我刚刚把系统升级到了El Capitan，但是当我启动rails服务器时（在Yosemite上完全正常），出现了以下警告。
Ignoring bcrypt-3.1.10 because its extensions are not built. Try: gem pristine bcrypt --version 3.1.10
Ignoring bcrypt-ruby-3.1.2 because its extensions are not built. Try: gem pristine bcrypt-ruby --version 3.1.2
Ignoring bcrypt-ruby-3.0.1 because its extensions are not built. Try: gem pristine bcrypt-ruby --version 3.0.1
Ignoring binding_of_caller-0.7.2 because its extensions are not built. Try: gem pristine binding_of_caller --version 0.7.2
Warning: Running `gem pristine --all` to regenerate your installed gemspecs (and deleting then reinstalling your bundle if you use bundle --path) will improve the startup performance of Spring.
当运行引用命令时，我会得到以下内容：
-bash: bundle: command not found
rails update
Ignoring json-1.8.1 because its extensions are not built. Try: gem pristine json --version 1.8.1
Ignoring json-1.8.2 because its extensions are not built. Try: gem pristine json --version 1.8.2
Ignoring json-1.8.3 because its extensions are not built. Try: gem pristine json --version 1.8.3
Ignoring nokogiri-1.6.6.2 because its extensions are not built. Try: gem pristine nokogiri --version 1.6.6.2
Ignoring atomic-1.1.14 because its extensions are not built. Try: gem pristine atomic --version 1.1.14
Ignoring atomic-1.1.14 because its extensions are not built. Try: gem pristine atomic --version 1.1.14
Ignoring bcrypt-ruby-3.0.1 because its extensions are not built. Try: gem pristine bcrypt-ruby --version 3.0.1
Ignoring binding_of_caller-0.7.2 because its extensions are not built. Try: gem pristine binding_of_caller --version 0.7.2
Warning: Running `gem pristine --all` to regenerate your installed gemspecs (and deleting then reinstalling your bundle if you use bundle --path) will improve the startup performance of Spring.
Could not find bcrypt-3.1.10 in any of the sources
Run `bundle install` to install missing gems.
我也尝试运行了以下命令：
sudo gem pristine --all
Restoring gems to pristine condition...
ERROR: While executing gem ... (Errno::EPERM)
Operation not permitted - /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/gems/2.0.0/gems/CFPropertyList-2.2.8/README
现在，它甚至找不到bundle安装路径。看起来更新真的把它搞砸了。
当我运行gem pristine --all时，我得到以下结果：
Restored bcrypt-ruby-3.1.5
Skipped bigdecimal-1.2.0, it is a default gem
Building native extensions. This could take a while...
Restored binding_of_caller-0.7.2
Restored bootstrap-sass-3.3.5.1
Restored builder-3.2.2
Restored builder-3.1.4
Restored bundler-1.10.6
Restored bundler-1.9.6
Building native extensions. This could take a while...
ERROR: While executing gem ... (Gem::Ext::BuildError)
ERROR: Failed to build gem native extension.
/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby -r ./siteconf20151001-3494-1jca623.rb extconf.rb
creating Makefile
make "DESTDIR=" clean
make "DESTDIR="
make: *** No rule to make target `/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.10.sdk/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/include/ruby-2.0.0/universal-darwin15/ruby/config.h', needed by `breakpoint.o'. Stop.
make failed, exit code 2
Gem files will remain installed in /Library/Ruby/Gems/2.0.0/gems/byebug-6.0.2 for inspection.
Results logged to /Library/Ruby/Gems/2.0.0/extensions/universal-darwin-15/2.0.0/byebug-6.0.2/gem_make.out