升級ruby和rails后進入script/consle出現：
代碼如下:
/usr/local/lib/ruby/1.8/irb/completion.rb:10:in `require': no such file to load -- readline (LoadError) 
        from /usr/local/lib/ruby/1.8/irb/completion.rb:10 
        from /usr/local/lib/ruby/1.8/irb/init.rb:252:in `require' 
        from /usr/local/lib/ruby/1.8/irb/init.rb:252:in `load_modules' 
        from /usr/local/lib/ruby/1.8/irb/init.rb:250:in `each' 
        from /usr/local/lib/ruby/1.8/irb/init.rb:250:in `load_modules' 
        from /usr/local/lib/ruby/1.8/irb/init.rb:21:in `setup' 
        from /usr/local/lib/ruby/1.8/irb.rb:54:in `start' 
        from /usr/local/bin/irb:13 

解決辦法：

第一步：確認是否安裝了libncurses5-dev libreadline5-dev ,如果沒有安裝，就用 
代碼如下:
   sudo apt-get install libncurses5-dev libreadline5-dev 進行安裝 

第二步： 
代碼如下:
cd /usr/src/ruby-1.8.7/ext/readline 
ruby extconf.rb 
make 
sudo make install