After running the rails g controller command I get this is my error:
Could not find rake-12.2.1 in any of the sources (Bundler::GemNotFound)
/usr/lib/ruby/vendor_ruby/bundler/spec_set.rb:87:in
block in materialize': Could not find rake-12.2.1 in any of the sources (Bundler::GemNotFound) from /usr/lib/ruby/vendor_ruby/bundler/spec_set.rb:81:inmap!' from /usr/lib/ruby/vendor_ruby/bundler/spec_set.rb:81:inmaterialize' from /usr/lib/ruby/vendor_ruby/bundler/definition.rb:159:inspecs' from /usr/lib/ruby/vendor_ruby/bundler/definition.rb:218:inspecs_for' from /usr/lib/ruby/vendor_ruby/bundler/definition.rb:207:inrequested_specs' from /usr/lib/ruby/vendor_ruby/bundler/runtime.rb:109:inblock in definition_method' from /usr/lib/ruby/vendor_ruby/bundler/runtime.rb:21:insetup' from /usr/lib/ruby/vendor_ruby/bundler.rb:101:insetup' from /usr/lib/ruby/vendor_ruby/bundler/setup.rb:20:in' from /usr/local/lib/site_ruby/1.9.1/rubygems/core_ext/kernel_require.rb:55:inrequire' from /usr/local/lib/site_ruby/1.9.1/rubygems/core_ext/kernel_require.rb:55:inrequire' from /root/Desktop/blog/vendor/bundle/ruby/2.3.0/gems/spring-2.0.2/lib/spring/commands.rb:33:in<module:Spring>' from /root/Desktop/blog/vendor/bundle/ruby/2.3.0/gems/spring-2.0.2/lib/spring/commands.rb:4:in' from /usr/local/lib/site_ruby/1.9.1/rubygems/core_ext/kernel_require.rb:55:inrequire' from /usr/local/lib/site_ruby/1.9.1/rubygems/core_ext/kernel_require.rb:55:inrequire' from /root/Desktop/blog/vendor/bundle/ruby/2.3.0/gems/spring-2.0.2/lib/spring/server.rb:9:in<top (required)>' from /usr/local/lib/site_ruby/1.9.1/rubygems/core_ext/kernel_require.rb:55:inrequire' from /usr/local/lib/site_ruby/1.9.1/rubygems/core_ext/kernel_require.rb:55:inrequire' from /root/Desktop/blog/vendor/bundle/ruby/2.3.0/gems/spring-2.0.2/lib/spring/client/server.rb:9:incall' from /root/Desktop/blog/vendor/bundle/ruby/2.3.0/gems/spring-2.0.2/lib/spring/client/command.rb:7:incall' from /root/Desktop/blog/vendor/bundle/ruby/2.3.0/gems/spring-2.0.2/lib/spring/client.rb:30:inrun' from /root/Desktop/blog/vendor/bundle/ruby/2.3.0/gems/spring-2.0.2/bin/spring:49:in `'
bundle install? Try running it withbundle exec. - Marek Lipka