2.安装 imagemagick  （linux下）

$ sudo apt-get install imagemagick

3.编辑Gemfile 文件

gem 'carrierwave'
gem 'mini_magick'
gem 'ckeditor'

4.在终端中输入

$ rails generate ckeditor:install --orm=active_record --backend=carrierwave

5.在application.js 或者 application.js.erb文件中：

//= require ckeditor/init

6.在终端中输入

$ bundle exec rake db:migrate

7.在对应的编辑页面中引用ckeditor编辑器

<%= form_for @article do |f| %>
  <%= f.cktext_area :introduction %>
<% end %>

注意，做完上面几步, ckeditor是出来了,但是还没有 "上传文件" 这个功能

add this file to : app/assets/javascripts/ckeditor/config.js

/*
Copyright (c) 2003-2011, CKSource - Frederico Knabben. All rights reserved.
For licensing, see LICENSE.html or http://ckeditor.com/license
*/

CKEDITOR.editorConfig = function( config )
{
  // Define changes to default configuration here. For example:
  config.language = 'zh-CN';
  config.height='600px';
  // config.uiColor = '#AADC6E';

  /* Filebrowser routes */
  // The location of an external file browser, that should be launched when "Browse Server" button is pressed.
  config.filebrowserBrowseUrl = "/ckeditor/attachment_files";

  // The location of an external file browser, that should be launched when "Browse Server" button is pressed in the Flash dialog.
  config.filebrowserFlashBrowseUrl = "/ckeditor/attachment_files";

  // The location of a script that handles file uploads in the Flash dialog.
  config.filebrowserFlashUploadUrl = "/ckeditor/attachment_files";

  // The location of an external file browser, that should be launched when "Browse Server" button is pressed in the Link tab of Image dialog.
  config.filebrowserImageBrowseLinkUrl = "/ckeditor/pictures";

  // The location of an external file browser, that should be launched when "Browse Server" button is pressed in the Image dialog.
  config.filebrowserImageBrowseUrl = "/ckeditor/pictures";

  // The location of a script that handles file uploads in the Image dialog.
  config.filebrowserImageUploadUrl = "/ckeditor/pictures";

  // The location of a script that handles file uploads.
  config.filebrowserUploadUrl = "/ckeditor/attachment_files";

  // Rails CSRF token
  config.filebrowserParams = function(){
    var csrf_token, csrf_param, meta,
        metas = document.getElementsByTagName('meta'),
        params = new Object();

    for ( var i = 0 ; i < metas.length ; i++ ){
      meta = metas[i];

      switch(meta.name) {
        case "csrf-token":
          csrf_token = meta.content;
          break;
        case "csrf-param":
          csrf_param = meta.content;
          break;
        default:
          continue;
      }
    }

    if (csrf_param !== undefined && csrf_token !== undefined) {
      params[csrf_param] = csrf_token;
    }

    return params;
  };

  config.addQueryString = function( url, params ){
    var queryString = [];

    if ( !params ) {
      return url;
    } else {
      for ( var i in params )
        queryString.push( i + "=" + encodeURIComponent( params[ i ] ) );
    }

    return url + ( ( url.indexOf( "?" ) != -1 ) ? "&" : "?" ) + queryString.join( "&" );
  };

  // Integrate Rails CSRF token into file upload dialogs (link, image, attachment and flash)
  CKEDITOR.on( 'dialogDefinition', function( ev ){
    // Take the dialog name and its definition from the event data.
    var dialogName = ev.data.name;
    var dialogDefinition = ev.data.definition;
    var content, upload;

    if (CKEDITOR.tools.indexOf(['link', 'image', 'attachment', 'flash'], dialogName) > -1) {
      content = (dialogDefinition.getContents('Upload') || dialogDefinition.getContents('upload'));
      upload = (content == null ? null : content.get('upload'));

      if (upload && upload.filebrowser && upload.filebrowser['params'] === undefined) {
        upload.filebrowser['params'] = config.filebrowserParams();
        upload.action = config.addQueryString(upload.action, upload.filebrowser['params']);
      }
    }
  });
};

之后就可以在页面中看到ckeditor 编辑器了。

参考（web.siwei.tech）