$gem install ruby-debug

Fetching: columnize-0.3.6.gem (100%) Successfully installed columnize-0.3.6 Fetching: rbx-require-relative-0.0.9.gem (100%) Successfully installed rbx-require-relative-0.0.9 Fetching: linecache-0.46.gem (100%) Building native extensions. This could take a while... ERROR: Error installing ruby-debug: ERROR: Failed to build gem native extension.

/home/wangliang/.rvm/rubies/ruby-2.0.0-p247/bin/ruby extconf.rb Can't handle 1.9.x yet *** extconf.rb failed *** Could not create Makefile due to some reason, probably lack of necessary libraries and/or headers. Check the mkmf.log file for more details. You may need configuration options.

Provided configuration options: --with-opt-dir --without-opt-dir --with-opt-include --without-opt-include=${opt-dir}/include --with-opt-lib --without-opt-lib=${opt-dir}/lib --with-make-prog --without-make-prog --srcdir=. --curdir --ruby=/home/wangliang/.rvm/rubies/ruby-2.0.0-p247/bin/ruby

Gem files will remain installed in /home/wangliang/.rvm/gems/ruby-2.0.0-p247/gems/linecache-0.46 for inspection. Results logged to /home/wangliang/.rvm/gems/ruby-2.0.0-p247/gems/linecache-0.46/ext/gem_make.out