動作環境
$ cat /etc/`ls /etc -F | grep "release$\|version$"` CentOS release 6.4 (Final) $ rails -v Rails 4.0.0 $ ruby -v ruby 1.9.3p448 (2013-06-27 revision 41675) [x86_64-linux]
事象
rails consoleコマンドを打つと以下のようなエラーが出ました。
$ rails c ... /usr/local/rbenv/versions/1.9.3-p448/lib/ruby/1.9.1/irb/completion.rb:9:in `require': cannot load such file -- readline (LoadError) from /usr/local/rbenv/versions/1.9.3-p448/lib/ruby/1.9.1/irb/completion.rb:9:in `<top (required)>' from /usr/local/rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/railties-4.0.0/lib/rails/commands/console.rb:3:in `require' from /usr/local/rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/railties-4.0.0/lib/rails/commands/console.rb:3:in `<top (required)>' from /usr/local/rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/railties-4.0.0/lib/rails/commands.rb:53:in `require' from /usr/local/rbenv/versions/1.9.3-p448/lib/ruby/gems/1.9.1/gems/railties-4.0.0/lib/rails/commands.rb:53:in `<top (required)>' from bin/rails:4:in `require' from bin/rails:4:in `<main>'
対処法
gemで必要なライブラリをインストールします。 Gemfileに以下を追記します。
gem 'rb-readline'
実行すると次は違うエラーが出ます。
$ rails c ... uninitialized constant IRB::ReadlineInputMethod::Readline (NameError) ...
これはライブラリのバージョンを指定してあげると解消します。
gem 'rb-readline', '~> 0.4.2'
$ rails c Loading development environment (Rails 4.0.0) irb(main):001:0>