Rails-tutorial Chapter 1: rails server isn't working on Cloud9

Question

https://www.railstutorial.org/book/beginning#sec-rails_server

I have reached this step, and I'm using the cloud9 environment. When I run the server as per Listing 1.7 on that tutorial, however, I get this error:

myname@rails-tutorial:~/workspace/hello_app $ rails server -p $PORT -b $IP
=> Booting WEBrick
=> Rails 4.2.0.beta2 application starting in development on http://0.0.0.0:8080
=> Run `rails server -h` for more startup options
=> Ctrl-C to shutdown server
[2014-10-30 21:44:22] INFO  WEBrick 1.3.1
[2014-10-30 21:44:22] INFO  ruby 2.1.1 (2014-02-24) [x86_64-linux]
Exiting /usr/local/rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/socket.rb:206:in `bind': Address already in use - bind(2) for 0.0.0.0:8080 (Errno::EADDRINUSE)
    from /usr/local/rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/socket.rb:206:in `listen'
    from /usr/local/rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/socket.rb:461:in `block in tcp_server_sockets'
    from /usr/local/rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/socket.rb:232:in `each'
    from /usr/local/rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/socket.rb:232:in `foreach'
    from /usr/local/rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/socket.rb:459:in `tcp_server_sockets'
    from /usr/local/rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/webrick/utils.rb:75:in `create_listeners'
    from /usr/local/rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/webrick/server.rb:132:in `listen'
    from /usr/local/rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/webrick/server.rb:113:in `initialize'
    from /usr/local/rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/webrick/httpserver.rb:45:in `initialize'
    from /usr/local/rvm/gems/ruby-2.1.1@rails4/gems/rack-1.6.0.beta/lib/rack/handler/webrick.rb:32:in `new'
    from /usr/local/rvm/gems/ruby-2.1.1@rails4/gems/rack-1.6.0.beta/lib/rack/handler/webrick.rb:32:in `run'
    from /usr/local/rvm/gems/ruby-2.1.1@rails4/gems/rack-1.6.0.beta/lib/rack/server.rb:288:in `start'
    from /usr/local/rvm/gems/ruby-2.1.1@rails4/gems/railties-4.2.0.beta2/lib/rails/commands/server.rb:80:in `start'
    from /usr/local/rvm/gems/ruby-2.1.1@rails4/gems/railties-4.2.0.beta2/lib/rails/commands/commands_tasks.rb:80:in `block in server'
    from /usr/local/rvm/gems/ruby-2.1.1@rails4/gems/railties-4.2.0.beta2/lib/rails/commands/commands_tasks.rb:75:in `tap'
    from /usr/local/rvm/gems/ruby-2.1.1@rails4/gems/railties-4.2.0.beta2/lib/rails/commands/commands_tasks.rb:75:in `server'
    from /usr/local/rvm/gems/ruby-2.1.1@rails4/gems/railties-4.2.0.beta2/lib/rails/commands/commands_tasks.rb:39:in `run_command!'
    from /usr/local/rvm/gems/ruby-2.1.1@rails4/gems/railties-4.2.0.beta2/lib/rails/commands.rb:17:in `<top (required)>'
    from /home/ubuntu/workspace/hello_app/bin/rails:8:in `require'
    from /home/ubuntu/workspace/hello_app/bin/rails:8:in `<top (required)>'
    from /usr/local/rvm/gems/ruby-2.1.1@rails4/gems/spring-1.1.3/lib/spring/client/rails.rb:27:in `load'
    from /usr/local/rvm/gems/ruby-2.1.1@rails4/gems/spring-1.1.3/lib/spring/client/rails.rb:27:in `call'
    from /usr/local/rvm/gems/ruby-2.1.1@rails4/gems/spring-1.1.3/lib/spring/client/command.rb:7:in `call'
    from /usr/local/rvm/gems/ruby-2.1.1@rails4/gems/spring-1.1.3/lib/spring/client.rb:26:in `run'
    from /usr/local/rvm/gems/ruby-2.1.1@rails4/gems/spring-1.1.3/bin/spring:48:in `<top (required)>'
    from /usr/local/rvm/gems/ruby-2.1.1@rails4/gems/spring-1.1.3/lib/spring/binstub.rb:11:in `load'
    from /usr/local/rvm/gems/ruby-2.1.1@rails4/gems/spring-1.1.3/lib/spring/binstub.rb:11:in `<top (required)>'
    from /home/ubuntu/workspace/hello_app/bin/spring:16:in `require'
    from /home/ubuntu/workspace/hello_app/bin/spring:16:in `<top (required)>'
    from bin/rails:3:in `load'
    from bin/rails:3:in `<main>'

I've tried specifying a different port, but that doesn't work and the cloud9 environment suggests to me I should just use the $PORT variable.

The error "Address already in use - bind(2) for 0.0.0.0:8080 (Errno::EADDRINUSE)" implies that I already have a rails server running, but I don't. I'm not really sure what to do here and the tutorial doesn't suggest any method of troubleshooting this issue.

Answer 1

I learned that you can use the command killall ruby to stop any of the ruby processes which helped me because I had mistakenly run the rails server -b $IP -p $PORT command at the ~/workspace level in the tutorial. I found the answer in can't open rails server