Ruby Debugger installation Error - ruby-on-rails

Question

I am getting the following Error While installing ruby debugger
In gemfile i added
gem 'ruby-debug19', :require => 'ruby-debug'
and run
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
What is the reason for the error
how to install thre debugger..???

Answer 1

You have to first set the path of DevKit in your environmental variable
Then run
gem install linecache19
gem install ruby-debug-base19
gem install ruby-debug-ide
through command prompt
May this work

Answer 2

From the RVM website:
If you have trouble installing ruby-debug19 try installing with the following command:
$ rvm reinstall 1.9.3 --patch debug --force-autoconf
$ gem install ruby-debug19 -- --with-ruby-include="${MY_RUBY_HOME/rubies/src}"

Answer 3

"On Ubuntu, the native compilation step downloads the ruby 1.9.2 source and tries to unpack it into a directory that your current user probably does not have write access to." - Darren (Reference: http://isitruby19.com/linecache19)
In this case, try sudo bundle install.
If the problem is that it cannot resolve the vm_core.h file dependency, you can run the installs with specific versions and the path to the ruby source:
sudo -E gem install linecache19 -v=0.5.11 -- --with-ruby-include=path_to/ruby-1.9.1-p378/
sudo -E gem install ruby-debug-base19 -v=0.11.23 -- --with-ruby-include=path_to/ruby-1.9.1-p378/
sudo -E gem install ruby-debug-ide -v=0.4.9 -- --with-ruby-include=path_to/ruby-1.9.1-p378/
Reference: http://isitruby19.com/linecache19
Note, replace path_to/ruby-1.9.1-p378/, with the path to where you installed ruby.
To find out where you installed ruby, try running:
which ruby