How to upgrade your Ubuntu distribution from terminal

Recently I encountered a major Xfce crash. There was no windows decorations nor menus in the graphical environment. I was unable to move windows, as well as close them. It made me realize when I updated my system for the last time. Enough to say that I don't remember this fact. I left the computer for the night to download all packages from 11.04 (Natty Narwhal) and install them (there was surprisingly no option to go directly for 12.04). In the morning my computer was unable to boot with WM and I was left with recovery console... My next easy-to-do option was to try to update to 12.04. Here is what to do (supposing we go from 10.04 (Lucid Lynx) to 12.04 (Precise Pangolin):

sudo sed -i.bak -e s/lucid/precise/g /etc/apt/sources.list
sudo apt-get update
sudo apt-get upgrade
sudo apt-get dist-upgrade

This will not install packages that were earlier not installed. You may have to install for instance kernel image and headers by hand.