Uninstall old versions of Ruby gems
Way to clean out any old versions of gems.
sudo gem cleanup
If you just want to see a list of what would be removed you can use:
sudo gem cleanup -d
You can also cleanup just a specific gem by specifying its name:
sudo gem cleanup gemname
for remove specific version like 1.1.9 only
gem uninstall gemname --version 1.1.9
If you still facing some exception to install gem, like:
invalid gem: package is corrupt, exception while verifying: undefined method `size' for nil:NilClass (NoMethodError) in /home/rails/.rvm/gems/ruby-2.1.1@project/cache/nokogiri-1.6.6.2.gem
the, you can remove it from cache:
rm /home/rails/.rvm/gems/ruby-2.1.1@project/cache/nokogiri-1.6.6.2.gem
For more detail:
http://blog.grepruby.com/2015/04/way-to-clean-up-gem-or-remove-old.html