Installing the NVIDIA display driver...

It appears that an X server is running. Please exit X before
  installation. If you're sure that X is not running, but are
  getting this error, please delete any X lock files in /tmp.

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= Summary =
===========

Driver:   Installation Failed
Toolkit:  Installation skipped
Samples:  Installation skipped

You need kill lightdm procces. But you need to have some access to shell other than display screen. I usually use ssh from another computer.
sudo apt-get install openssh-server

===========
= Summary =
===========

Driver:   Installed
Toolkit:  Installed in /usr/local/cuda-6.5
Samples:  Installed in /home/makoto/cuda-samples, but missing recommended libraries

Please make sure that
 -   PATH includes /usr/local/cuda-6.5/bin
 - LD_LIBRARY_PATH includes /usr/local/cuda-6.5/lib64, or, add
     /usr/local/cuda-6.5/lib64 to /etc/ld.so.conf and run
     ldconfig as root

To uninstall the CUDA Toolkit, run the uninstall script in /usr/local/cuda-6.5/bin
To uninstall the NVIDIA Driver, run nvidia-uninstall

Please see CUDA_Getting_Started_Guide_For_Linux.pdf in
/usr/local/cuda-6.5/doc/pdf for detailed information on
setting up CUDA.

Logfile is /tmp/cuda_install_9453.log

apt-get install openssh-server
apt-get install dejagnu
apt-get install g++
apt-get install git