Important Note: According to the Ubuntu Help:

Please note - this method is much less reliable. If you use this method, you MUST be prepared to fix problems manually, such as packages being unexpectedly removed. Using Update Manager is likely to be much less problematic.

Before you read this HowTo, you may want to consider installing using the GUI with Update Manager, which is probably a simpler method for regular users.

If you are a power user, then let's move on. First, we'll need to install ubuntu-desktop if it's not already installed because otherwise there will be a dependencies problem.

sudo apt-get install ubuntu-desktop

Now we'll need to run a command that will change all the occurrences of dapper to edgy in our sources.list file. If you aren't familiar, sources.list is the file that points to your list of possible upgrades and packages. For windows users, you can think of it as the file that points to Windows Update. Of course, if you are a windows user, you should really install with the Update Manager utility linked above.

sudo sed -e 's/\sdapper/ edgy/g' -i /etc/apt/sources.list

Now we'll perform the actual upgrades:

sudo apt-get update && sudo apt-get dist-upgrade

The && part of the command means that the second command will run after the first as long as the first command completes successfully.

Now we'll finish up the upgrade with a few more commands:

sudo apt-get -f install

sudo dpkg --configure -a

Note that the --configure is actually two dashes. For some reason Wordpress makes it look like a single dash.

Reboot, and you are all done!

Note: I've seen some notes that this upgrade doesn't work very well for people running Ubuntu as a Guest in VMWare with VMWare tools installed. I tested it out and came to the same conclusion, no fix as of yet.

Update:

If upgrading gives you the error message "failed to load module GLcore", you will want to run these commands. Thanks for this tip to Biogeek in the comments below.

apt-get install xfs

apt-get install --reinstall xfonts-base