no such file to load -- readline解决办法

升级ruby和rails后进入script/consle出现：

/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

/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

解决办法：
  第一步：确认是否安装了libncurses5-dev libreadline5-dev ,如果没有安装，就用
   sudo apt-get install libncurses5-dev libreadline5-dev 进行安装
  第二步：

1. cd /usr/src/ruby-1.8.7/ext/readline
2. ruby extconf.rb
3. make
4. sudo make install

 1. cd /usr/src/ruby-1.8.7/ext/readline 2. ruby extconf.rb 3. make 4. sudo make install