Ubuntu Unleashed 2011 Edition: Covering 10.10 and 11.04 (6th Edition)

Like most Ubuntu software, Squid installation is handled through synaptic. After Squid is installed, it is automatically enabled for each boot up. You can check this by running ps aux | grep squid when the machine boots. If for some reason you see nothing there, run /etc/init.d/squid start.