我想安装gem capybara-webkit 但是当我运行bundle install时，我收到以下错误：
Gem::Ext::BuildError: ERROR: Failed to build gem native extension.
/home/dineshp/.rvm/rubies/ruby-2.2.1/bin/ruby -r ./siteconf20160814-4696-3d7ixk.rb extconf.rb
*** 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/dineshp/.rvm/rubies/ruby-2.2.1/bin/$(RUBY_BASE_NAME)
--with-gl-dir
--without-gl-dir
--with-gl-include
--without-gl-include=${gl-dir}/include
--with-gl-lib
--without-gl-lib=${gl-dir}/lib
--with-zlib-dir
--without-zlib-dir
--with-zlib-include
--without-zlib-include=${zlib-dir}/include
--with-zlib-lib
--without-zlib-lib=${zlib-dir}/lib
Command 'qmake ' not available
extconf failed, exit code 1
Gem files will remain installed in /home/dineshp/.rvm/gems/ruby-2.2.1@rails420/gems/capybara-webkit-1.11.1 for inspection.
Results logged to /home/dineshp/.rvm/gems/ruby-2.2.1@rails420/extensions/x86_64-linux/2.2.0/capybara-webkit-1.11.1/gem_make.out
An error occurred while installing capybara-webkit (1.11.1), and Bundler cannot continue.
Make sure that `gem install capybara-webkit -v '1.11.1'` succeeds before bundling.
由于上述错误显示：命令＆＃39; qmake＆＃39;不可用，我在引用this后尝试使用以下命令安装qt：
sudo apt-get install libqt4-dev libqtwebkit-dev
当我输入qmake --version时，我收到以下消息：
The program 'qmake' is currently not installed. You can install it by typing:
sudo apt-get install qtchooser
据我所知，我已经安装了qt，我尝试运行qtchooser -list-versions并在我的系统中获得以下qt版本列表：
4
5
default
qt4-i386-linux-gnu
qt4-x86_64-linux-gnu
qt4
qt5-x86_64-linux-gnu
qt5
为什么我无法从Ubuntu 14.04中的终端访问 qmake 命令？