$ cat /var/log/nvidia-installer.log

mona@pascal:~$ cat /var/log/nvidia-installer.log
nvidia-installer log file '/var/log/nvidia-installer.log'
creation time: Thu Sep 29 19:30:32 2016
installer version: 367.48

PATH: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

nvidia-installer command line:
    ./nvidia-installer
    --ui=none
    --no-questions
    --accept-license
    --disable-nouveau
    --dkms
    --run-nvidia-xconfig

Using built-in stream user interface
-> Detected 24 CPUs online; setting concurrency level to 24.
-> The file '/tmp/.X0-lock' exists and appears to contain the process ID '1473' of a runnning X server.
ERROR: You appear to be running an X server; please exit X before installing.  For further details, please see the section INSTALLING THE NVIDIA DRIVER in the README available on the Linux driver download page at www.nvidia.com.
ERROR: Installation has failed.  Please see the file '/var/log/nvidia-installer.log' for details.  You may find suggestions on fixing installation problems in the README available on the Linux driver download page at www.nvidia.com.