Installing CUDA on Ubuntu 12.04

• Download the CUDA repository package 
• "cuda-repo-ubuntu1204_6.0-37_amd64.deb" from here developer.nvidia.com/cuda-downloads
• Install it from the terminal:
• $ sudo dpkg -i cuda-repo-ubuntu1204_6.0-37_amd64.deb 
• $ sudo apt-get update 
• Install the CUDA toolkit
• $ sudo apt-get install cuda
• Update the .bashrc file
• export CUDA_HOME=/usr/local/cuda-6.0
• export LD_LIBRARY_PATH=${CUDA_HOME}/lib64   
• PATH=${CUDA_HOME}/bin:${PATH} 
• export PATH
•  Open up a new terminal and copy the SDK samples into the home directory
• $ cuda-install-samples-6.0.sh  ~  
• $ cd ~/NVIDIA_CUDA-6.0_Samples  
• $ make 
• Check the installation success by executing the deviceQuery sample in bin/x86_64/linux/release. 

Reference