以下のエラーで
cygwinでruby gems が実行できない
$ gem install selenium-webdriver
ERROR: Loading command: install (Fiddle::DLError)
can't load kernel32
ERROR: While executing gem ... (NoMethodError)
undefined method `invoke_with_build_args' for nil:NilClass
ln -s /cygdrive/c/Windows/System32/kernel32.dll /usr/lib/kernel32
gem install selenium-webdriver
https://superuser.com/questions/1093954/gem-not-working-in-cygwin