Command 'qmake -spec linux-g++ ' not available during installation of capybara

Error:

Installing capybara (2.2.1)

Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

    /home/sachin/.rvm/rubies/ruby-2.0.0-p353/bin/ruby extconf.rb 
Command 'qmake -spec linux-g++ ' not available

Makefile not found

Gem files will remain installed in /home/sachin/.rvm/gems/ruby-2.0.0-p353@popuptelent/gems/capybara-webkit-1.1.0 for inspection.
Results logged to /home/sachin/.rvm/gems/ruby-2.0.0-p353@popuptelent/extensions/x86_64-linux/2.0.0/capybara-webkit-1.1.0/gem_make.out
An error occurred while installing capybara-webkit (1.1.0), and Bundler cannot continue.
Make sure that `gem install capybara-webkit -v '1.1.0'` succeeds before bundling.

Solution:

If you are using Ubuntu OS then run this command

sudo apt-get install qt4-dev-tools libqt4-dev libqt4-core libqt4-gui

If you are using Mac OS then run this command

brew install qt

and then run this command for install gem for capybara-webkit

gem install capybara-webkit -v '1.1.0'