A ubuntu hi ha una aplicació que es diu 'Update manager' és a Sistema / Administració

També tens a Aplicacions / Afegir aplicacions

Per afegir aplicacions cal que indiquis d'on les pot treure per tenir-les disponibles per si les necessites instal·lar o actualitzar. Amb aplicacions com aquesta d'afegir aplicacions o el synaptic que és una eina semblant podràs saber què tens instal·lat, que vols actualitzar, desinstal·lar, instal·lar, ...

Però aquestes eines recorren al fitxer /etc/apt/sources.list

Exemple:

deb cdrom:[Ubuntu 5.10 _Breezy Badger_ - Release i386 (20051012)]/ breezy main restricted

## Uncomment the following two lines to fetch updated software from the network
# deb-src http://es.archive.ubuntu.com/ubuntu breezy main restricted

## Uncomment the following two lines to fetch major bug fix updates produced
## after the final release of the distribution.
 deb http://es.archive.ubuntu.com/ubuntu breezy-updates main restricted
# deb-src http://es.archive.ubuntu.com/ubuntu breezy-updates main restricted

## Uncomment the following two lines to add software from the 'universe'
## repository.
## 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
## universe WILL NOT receive any review or updates from the Ubuntu security
## team.
deb http://es.archive.ubuntu.com/ubuntu breezy universe main restricted
# deb-src http://es.archive.ubuntu.com/ubuntu breezy universe

## 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://es.archive.ubuntu.com/ubuntu breezy-backports main restricted universe multiverse
# deb-src http://es.archive.ubuntu.com/ubuntu breezy-backports main restricted universe multiverse

 deb http://security.ubuntu.com/ubuntu breezy-security main restricted
# deb-src http://security.ubuntu.com/ubuntu breezy-security main restricted

 deb http://security.ubuntu.com/ubuntu breezy-security universe
# deb-src http://security.ubuntu.com/ubuntu breezy-security universe

#deb ftp://ftp.ubuntu-es.org/ubuntu/ warty main restricted universe multiverse
#deb ftp://ftp.ubuntu-es.org/ubuntu/ warty-security main restricted