I have not found a solution to the problem, however someone did already ask about the same problem a few days ago - (Rails Server Keeps Exiting (SocketError))
After I start a rails server the system returns some error I cannot understand. To install Ruby on Rails on my mac I did everything as listed on http://railsapps.github.io/installrubyonrails-mac.html
here is my terminal response:
$ rails server => Booting WEBrick => Rails 4.2.0 application starting in development on http://localhost:3000 => Run `rails server -h` for more startup options => Ctrl-C to shutdown server [2015-02-28 02:14:46] INFO WEBrick 1.3.1 [2015-02-28 02:14:46] INFO ruby 2.2.0 (2014-12-25) [x86_64-darwin14] Exiting /Users/alexshel/.rvm/rubies/ruby-2.2.0/lib/ruby/2.2.0/socket.rb:232:in `getaddrinfo': getaddrinfo: nodename nor servname provided, or not known (SocketError) from /Users/alexshel/.rvm/rubies/ruby-2.2.0/lib/ruby/2.2.0/socket.rb:232:in `foreach' from /Users/alexshel/.rvm/rubies/ruby-2.2.0/lib/ruby/2.2.0/socket.rb:459:in `tcp_server_sockets' from /Users/alexshel/.rvm/rubies/ruby-2.2.0/lib/ruby/2.2.0/webrick/utils.rb:70:in `create_listeners' from /Users/alexshel/.rvm/rubies/ruby-2.2.0/lib/ruby/2.2.0/webrick/server.rb:133:in `listen' from /Users/alexshel/.rvm/rubies/ruby-2.2.0/lib/ruby/2.2.0/webrick/server.rb:114:in `initialize' from /Users/alexshel/.rvm/rubies/ruby-2.2.0/lib/ruby/2.2.0/webrick/httpserver.rb:45:in `initialize' from /Users/alexshel/.rvm/gems/ruby-2.2.0@global/gems/rack-1.6.0/lib/rack/handler/webrick.rb:32:in `new' from /Users/alexshel/.rvm/gems/ruby-2.2.0@global/gems/rack-1.6.0/lib/rack/handler/webrick.rb:32:in `run' from /Users/alexshel/.rvm/gems/ruby-2.2.0@global/gems/rack-1.6.0/lib/rack/server.rb:286:in `start' from /Users/alexshel/.rvm/gems/ruby-2.2.0@global/gems/railties-4.2.0/lib/rails/commands/server.rb:80:in `start' from /Users/alexshel/.rvm/gems/ruby-2.2.0@global/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:80:in `block in server' from /Users/alexshel/.rvm/gems/ruby-2.2.0@global/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:75:in `tap' from /Users/alexshel/.rvm/gems/ruby-2.2.0@global/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:75:in `server' from /Users/alexshel/.rvm/gems/ruby-2.2.0@global/gems/railties-4.2.0/lib/rails/commands/commands_tasks.rb:39:in `run_command!' from /Users/alexshel/.rvm/gems/ruby-2.2.0@global/gems/railties-4.2.0/lib/rails/commands.rb:17:in `<top (required)>' from /Users/alexshel/workspace/myapp/bin/rails:8:in `require' from /Users/alexshel/workspace/myapp/bin/rails:8:in `<top (required)>' from /Users/alexshel/.rvm/gems/ruby-2.2.0@myapp/gems/spring-1.3.3/lib/spring/client/rails.rb:27:in `load' from /Users/alexshel/.rvm/gems/ruby-2.2.0@myapp/gems/spring-1.3.3/lib/spring/client/rails.rb:27:in `call' from /Users/alexshel/.rvm/gems/ruby-2.2.0@myapp/gems/spring-1.3.3/lib/spring/client/command.rb:7:in `call' from /Users/alexshel/.rvm/gems/ruby-2.2.0@myapp/gems/spring-1.3.3/lib/spring/client.rb:26:in `run' from /Users/alexshel/.rvm/gems/ruby-2.2.0@myapp/gems/spring-1.3.3/bin/spring:48:in `<top (required)>' from /Users/alexshel/.rvm/gems/ruby-2.2.0@myapp/gems/spring-1.3.3/lib/spring/binstub.rb:11:in `load' from /Users/alexshel/.rvm/gems/ruby-2.2.0@myapp/gems/spring-1.3.3/lib/spring/binstub.rb:11:in `<top (required)>' from /Users/alexshel/workspace/myapp/bin/spring:13:in `require' from /Users/alexshel/workspace/myapp/bin/spring:13:in `<top (required)>' from bin/rails:3:in `load' from bin/rails:3:in `<main>' Please help.