RubyGems 2.0 includes several new features and many breaking changes. Some of these changes will cause existing software to break. These changes are a result of improvements to the internals of RubyGems that make it more maintainable and improve APIs for RubyGems users.

If you are using bundler be sure to install a 1.3.0.prerelease version or newer. Older versions of bundler will not work with RubyGems 2.0.

Changes since RubyGems 1.8.25 (including past pre-releases):

Breaking changes:

• Deprecated Gem.unresolved_deps in favor of Gem::Specification.unresolved_deps
• Merged Gem::Builder into Gem::Package. Use Gem::Package.build(spec) instead of Gem::Builder.new(spec).build
• Merged Gem::Format into Gem::Package. Use Gem::Package.new instead of Gem::Format.from_file_by_path
• Moved Gem::OldFormat to Gem::Package::Old. Gem::Package will automatically detect old gems for you, so there is no need to refer to it.
• Removed Gem::DocManager, replaced by Gem::RDoc and done_installing hook
• Removed Gem::Package::TarInput in favor of Gem::Package
• Removed Gem::Package::TarOutput in favor of Gem::Package
• Removed Gem::RemoteFetcher#open_uri_or_path. (steveklabnik)
• Removed Gem::SSL in favor of using OpenSSL directly
• Removed Gem.loaded_path
• Removed RSS generation from the gem indexer
• Removed benchmark option from .gemrc
• Removed broken YAML gemspec support in gem build
• Removed support for Ruby 1.9.1
• Removed many deprecated methods

Major enhancements:

• Improved support for default gems shipping with ruby 2.0.0+
• A gem can have arbitrary metadata through Gem::Specification#metadata
• gem search now defaults to –remote and is anchored like gem list. Fixes #166
• Added –document to replace –rdoc and –ri. Use –no-document to disable documentation, –document=rdoc to only generate rdoc.
• Only ri-format documentation is generated by default.
• gem server uses RDoc::Servlet from RDoc 4.0 to generate HTML documentation.
• Add ability to install gems directly from a compatible gemdep file (Gemfile, Isolate, gem.deps.rb) gem install --file path
• Add ability to load gem activation information from a gemdeps file (Gemfile, Isolate, gem.deps.rb). Set RUBYGEMS_GEMDEPS=path to have it loaded. Use - as the path to autodetect (current and parent directories are searched).

Minor enhancements:

• Added gem check --doctor to clean up after failed uninstallation. Bug #419 by Erik Hollensbe
• RubyGems no longer defaults to uninstalling gems if a dependency would be broken. Now you must manually say “yes”. Pull Request #406 by Shannon Skipper.
• Gem::DependencyInstaller now passes build_args down to the installer. Pull Request #412 by Sam Rawlins.
• Added a cmake builder. Pull request #265 by Allan Espinosa.
• Removed rubyforge page from gem list output
• Added –only-executables option to gem pristine. Fixes #326
• Added -I flag for ‘gem query’ to exclude installed items
• Added Gem.install(name, version=default) for interactive sessions
• Added Gem::FilePermissionError#directory
• Added Gem::rubygems_version which is like Gem::ruby_version
• Added RUBYGEMS_HOST documentation to gem env
• Added a post_installs hook that runs after Gem::DependencyInstaller finishes installing a set of gems
• Added a usage method for Gem::Commands::OwnerCommand. (ffmike)
• Added an optional type parameter to Gem::Specification#doc_dir.
• Added announcements url and clarified how to file tickets
• Added guidance for how to use rdoc and ri in setup command. (jjb)
• Attempting to install multiple gems with –version is now an error. You can specify per-gem versions like rake:0.9.5
• Clarified Gem::CommandManager example code to avoid multi load problems. (baroquebobcat)
• Corrupt or bad cached specs are now re-downloaded. (cookrn)
• Extension build arguments are saved from install and reused for pristine
• If the OS allows it, documentation is built in a forked background process. (alexch)
• Imported gem yank from the gemcutter gem. Fixes #177, #343
• Packaged gems now contain and verify SHA1 checksums
• Removed commas from gem update summary so you can paste it back to cleanup. (amatsuda)
• RubyGems will now warn when building gems with prerelease dependencies. Fixes #255
• The RUBYGEMS_HOST environment variable is used to determine appropriate API key for pushing or yanking gems
• Uninstall is now performed in reverse topological order.
• Users are told what to type when they try to uninstall a gem outside GEM_HOME
• When building gems with non-world-readable files a warning is shown.

