Una cosa credo utile a chiunque usi Ubuntu, ecco il file standard delle sorgenti sources.list di Ubuntu 11.04 _Natty Narwhal

#deb cdrom:[Ubuntu 11.04 _Natty Narwhal_ - Release i386]/ natty main restricted
# newer versions of the distribution.
deb http://archive.ubuntu.com/ubuntu/ natty main restricted
deb-src http://archive.ubuntu.com/ubuntu/ natty main restricted
## Major bug fix updates produced after the final release of the
## distribution.
deb http://archive.ubuntu.com/ubuntu/ natty-updates main restricted
deb-src http://archive.ubuntu.com/ubuntu/ natty-updates main restricted
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://gb.archive.ubuntu.com/ubuntu/ natty-updates universe
deb-src http://gb.archive.ubuntu.com/ubuntu/ natty-updates universe
## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team, and may not be under a free licence. Please satisfy yourself as to
## your rights to use the software. Also, please note that software in
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb-src http://archive.ubuntu.com/ubuntu/ natty multiverse
deb http://archive.ubuntu.com/ubuntu/ natty-updates multiverse
deb-src http://archive.ubuntu.com/ubuntu/ natty-updates multiverse
## Uncomment the following two lines to add software from the 'backports'
## repository.
## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
deb http://gb.archive.ubuntu.com/ubuntu/ natty-backports main restricted universe multiverse
deb-src http://gb.archive.ubuntu.com/ubuntu/ natty-backports main restricted universe multiverse
## Uncomment the following two lines to add software from Canonical's
## 'partner' repository. This software is not part of Ubuntu, but is
## offered by Canonical and the respective vendors as a service to Ubuntu
## users.
deb http://security.ubuntu.com/ubuntu natty-security main restricted
deb-src http://security.ubuntu.com/ubuntu natty-security main restricted
deb http://security.ubuntu.com/ubuntu natty-security universe
deb-src http://security.ubuntu.com/ubuntu natty-security universe
deb http://security.ubuntu.com/ubuntu natty-security multiverse