Edited your sources.list in ubuntu but after the apt-get update you receive and error that says :
“GPG error: http://uri intrepid Release: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY ”
You might want to try the following:
gpg –keyserver keyserver.ubuntu.com –recv
gpg –export –armor | sudo apt-key add –
sudo apt-get update