This function might be the most useful one in my own scripts, and I had introduced it for several times.
Let’s say you are working in a big project such as Android Framework, or your are a command-line heavy user. The change-directory-command,
cd, would be typed thounsands times per day. THAT IS SO ANNOYING!.
Try adding this function to ~/.bashrc
suppose you are in
$ .. # will go to L3