# File lib/rubygems/commands/sources_command.rb, line 38
  def execute
    options[:list] = !(options[:add] || options[:remove] || options[:clear_all] || options[:update])

    if options[:clear_all] then
      remove_cache_file("user", Gem::SourceInfoCache.user_cache_file)
      remove_cache_file("system", Gem::SourceInfoCache.system_cache_file)
    end

    if options[:add] then
      source_uri = options[:add]

      sice = Gem::SourceInfoCacheEntry.new nil, nil
      begin
        sice.refresh source_uri

        Gem::SourceInfoCache.cache_data[source_uri] = sice
        Gem::SourceInfoCache.cache.update
        Gem::SourceInfoCache.cache.flush

        Gem.sources << source_uri
        Gem.configuration.write

        say "#{source_uri} added to sources"
      rescue URI::Error, ArgumentError
        say "#{source_uri} is not a URI"
      rescue Gem::RemoteFetcher::FetchError => e
        say "Error fetching #{source_uri}:\n\t#{e.message}"
      end
    end

    if options[:update] then
      Gem::SourceInfoCache.cache.refresh
      Gem::SourceInfoCache.cache.flush

      say "source cache successfully updated"
    end

    if options[:remove] then
      source_uri = options[:remove]

      unless Gem.sources.include? source_uri then
        say "source #{source_uri} not present in cache"
      else
        Gem::SourceInfoCache.cache_data.delete source_uri
        Gem::SourceInfoCache.cache.update
        Gem::SourceInfoCache.cache.flush
        Gem.sources.delete source_uri
        Gem.configuration.write

        say "#{source_uri} removed from sources"
      end
    end

    if options[:list] then
      say "*** CURRENT SOURCES ***"
      say

      Gem.sources.each do |source_uri|
        say source_uri
      end
    end
  end