linux上进入rails console提示cannot load such file - readline
在linux下输入rails console，之后提示错误，如下：
/usr/local/ruby/lib/ruby/1.9.1/irb/completion.rb:9:in `require': cannot load such file -- readline (LoadError)
from /usr/local/ruby/lib/ruby/1.9.1/irb/completion.rb:9:in `<top (required)>'
from /usr/local/ruby/lib/ruby/gems/1.9.1/gems/railties-3.1.3/lib/rails/commands/console.rb:3:in `require'
from /usr/local/ruby/lib/ruby/gems/1.9.1/gems/railties-3.1.3/lib/rails/commands/console.rb:3:in `<top (required)>'
from /usr/local/ruby/lib/ruby/gems/1.9.1/gems/railties-3.1.3/lib/rails/commands.rb:37:in `require'
from /usr/local/ruby/lib/ruby/gems/1.9.1/gems/railties-3.1.3/lib/rails/commands.rb:37:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'
需要先安装readline，命令如下：
apt-get install libreadline5-dev
再进入到ruby源码中，重新编译readline，命令如下：
cd ext/readline ruby extconf.rb make sudo make install
即可。