Multiple CUDA versions on machine nvcc -V confusion

Question

I used to have cuda-7.0 installed on my machine and later un-installed cuda-7.0 and installed cuda-8.0. When I go to my /usr/local folder I see the following folders:

/bin/ /cuda/ /cuda-7.0/ /cuda-8.0/ /etc/ /games/ /include/ /lib/ /lua/ /man/ /MATLAB/ /sbin/ /share/ /src/ 

I guess I'm confused since the /cuda/version.txt file says it is on cuda-8.0, but when I type:

$ nvcc -V 

it reports that I'm using version 7.0:

nvcc: NVIDIA (R) Cuda compiler driver Copyright (c) 2005-2015 NVIDIA Corporation Built on Mon_Feb_16_22:59:02_CST_2015 Cuda compilation tools, release 7.0, V7.0.27 

What still puzzles me is that even if I do:

export LD_LIBRARY_PATH=/usr/local/cuda-8.0/lib64:$LD_LIBRARY_PATH export PATH=$PATH:/usr/local/cuda-8.0/bin 

after I type $ nvcc -V , it still outputs version 7.0.

Edits:

$ which nvcc /usr/local/cuda-7.0/bin/nvcc  $ echo $PATH /home/arturo/torch/install/bin:/home/arturo/torch/install/bin:/home/arturo/torch/install/bin:/home/arturo/torch/install/bin:/home/arturo/torch/install/bin:/home/arturo/torch/install/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/usr/local/cuda-7.0/bin 

Answer 1

Solution as suggested in the comments:

export PATH=/usr/local/cuda-8.0/bin:$PATH 

The problem was the ordering of $PATH, that my previous command had the =$PATH:/usr/local... instead of =/usr/local....:$PATH

Answer 2

I faced a similar issue after upgrading from cuda-8.0 to cuda-9.2.

Solution is to change the following in .bashrc file:

export CUDA_HOME="/usr/local/cuda-9.2" export LD_LIBRARY_PATH="/usr/local/cuda-9.2/lib64:$LD_LIBRARY_PATH" export PATH="/usr/local/cuda-9.2/bin:$PATH"