pushd and popd are useful when there are more than three directory paths used. However, when you use only two locations, there is an alternative and easier way, that is, cd -.

The current path is /var/www.

    /var/www $  cd /usr/src
/usr/src $ # do something

Now, to switch back to /var/www, you don't have to type /var/www, just execute:

    /usr/src $ cd -

To switch to /usr/src:

    /var/www $ cd -