rails で rails s をしたときName or service not known (SocketError) というエラーがでました

Question

`initialize': getaddrinfo: Name or service not known (SocketError)

全体はこんな感じです

 $ rails s -b $ip -p $PORt
=> Booting Puma
=> Rails 5.0.2 application starting in development on http://-p:8080
=> Run `rails server -h` for more startup options
Puma starting in single mode...
* Version 3.7.1 (ruby 2.3.0-p0), codename: Snowy Sagebrush
* Min threads: 5, max threads: 5
* Environment: development
* Listening on tcp://-p:8080
Exiting
/usr/local/rvm/gems/ruby-2.3.0/gems/puma-3.7.1/lib/puma/binder.rb:269:in `initialize': getaddrinfo: Name or service not known (SocketError)
        from /usr/local/rvm/gems/ruby-2.3.0/gems/puma-3.7.1/lib/puma/binder.rb:269:in `new'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/puma-3.7.1/lib/puma/binder.rb:269:in `add_tcp_listener'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/puma-3.7.1/lib/puma/binder.rb:105:in `block in parse'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/puma-3.7.1/lib/puma/binder.rb:88:in `each'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/puma-3.7.1/lib/puma/binder.rb:88:in `parse'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/puma-3.7.1/lib/puma/runner.rb:144:in `load_and_bind'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/puma-3.7.1/lib/puma/single.rb:87:in `run'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/puma-3.7.1/lib/puma/launcher.rb:171:in `run'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/puma-3.7.1/lib/rack/handler/puma.rb:58:in `run'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/rack-2.0.1/lib/rack/server.rb:296:in `start'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/railties-5.0.2/lib/rails/commands/server.rb:79:in `start'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/railties-5.0.2/lib/rails/commands/commands_tasks.rb:90:in `block in server'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/railties-5.0.2/lib/rails/commands/commands_tasks.rb:85:in `tap'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/railties-5.0.2/lib/rails/commands/commands_tasks.rb:85:in `server'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/railties-5.0.2/lib/rails/commands/commands_tasks.rb:49:in `run_command!'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/railties-5.0.2/lib/rails/commands.rb:18:in `<top (required)>'
        from /home/ubuntu/workspace/NewsPicks/bin/rails:9:in `require'
        from /home/ubuntu/workspace/NewsPicks/bin/rails:9:in `<top (required)>'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/spring-2.0.1/lib/spring/client/rails.rb:28:in `load'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/spring-2.0.1/lib/spring/client/rails.rb:28:in `call'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/spring-2.0.1/lib/spring/client/command.rb:7:in `call'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/spring-2.0.1/lib/spring/client.rb:30:in `run'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/spring-2.0.1/bin/spring:49:in `<top (required)>'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/spring-2.0.1/lib/spring/binstub.rb:31:in `load'
        from /usr/local/rvm/gems/ruby-2.3.0/gems/spring-2.0.1/lib/spring/binstub.rb:31:in `<top (required)>'
        from /home/ubuntu/workspace/NewsPicks/bin/spring:15:in `require'
        from /home/ubuntu/workspace/NewsPicks/bin/spring:15:in `<top (required)>'
        from bin/rails:3:in `load'
        from bin/rails:3:in `<main>'

思い当たるコードがないのでどれを載せたらいいのかもわかりません。念のため routes のコードを載せます。

Rails.application.routes.draw do
  
  devise_for :users
  root 'static_pages#home'
  get  '/help',    to: 'static_pages#help'
  get  '/about',   to: 'static_pages#about'
  get  '/signup',  to: 'users#new'
  
  # For details on the DSL available within this file, see http://guides.rubyonrails.org/routing.html
end

Answer 1

$ipと$PORtではなくて正しくは$IPと$PORTではないでしょうか。
大文字と小文字が区別されているために、正しく変数が展開されていないことが原因かとおもいます。。