Bug fixes:

• Gem.refresh now maintains the active gem list. Clearing the list would cause double-loads which would cause other bugs. Pull Request #427 by Jeremy Evans
• RubyGems now refuses to read the gem push credentials file if it has insecure permissions. Pull Request #438 by Shannon Skipper
• RubyGems now requires a local gem name to end in ‘.gem’. Issue #407 by Santiago Pastorino.
• Do not allow old-format gems to be installed with a security policy that verifies data.
• Gem installation will fail if RubyGems cannot load the specification from the gem. Bug #419 by Erik Hollensbe
• RubyGems tests now run in FIPS mode. Issue #365 by Vít Ondruch
• Only update the spec cache when we have permission. Ruby Bug #7509
• gem install now ignores directories and non .gem files that match the gem to install. Bug #407 by Santiago Pastorino.
• Added PID to setup bin_file while installing RubyGems to protect against errors. Fixes #328 by ConradIrwin
• Added missing require in Gem::Uninstaller when format_executable is set. (sakuro)
• Exact gem command name matches are now chosen even if a longer command overlaps the exact name
• Fixed Gem.loaded_path? with a Pathname instance. (mattetti)
• Fixed Gem::Dependency.new mismatch with rubygems.org checks
• Fixed SecurityError in Gem::Specification.load when $SAFE=1. (ged)
• Fixed SystemStackError with “gem list -r -a” on 1.9 (cldwalker)
• Fixed gem owners command so that exceptions don’t stop the rest of the command from completing
• Fixed gem unpack uninstalled_gem default version picker.
• Fixed defunct rubyforge urls in gem command line help
• Fixed documentation for the various hooks collections
• Fixed documentation generation on setup when the gem directory does not exist. Fixes #253
• Fixed documentation to reflect where defaults overrides are loaded from. (ferrous26)
• Fixed editing of a Makefile with 8-bit characters. Fixes #181
• Fixed gem loading issue caused by dependencies not resolving.
• Fixed independent testing of test_gem_package_tar_output. Ruby Bug #4686 by Shota Fukumori
• Fixed typo in uninstall message. (sandal)
• Gem::Requirement#<=> returns nil on non-requirement arg.
• Gem::Requirement.satisfied_by? raises ArgumentError if given a non-version argument
• Gem::Version#initialize no longer modifies its parameter. (miaout17)
• Group-writable permissions are now allowed for gem repositories. (ctcherry)
• Memoized values in Gem::Specification are now reset the version or platform changes. Fixes #78
• More specific errors are raised for bad requirements. (arsduo)
• Removed reference to ‘sources’ gem in documentation
• Removed unused block arguments to avoid creating Proc objects. (k-tsj)
• RubyGems now asks before overwriting executable wrappers. Ruby Bug #1800
• The bindir is now created with mkdir_p during install. (voxik)
• URI scheme matching is no longer case-sensitive. Fixes #322
• ext/builder now checks $MAKE as well as $make (okkez)

Changes since RubyGems 2.0.0.rc.2:

Bug fixes: * Gem.gzip and Gem.gunzip now return strings with BINARY encoding. Issue #450 by Jeremy Kemper * Fixed placement of executables with –user-install. Ruby bug #7779 by Jon Forums. * Fixed gem update with –user-install. Ruby bug #7779 by Jon Forums. * Fixed test_initialize_user_install for windows. Ruby bug #7885 by Luis Lavena. * Create extension destination directory before building extensions. Ruby Bug #7897 and patch by Kenta Murata. * Fixed verification of gems at LowSecurity due to missing signature. Thanks to André Arko.