我在机器上的导轨上设置ruby时遇到问题。我一直在关注“使用Rails进行敏捷Web开发”一书，直到现在一切都很顺利。
我遇到的问题是当我输入
时rails server
我收到以下错误：
/home/myname/.gem/ruby/1.9.1/gems/execjs-1.3.0/lib/execjs/runtimes.rb:50:in `autodetect': Could not find a JavaScript runtime. See https://github.com/sstephenson/execjs for a list of available runtimes. (ExecJS::RuntimeUnavailable)
from /home/myname/.gem/ruby/1.9.1/gems/execjs-1.3.0/lib/execjs.rb:5:in `<module:ExecJS>'
from /home/myname/.gem/ruby/1.9.1/gems/execjs-1.3.0/lib/execjs.rb:4:in `<top (required)>'
from /usr/lib/ruby/gems/1.9.1/gems/coffee-script-2.2.0/lib/coffee_script.rb:1:in `require'
from /usr/lib/ruby/gems/1.9.1/gems/coffee-script-2.2.0/lib/coffee_script.rb:1:in `<top (required)>'
from /usr/lib/ruby/gems/1.9.1/gems/coffee-script-2.2.0/lib/coffee-script.rb:1:in `require'
from /usr/lib/ruby/gems/1.9.1/gems/coffee-script-2.2.0/lib/coffee-script.rb:1:in `<top (required)>'
from /usr/lib/ruby/gems/1.9.1/gems/coffee-rails-3.2.2/lib/coffee-rails.rb:1:in `require'
from /usr/lib/ruby/gems/1.9.1/gems/coffee-rails-3.2.2/lib/coffee-rails.rb:1:in `<top (required)>'
from /home/myname/.gem/ruby/1.9.1/gems/bundler-1.1.0/lib/bundler/runtime.rb:68:in `require'
from /home/myname/.gem/ruby/1.9.1/gems/bundler-1.1.0/lib/bundler/runtime.rb:68:in `block (2 levels) in require'
from /home/myname/.gem/ruby/1.9.1/gems/bundler-1.1.0/lib/bundler/runtime.rb:66:in `each'
from /home/myname/.gem/ruby/1.9.1/gems/bundler-1.1.0/lib/bundler/runtime.rb:66:in `block in require'
from /home/myname/.gem/ruby/1.9.1/gems/bundler-1.1.0/lib/bundler/runtime.rb:55:in `each'
from /home/myname/.gem/ruby/1.9.1/gems/bundler-1.1.0/lib/bundler/runtime.rb:55:in `require'
from /home/myname/.gem/ruby/1.9.1/gems/bundler-1.1.0/lib/bundler.rb:118:in `require'
from /home/myname/Programming/Learning/Learning_Rails/demo/config/application.rb:7:in `<top (required)>'
from /home/myname/.gem/ruby/1.9.1/gems/railties-3.2.2/lib/rails/commands.rb:53:in `require'
from /home/myname/.gem/ruby/1.9.1/gems/railties-3.2.2/lib/rails/commands.rb:53:in `block in <top (required)>'
from /home/myname/.gem/ruby/1.9.1/gems/railties-3.2.2/lib/rails/commands.rb:50:in `tap'
from /home/myname/.gem/ruby/1.9.1/gems/railties-3.2.2/lib/rails/commands.rb:50:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'
它说无法找到javascript运行时环境。我去了错误消息推荐的网站，我做了一些谷歌搜索，我读到execjs将是一个很好的选择安装。我使用以下命令安装了execjs：
sudo gem install execjs
sudo gem update
当我运行'gem list'时，我得到以下输出：
*** LOCAL GEMS ***
actionmailer (3.2.2)
actionpack (3.2.2)
activemodel (3.2.2)
activerecord (3.2.2)
activeresource (3.2.2)
activesupport (3.2.2)
arel (3.0.2)
bigdecimal (1.1.0)
builder (3.0.0)
bundler (1.1.0)
coffee-rails (3.2.2)
coffee-script (2.2.0)
coffee-script-source (1.2.0)
erubis (2.7.0)
execjs (1.3.0 ruby)
hike (1.2.1)
i18n (0.6.0)
io-console (0.3)
journey (1.0.3)
jquery-rails (2.0.1)
json (1.6.5, 1.5.4)
mail (2.4.3)
mime-types (1.17.2)
minitest (2.11.3, 2.5.1)
multi_json (1.1.0)
polyglot (0.3.3)
rack (1.4.1)
rack-cache (1.2)
rack-ssl (1.3.2)
rack-test (0.6.1)
rails (3.2.2)
railties (3.2.2)
rake (0.9.2.2)
rdoc (3.12, 3.9.4)
sass (3.1.15)
sass-rails (3.2.4)
sprockets (2.3.1, 2.1.2)
sqlite3 (1.3.5)
thor (0.14.6)
tilt (1.3.3)
treetop (1.4.10)
tzinfo (0.3.32)
uglifier (1.2.3)
从上面的输出看起来像我安装了execjs。这里发生了什么，为什么我会收到此错误？
如果它有用，
我的操作系统是Arch Linux。
ruby -v：ruby 1.9.3p125（2012-02-16修订版34643）[x86_64-linux]
rails -v：Rails 3.2.2
任何帮助都将不胜感激。
答案 0 :(得分：11)
您的Gemfile应包含以下几行：
gem 'execjs'
gem 'therubyracer'
然后运行bundle install并重试。
答案 1 :(得分：5)
如果你要添加therubyracer宝石，可能会解决你的问题
代码
gem 'therubyracer'
gem 'execjs'
然后只做一个bundle install
答案 2 :(得分：3)
试试这个：
$ sudo apt-get install nodejs
答案 3 :(得分：1)
我认为你需要像rubyracer这样的运行时。 尝试
sudo gem install therubyracer
答案 4 :(得分：1)
如果您正在使用Pacman包管理器，则应使用：
# pacman -S nodejs
或
$ sudo pacman -S nodejs
答案 5 :(得分：0)
我在Rails之前安装了Node.js.现在它使用Node.js作为javascript运行时。
JavaScript Runtime Node.js (V8)