "with your web browser."
      say "If you do not wish to install this documentation in the future, use the"
      say "--no-document flag, or set it as the default in your ~/.gemrc file. See"
      say "'gem help env' for details."
      say
    end

    if options[:document].include? "ri"
      say "Ruby Interactive (ri) documentation was installed. ri is kind of like man "
      say "pages for Ruby libraries. You may access it like this:"
      say "  ri Classname"
      say "  ri Classname.class_method"
      say "  ri Classname#instance_method"
      say "If you do not wish to install this documentation in the future, use the"
      say "--no-document flag, or set it as the default in your ~/.gemrc file. See"
      say "'gem help env' for details."
      say
    end
  end
end