After a do-release-upgrade, I'm now running ubuntu 12.04 LTS, as indicated below > lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 12.04 LTS Release: 12.04 Codename: precise However, I find that all the entries in my /etc/apt/sources.list were commented out except for one. QUESTION: Is it safe for me to edit these, replacing the old 'lucid' with 'precise' in what is shown below? ## unixteam source list # deb http://debian.yorku.ca/ubuntu/ precise main main/debian-installer restricted restricted/debian-installer # disabled on upgrade to precise # deb-src http://debian.yorku.ca/ubuntu/ precise main restricted # disabled on upgrade to precise # deb http://debian.yorku.ca/ubuntu/ lucid-updates main restricted # disabled on upgrade to precise # deb-src http://debian.yorku.ca/ubuntu/ lucid-updates main restricted # disabled on upgrade to precise # deb http://debian.yorku.ca/ubuntu/ precise universe # disabled on upgrade to precise # deb-src http://debian.yorku.ca/ubuntu/ precise universe # disabled on upgrade to precise # deb http://debian.yorku.ca/ubuntu/ precise multiverse # disabled on upgrade to precise # deb-src http://debian.yorku.ca/ubuntu/ precise multiverse # disabled on upgrade to precise # deb http://debian.yorku.ca/ubuntu lucid-security main restricted # disabled on upgrade to precise # deb-src http://debian.yorku.ca/ubuntu lucid-security main restricted # disabled on upgrade to precise # deb http://debian.yorku.ca/ubuntu lucid-security universe # disabled on upgrade to precise # deb-src http://debian.yorku.ca/ubuntu lucid-security universe # disabled on upgrade to precise # deb http://debian.yorku.ca/ubuntu lucid-security multiverse # disabled on upgrade to precise # deb-src http://debian.yorku.ca/ubuntu lucid-security multiverse # disabled on upgrade to precise # R sources # see http://cran.us.r-project.org/bin/linux/ubuntu/ for details # deb http://probability.ca/cran/bin/linux/ubuntu lucid/ # disabled on upgrade to precise deb http://archive.ubuntu.com/ubuntu precise main multiverse universe