最近我安装了rbenv，并将ruby指定为2.3.1，将rails指定为5.1.1，但我无法运行我的项目，因为我得到了：
Ignoring json-2.1.0 because its extensions are not built. Try: gem pristine json --version 2.1.0
Ignoring nokogiri-1.8.1 because its extensions are not built. Try: gem pristine nokogiri --version 1.8.1
Ignoring unf_ext-0.0.7.4 because its extensions are not built. Try: gem pristine unf_ext --version 0.0.7.4
Ignoring yajl-ruby-1.3.1 because its extensions are not built. Try: gem pristine yajl-ruby --version 1.3.1
/var/lib/gems/2.3.0/gems/bundler-1.16.1/lib/bundler/spec_set.rb:88:in `block in materialize': Could not find unf_ext-0.0.7.4 in any of the sources (Bundler::GemNotFound)
from /var/lib/gems/2.3.0/gems/bundler-1.16.1/lib/bundler/spec_set.rb:82:in `map!'
...
from /home/alex/pnv/vendor/bundle/ruby/2.3.0/gems/spring-2.0.2/bin/spring:49:in `<main>'
我运行了：
bundle install
安装成功通过，但。。。现在我得到：
/home/alex/pnv/vendor/bundle/ruby/2.3.0/gems/ffi-1.9.18/lib/ffi.rb:6:in `require': incompatible library version - /home/alex/pnv/vendor/bundle/ruby/2.3.0/gems/ffi-1.9.18/lib/ffi_c.so (LoadError)
from /home/alex/pnv/vendor/bundle/ruby/2.3.0/gems/ffi-1.9.18/lib/ffi.rb:6:in `rescue in <top (required)>'
from /home/alex/pnv/vendor/bundle/ruby/2.3.0/gems/ffi-1.9.18/lib/ffi.rb:3:in `<top (required)>'
from /home/alex/pnv/vendor/bundle/ruby/2.3.0/gems/rb-inotify-0.9.8/lib/rb-inotify/native.rb:1:in `require'
from /home/alex/pnv/vendor/bundle/ruby/2.3.0/gems/rb-inotify-0.9.8/lib/rb-inotify/native.rb:1:in `<top (required)>'
from /home/alex/pnv/vendor/bundle/ruby/2.3.0/gems/rb-inotify-0.9.8/lib/rb-inotify.rb:1:in `require'
from /home/alex/pnv/vendor/bundle/ruby/2.3.0/gems/rb-inotify-0.9.8/lib/rb-inotify.rb:1:in `<top (required)>'
from /home/alex/pnv/vendor/bundle/ruby/2.3.0/gems/listen-3.0.8/lib
...
from /home/alex/.rbenv/versions/2.3.1/lib/ruby/site_ruby/2.3.0/rubygems/core_ext/kernel_require.rb:59:in `require'
from -e:1:in `<main>'
我不知道如何解决这个问题。感谢您的帮助！
更新1：最后，我找到了这个邪恶bug的来源——尽管如此，我指定了Rails 5.1.1，当我运行Rails-new app_name时，它会安装5.1.6！它似乎使用了5.1.6的gem依赖项。。。仍然不知道如何解决而不是升级到>=5.1.6
将以下行添加到Gemfile中。
gem 'rails', '5.1.1'
运行bundle install