The process had to be done in three parts, and took a quite long time (~3 hours). If you have a slow internet it could take much more. But at least the process was straightforward.
First, I upgraded from 10.04 to 10.10 with this guide (quoted below).
Upgrade from 10.04 LTS to 10.10 - Network Upgrade for Ubuntu Desktops (Recommended)
You can easily upgrade over the network with the following procedure.
- Open the Software Sources application from the System -> Administration menu
- Select the sub menu Updates from the Software Sources application
- Change the Release Upgrade drop down to "Normal Releases" and close the application
- Press Alt-F2 and type update-manager
- Click the Check button to check for new updates.
- If there are any updates to install, use the Install Updates button to install them, and press Check again after that is complete.
- A message will appear informing you of the availability of the new release.
- Click Upgrade.
- Follow the on-screen instructions.
The process took about 40 minutes. I still had to upgrade from 10.10 to 11.04 and from 11.04 to 11.10, so at this point I realized it will take a while.
After the upgrade was ready, I rebooted the computer and once again opened the update-manager and clicked on the "Upgrade" button. The upgrade from 10.10 to 11.04 took about 50 minutes for me.
And then at 11.04, after the reboot, I did the same thing again. Again, the process took about 50 minutes.
So finally I had arrived at 11.10. Things look a lot different now, but it didn't take too long to get used to. And finally the squashfs-tools work!
If you don't know how to see the version of your Ubuntu installation, type cat /etc/issue in a terminal window.