As Ubuntu's TeXLive is quite old (version 2009), I always hear TeX people recommending installing the latest TeXLive directly from CTAN. (Yes, I need the same package mentioned in that question.) I did this, and installed TeXLive 2011.
Now some packages I need to install (e.g. gummi) depend on Ubuntu's TeXLive packages. How can I prevent Ubuntu's TeXLive packages from being installed since I already have a manually installed TeXLive?