Rails 控制台：在“require”中：无法加载此类文件 — readline (LoadError)

Question

我的 Rails 应用程序出现了一些错误，我正在尝试通过发出以下命令来启动 Rails 控制台：

rails console

无论我尝试什么，我总是遇到相同的错误：

/usr/local/rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/irb/completion.rb:9:in `require': cannot load such file -- readline (LoadError)
    from /usr/local/rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/irb/completion.rb:9:in `<top (required)>'
    from /opt/mammie/web/icosole/vendor/bundle/ruby/2.1.0/gems/railties-3.1.3/lib/rails/commands/console.rb:3:in `require'
    from /opt/mammie/web/icosole/vendor/bundle/ruby/2.1.0/gems/railties-3.1.3/lib/rails/commands/console.rb:3:in `<top (required)>'
    from /opt/mammie/web/icosole/vendor/bundle/ruby/2.1.0/gems/railties-3.1.3/lib/rails/commands.rb:37:in `require'
    from /opt/mammie/web/icosole/vendor/bundle/ruby/2.1.0/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>'

我真的尝试了我在网上找到的所有可能的解决方案，因为很多人都遇到了同样的错误。 不幸的是，似乎没有任何效果。 当我尝试以下命令时：

ruby /usr/local/rvm/src/ruby-2.1.1/ext/readline/extconf.rb

我得到以下输出

checking for tgetnum() in -lncurses... yes
checking for readline/readline.h... yes
checking for readline/history.h... yes
checking for readline() in -lreadline... no
checking for readline() in -ledit... no
checking for editline/readline.h... no
*** /usr/local/rvm/src/ruby-2.1.1/ext/readline/extconf.rb failed ***

表示缺少某些内容，但使用 apt-get 安装 readline 也没有任何区别。 我猜这可能与不兼容的 gem 版本有关，因为控制台前段时间工作过短暂。 readline 是否存在任何已知的版本问题？ 很多人似乎都遇到过这个 gem 的问题。

Answer 1

尝试将rb-readline放在您的 Gemfile 中并查看https://stackoverflow.com/a/9595841/1905235

Answer 2

我终于找到了解决方案。 这是几个问题的结合（gem 版本，冲突的 readline 库）。

首先，我重新获取了 readline 库

sudo apt-get install libreadline-dev

然后我卸载了ruby

rvm remove 2.1.1

我再次安装了 ruby

rvm install 2.1.1

我告诉 RVM 使用默认的 (2.1.1) Ruby

rvm use default

我重新安装了 Rails 和 readline

gem install rails
gem install readline

我再次启动控制台时出现错误，但略有不同：

/usr/local/rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/irb/completion.rb:9:in `require':  /usr/local/lib/libreadline.so.6: undefined symbol: UP - /usr/local/rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/x86_64-linux/readline.so (LoadError)
    from /usr/local/rvm/rubies/ruby-2.1.1/lib/ruby/2.1.0/irb/completion.rb:9:in `<top (required)>'
    from /opt/mammie/web/icosole/vendor/bundle/ruby/2.1.0/gems/railties-3.1.3/lib/rails/commands/console.rb:3:in `require'
    from /opt/mammie/web/icosole/vendor/bundle/ruby/2.1.0/gems/railties-3.1.3/lib/rails/commands/console.rb:3:in `<top (required)>'
    from /opt/mammie/web/icosole/vendor/bundle/ruby/2.1.0/gems/railties-3.1.3/lib/rails/commands.rb:37:in `require'
    from /opt/mammie/web/icosole/vendor/bundle/ruby/2.1.0/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>'

所以按照这个说明（ http://vkarthickeyan.wordpress.com/2012/02/16/mysql-symbol-lookup-error-usrlocalliblibreadline-so-6-undefined-symbol-up/ ），我让它工作：

cd /usr/local/lib
mkdir temp
mv libreadline* temp
ldconfig
apt-get update

感谢 Hunterboerner 的帮助！

Answer 3

如果您运行的是Rails 4.x ，则可能是Spring导致了这个问题。

尝试停止 Spring 进程bundle exec spring stop

然后运行bundle exec rails c

Answer 4

这在没有 readline 的 Solaris 机器上运行正常，可能对您有用：

$ bundle exec irb
irb(main):001:0> require File.expand_path('config/boot')
=> true
irb(main):002:0> require File.expand_path('config/environment')
NOTE: Gem.source_index is deprecated, use Specification. It will be removed on or after 2011-11-01.
Gem.source_index called from /export/home/deploy/recon/shared/bundle/ruby/1.8/gems/rails-2.3.18/lib/rails/gem_dependency.rb:21.
Warning: NLS_LANG is not set. fallback to US7ASCII.
=> true
irb(main):027:0> require 'console_app'
=> true

Answer 5

rvm requirements我遇到了这个问题，通过键入以下rvm requirements解决： rvm requirements并安装返回的内容。 似乎，虽然这是 rvm 的旧版本，因此可能不再相关

Answer 6

rvm reinstall 2.7.0

为我工作