Enhancement for gem env

[forthrin]

The following rewrite of show_environment suggests improvements of gem env output.

Feedback on further improvements or alternative angles appreciated.

Feature	Benefits
Outputs YAML (near already)	Can parse, pipe to yq for colors, etc.
Checks file presence	Helpful in bug reports
Replaces Dir.home with ~	Redaction / Privacy
Centralizes formatting	DRY

Example output

RubyGems Environment:
  Version:
    - 4.0.20
  Platforms:
    - ruby
    - arm64-darwin-25
  Configuration:
    update_sources: true
    verbose: true
    backtrace: true
    bulk_threshold: 1000
    gem: --no-document
  Sources:
    - https://rubygems.org/
  Dependencies:
    Ruby version: 4.0.7 (2026-09-15 patchlevel 0) [arm64-darwin25]
    Ruby executable: /opt/homebrew/opt/ruby/bin/ruby
    Git executable: /usr/bin/git
  Directories:
    Global install: /opt/homebrew/lib/ruby/gems/4.0.0
    # Global config: /opt/homebrew/Cellar/ruby/4.0.7/etc
    Executable: /opt/homebrew/lib/ruby/gems/4.0.0/bin
    # User install: ~/.local/share/gem/ruby/4.0.0
    Spec cache: ~/.cache/gem/specs
    # Credentials: ~/.local/share/gem/credentials
  Gem path:
    - /opt/homebrew/lib/ruby/gems/4.0.0
    # - ~/.local/share/gem/ruby/4.0.0
    - /opt/homebrew/Cellar/ruby/4.0.7/lib/ruby/gems/4.0.0
  Shell path:
    - /opt/homebrew/bin
    - /opt/homebrew/sbin
    - /opt/homebrew/opt/ruby/bin
    - /usr/bin
    - /bin
    - /usr/sbin
    - /sbin
    - /opt/homebrew/lib/ruby/gems/4.0.0/bin

Code

  def exist(value)
    case value
    when %r{^/}
      File.stat(value)
    end
    ''
  rescue Errno::ENOENT
    '# '
  end

  def tree(items)
    items.flat_map do |group, items|
      items.compact.map do |item|
        item = [item].flatten
        line = exist(item.last) + (item.one? ? '- ' : '') + item.join(': ')
        line.prepend('    ').gsub(Dir.home, '~')
      end.prepend(format('  %s:', group))
    end
  end

  def show_environment # :nodoc:
    config = {}
    Gem.configuration.each do |name, value|
      config[name] = name == 'gemcutter_key' ? value.gsub(/./, '*') : value
    end
    {
      'Version' => [Gem::VERSION],
      'Platforms' => Gem.platforms.map(&:to_s),
      'Configuration' => config,
      'Sources' => Gem.sources.to_a,
      'Dependencies' => {
        'Ruby version' => "#{RUBY_VERSION} (#{RUBY_RELEASE_DATE} patchlevel #{RUBY_PATCHLEVEL}) [#{RUBY_PLATFORM}]",
        'Ruby executable' => Gem.ruby,
        'Git executable' => git_path
      },
      'Directories' => {
        'Global install' => Gem.dir,
        'Global config' => Gem::ConfigFile::SYSTEM_CONFIG_PATH,
        'Executable' => Gem.bindir,
        'User install' => Gem.user_dir,
        'Prefix' => Gem.prefix,
        'Spec cache' => Gem.spec_cache_dir,
        'Credentials' => Gem.configuration.credentials_path
      },
      'Gem path' => ([Gem.dir] + Gem.path).uniq,
      'Shell path' => ENV['PATH'].split(File::PATH_SEPARATOR)
    }.then { tree(it).prepend('RubyGems Environment:').join("\n") }
  end

[hsbt]

I can accept this as an option, keeping the default output unchanged since tools such as Passenger 6.2.0 scrape labels like INSTALLATION DIRECTORY:. How about building the data as a Hash and printing it with --json or --yaml?

[forthrin]

Indeed it does. They will no doubt appreciate structured data once this is provided.

    `#{gem_command} env` =~ /INSTALLATION DIRECTORY: (.+)/

So need new options. Also the legacy "almost YAML" format should be deprecated after a while, having no benefits over actual YAML.

$ gem env --help
    -j, --json                       Output as JSON
    -y, --yaml                       Output as YAML

Question: Should order and hierarchy of legacy output be exactly preserved in JSON and YAML? (Example above adds groups for own directories, external dependencies, etc. for improved readability -- and parsability.)