出现错误要先看提示代码，知道错在哪里，如：

dong@ubuntu:~/octopress$ rake generate
## Generating Site with Jekyll
identical source/stylesheets/screen.css 
/home/dong/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/psych.rb:203:in `parse': (/home/dong/octopress/_config.yml): could not find expected ':' while scanning a simple key at line 10 column 1 (Psych::SyntaxError)
    from /home/dong/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/psych.rb:203:in `parse_stream'
    from /home/dong/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/psych.rb:151:in `parse'
    from /home/dong/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/psych.rb:127:in `load'
    from /home/dong/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/psych.rb:297:in `block in load_file'
    from /home/dong/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/psych.rb:297:in `open'
    from /home/dong/.rvm/rubies/ruby-1.9.3-p448/lib/ruby/1.9.1/psych.rb:297:in `load_file'
    from /home/dong/.rvm/gems/ruby-1.9.3-p448/gems/jekyll-0.12.0/lib/jekyll.rb:130:in `configuration'
    from /home/dong/.rvm/gems/ruby-1.9.3-p448/gems/jekyll-0.12.0/bin/jekyll:221:in `<top (required)>'
    from /home/dong/.rvm/gems/ruby-1.9.3-p448/bin/jekyll:23:in `load'
    from /home/dong/.rvm/gems/ruby-1.9.3-p448/bin/jekyll:23:in `<main>'
    from /home/dong/.rvm/gems/ruby-1.9.3-p448/bin/ruby_executable_hooks:15:in `eval'
    from /home/dong/.rvm/gems/ruby-1.9.3-p448/bin/ruby_executable_hooks:15:in `<main>'

代码已经说得很清楚了，就是/home/dong/octopress/_config.yml，这个文件，could not find expected ‘:’ while scanning a simple key at line 10 column 1 (Psych::SyntaxError)
就是'：'后面忘了加空格