How to source the file permanently

edit

This is explained in the Installation tutorial, section 1.6 - Environment setup (here from the Jade tutorial):

It's convenient if the ROS environment variables are automatically added to your bash session every time a new shell is launched:

echo "source /opt/ros/jade/setup.bash" >> ~/.bashrc
source ~/.bashrc

Note also the warning:

If you have more than one ROS distribution installed, ~/.bashrc must only source the setup.bash for the version you are currently using.

If you just want to change the environment of your current shell, you can type:

source /opt/ros/jade/setup.bash

Btw: sourceing is never 'permanent'. It will always only update the shell in which it was invoked.