ROR for linux , I got a problem when creating a server

how do I fix this problem ?

andika@andika-HP:~/andikanug$ rails s
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.
/var/lib/gems/2.1.0/gems/execjs-2.5.2/lib/execjs/runtimes.rb:48:in
`autodetect': Could not find a JavaScript runtime. See
https://github.com/rails/execjs for a list of available runtimes.
(ExecJS::RuntimeUnavailable)
  from /var/lib/gems/2.1.0/gems/execjs-2.5.2/lib/execjs.rb:5:in
`<module:ExecJS>'
  from /var/lib/gems/2.1.0/gems/execjs-2.5.2/lib/execjs.rb:4:in `<top
(required)>'
  from /var/lib/gems/2.1.0/gems/uglifier-2.7.1/lib/uglifier.rb:3:in
`require'
  from /var/lib/gems/2.1.0/gems/uglifier-2.7.1/lib/uglifier.rb:3:in
`<top (required)>'
  from
/var/lib/gems/2.1.0/gems/bundler-1.9.4/lib/bundler/runtime.rb:76:in
`require'
  from
/var/lib/gems/2.1.0/gems/bundler-1.9.4/lib/bundler/runtime.rb:76:in
`block (2 levels) in require'
  from
/var/lib/gems/2.1.0/gems/bundler-1.9.4/lib/bundler/runtime.rb:72:in
`each'
  from
/var/lib/gems/2.1.0/gems/bundler-1.9.4/lib/bundler/runtime.rb:72:in
`block in require'
  from
/var/lib/gems/2.1.0/gems/bundler-1.9.4/lib/bundler/runtime.rb:61:in
`each'
  from
/var/lib/gems/2.1.0/gems/bundler-1.9.4/lib/bundler/runtime.rb:61:in
`require'
  from /var/lib/gems/2.1.0/gems/bundler-1.9.4/lib/bundler.rb:134:in
`require'
  from /home/andika/andikanug/config/application.rb:7:in `<top
(required)>'
  from
/var/lib/gems/2.1.0/gems/railties-4.2.1/lib/rails/commands/commands_tasks.rb:78:in
`require'
  from
/var/lib/gems/2.1.0/gems/railties-4.2.1/lib/rails/commands/commands_tasks.rb:78:in
`block in server'
  from
/var/lib/gems/2.1.0/gems/railties-4.2.1/lib/rails/commands/commands_tasks.rb:75:in
`tap'
  from
/var/lib/gems/2.1.0/gems/railties-4.2.1/lib/rails/commands/commands_tasks.rb:75:in
`server'
  from
/var/lib/gems/2.1.0/gems/railties-4.2.1/lib/rails/commands/commands_tasks.rb:39:in
`run_command!'
  from
/var/lib/gems/2.1.0/gems/railties-4.2.1/lib/rails/commands.rb:17:in
`<top (required)>'
  from /home/andika/andikanug/bin/rails:8:in `require'
  from /home/andika/andikanug/bin/rails:8:in `<top (required)>'
  from
/var/lib/gems/2.1.0/gems/spring-1.3.4/lib/spring/client/rails.rb:28:in
`load'
  from
/var/lib/gems/2.1.0/gems/spring-1.3.4/lib/spring/client/rails.rb:28:in
`call'
  from
/var/lib/gems/2.1.0/gems/spring-1.3.4/lib/spring/client/command.rb:7:in
`call'
  from /var/lib/gems/2.1.0/gems/spring-1.3.4/lib/spring/client.rb:26:in
`run'
  from /var/lib/gems/2.1.0/gems/spring-1.3.4/bin/spring:48:in `<top
(required)>'
  from /var/lib/gems/2.1.0/gems/spring-1.3.4/lib/spring/binstub.rb:11:in
`load'
  from /var/lib/gems/2.1.0/gems/spring-1.3.4/lib/spring/binstub.rb:11:in
`<top (required)>'
  from /usr/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in
`require'
  from /usr/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in
`require'
  from /home/andika/andikanug/bin/spring:13:in `<top (required)>'
  from bin/rails:3:in `load'
  from bin/rails:3:in `<main>'
andika@andika-HP:~/andikanug$

Either install nodejs
sudo apt-get install nodejs
or include in Gemfile
gem 'execjs'
gem 'therubyracer'

Colin

And I didn't even say you should have googled for the error message.

Don't forget to do
bundle install
after changing Gemfile, and if you are a beginner to Rails then start
by working right through a good tutorial such as railstutorial.org,
which is free to use online.

Colin

Andika, that is for you: http://www.catb.org/esr/faqs/smart-questions.html