How can I avoid this warning?

NOTE: Gem::Specification#default_executable= is deprecated with no
replacement. It will be removed on or after 2011-10-01.
Gem::Specification#default_executable= called from
/usr/local/lib/ruby/gems/1.9.1/specifications/rubygems-update-1.7.2.gemspec:11.

Please anyone explain…

Thanks and Regards…

It’s probably from the upgrade to RubyGems 1.8.x. You shouldn’t need any
copies of rubygems-update around after updating, so you can just:

gem uninstall rubygems-update
and you won’t see that particular warning anymore.

If you still see it for other gems, the outdated methods will need to be
removed from their gemspecs and new versions released.

Adam S.