title: Ruby Debugger installation Error
body: <p>I am getting the following Error While installing ruby debugger</p>
  
  <p>In gemfile i added</p>
  
  <pre><code> gem 'ruby-debug19', :require =&gt; 'ruby-debug'
  </code></pre>
  
  <p>and run </p>
  
  <pre><code> bundle install
  
  Installing linecache19 (0.5.12) with native extensions
     Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.
     /usr/local/bin/ruby extconf.rb
     checking for vm_core.h... no
     checking for vm_core.h... no
     *** 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=/usr/local/bin/ruby
     --with-ruby-dir
     --without-ruby-dir
     --with-ruby-include
     --without-ruby-include=${ruby-dir}/include
     --with-ruby-lib
     --without-ruby-lib=${ruby-dir}/lib
  </code></pre>
  
  <p>What is the reason for the error </p>
  
  <p>how to install thre debugger..???</p>