【发布时间】：2014-07-07 18:57:27
【问题描述】：
尝试安装gem rubyracer 和gem execjs，原因我不记得了。
可能是因为我正在尝试部署一个在服务器上显示存在重大问题的 jekyll 站点。
所以，尝试运行jekyll --server
得到这个错误：
/usr/local/rvm/gems/ruby-2.1.2/gems/execjs-2.2.1/lib/execjs/runtimes.rb:51:in `autodetect': Could not find a JavaScript runtime. See https://github.com/sstephenson/execjs for a list of available runtimes. (ExecJS::RuntimeUnavailable)
from /usr/local/rvm/gems/ruby-2.1.2/gems/execjs-2.2.1/lib/execjs.rb:5:in `<module:ExecJS>'
from /usr/local/rvm/gems/ruby-2.1.2/gems/execjs-2.2.1/lib/execjs.rb:4:in `<top (required)>'
from /usr/local/rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /usr/local/rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /usr/local/rvm/gems/ruby-2.1.2/gems/coffee-script-2.2.0/lib/coffee_script.rb:1:in `<top (required)>'
from /usr/local/rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /usr/local/rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /usr/local/rvm/gems/ruby-2.1.2/gems/coffee-script-2.2.0/lib/coffee-script.rb:1:in `<top (required)>'
from /usr/local/rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /usr/local/rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /usr/local/rvm/gems/ruby-2.1.2/gems/jekyll-coffeescript-1.0.0/lib/jekyll-coffeescript.rb:2:in `<top (required)>'
from /usr/local/rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /usr/local/rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /usr/local/rvm/gems/ruby-2.1.2/gems/jekyll-2.1.0/lib/jekyll.rb:75:in `<top (required)>'
from /usr/local/rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /usr/local/rvm/rubies/ruby-2.1.2/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /usr/local/rvm/gems/ruby-2.1.2/gems/jekyll-2.1.0/bin/jekyll:6:in `<top (required)>'
from /usr/local/rvm/gems/ruby-2.1.2/bin/jekyll:23:in `load'
from /usr/local/rvm/gems/ruby-2.1.2/bin/jekyll:23:in `<main>'
from /usr/local/rvm/gems/ruby-2.1.2/bin/ruby_executable_hooks:15:in `eval'
from /usr/local/rvm/gems/ruby-2.1.2/bin/ruby_executable_hooks:15:in `<main>'
因此，rubyracer 和 execjs 的安装尝试
这是我尝试安装它们时得到的结果（两者的消息相同）：
/usr/local/rvm/rubies/ruby-2.1.2/bin/gem:8:in `require': no such file to load -- rubygems (LoadError)
from /usr/local/rvm/rubies/ruby-2.1.2/bin/gem:8
环境是linux服务器。不是我的笔记本电脑。
其他信息
which jekyll 得到这个：/usr/local/rvm/gems/ruby-2.1.2/bin/jekyll
echo $PATH 得到这个：
/usr/local/rvm/gems/ruby-2.1.2/bin:/usr/local/rvm/gems/ruby-2.1.2@global/bin:/usr/local/rvm/rubies/ruby-2.1.2/bin:/usr/kerberos/bin:/usr/local/bin:/bin:/usr/bin:/usr/local/rvm/bin:/home/coffee/bin
ruby -v 得到这个：ruby 2.1.2p95 (2014-05-08 revision 45877) [i686-linux]
which ruby 得到这个：usr/local/rvm/rubies/ruby-2.1.2/bin/ruby
【问题讨论】：