xxxxxx@MacBook ~ % gem -v
/Users/xxxxxx/.rbenv/versions/truffleruby-20.1.0/lib/mri/rubygems/core_ext/kernel_require.rb:54:in `gem_original_require': Library "/usr/lib/libSystem.B.dylib" does not exist. (RuntimeError)
  from /Users/xxxxxx/.rbenv/versions/truffleruby-20.1.0/lib/mri/rubygems/core_ext/kernel_require.rb:54:in `require'
  from /Users/xxxxxx/.rbenv/versions/truffleruby-20.1.0/lib/mri/rubygems/config_file.rb:71:in `ConfigFile'
  from /Users/xxxxxx/.rbenv/versions/truffleruby-20.1.0/lib/mri/rubygems/config_file.rb:39:in `<top (required)>'
  from /Users/xxxxxx/.rbenv/versions/truffleruby-20.1.0/lib/mri/rubygems/core_ext/kernel_require.rb:54:in `gem_original_require'
  from /Users/xxxxxx/.rbenv/versions/truffleruby-20.1.0/lib/mri/rubygems/core_ext/kernel_require.rb:54:in `require'
  from /Users/xxxxxx/.rbenv/versions/truffleruby-20.1.0/lib/mri/rubygems/gem_runner.rb:10:in `<top (required)>'
  from /Users/xxxxxx/.rbenv/versions/truffleruby-20.1.0/lib/mri/rubygems/core_ext/kernel_require.rb:54:in `gem_original_require'
  from /Users/xxxxxx/.rbenv/versions/truffleruby-20.1.0/lib/mri/rubygems/core_ext/kernel_require.rb:54:in `require'
  from /Users/xxxxxx/.rbenv/versions/truffleruby-20.1.0/bin/gem:27:in `<main>'

今天在更新项目的pod库，经历版本冲突卸载重装各种操作之后，在执行gem命令时，一直提示以上错误，我解决的办法是，删除了/Users/xxxxxx/.rbenv文件夹，而这个文件夹默认是隐藏的