Installing the CUDA toolkit results in the following instructions being printed to the console.

Please make sure your LD_LIBRARY_PATH
for 64-bit Linux distributions includes /usr/local/cuda-5.0/lib64:/usr/local/cuda-5.0/lib

OR

for 64-bit Linux distributions add /usr/local/cuda-5.0/lib64 and /usr/local/cuda-5.0/lib
to /etc/ld.so.conf and run ldconfig as root

The following code in /etc/profile had no effect.

if [ -z "$LD_LIBRARY_PATH" ]; then    

  LD_LIBRARY_PATH=/usr/local/cuda-5.0/lib64:/usr/local/cuda-5.0/lib

else

  LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/cuda-5.0/lib64:/usr/local/cuda-5.0/lib

fi

export LD_LIBRARY_PATH

That is, rebooting and issuing echo $LD_LIBRARY_PATH showed the variable was not defined.

To try the alternative suggestion, I added the two lines to the file /etc/ld.so.conf so my file looks like this

include /etc/ld.so.conf.d/*.conf 

/usr/local/cuda-5.0/lib64

/usr/local/cuda-5.0/lib

Then I issued:

sudo ldconfig

then

echo $LD_LIBRARY_PATH

Still the environment variable was not set. How do I comply with the CUDA installation instructions shown above?