Cum sa upgradezi Ubuntu 11.04 la 11.10 (sau versiuni mai noi)

Am in grija un VPS (ca development server) care avea versiunea 11.04 de Ubuntu. 
Ieri m-a rugat acel client sa instalez un pachet nou .. scriu eu repede "apt-get install php5-imap" si boom .. 
 

root@dev008:~# apt-get install php5-imap

Reading package lists... Done
Building dependency tree
Reading state information... Done
The following extra packages will be installed:
  libc-client2007e mlock
Suggested packages:
  uw-mailutils
The following NEW packages will be installed:
  libc-client2007e mlock php5-imap
0 upgraded, 3 newly installed, 0 to remove and 0 not upgraded.
Need to get 808 kB of archives.
After this operation, 1802 kB of additional disk space will be used.
Do you want to continue [Y/n]? y

WARNING: The following packages cannot be authenticated!
  mlock libc-client2007e php5-imap
Install these packages without verification [y/N]? y

Err http://archive.ubuntu.com/ubuntu/ natty/universe mlock amd64
8:2007e~dfsg-3.1ubuntu1
  404  Not Found [IP: 91.189.92.156 80]
Err http://archive.ubuntu.com/ubuntu/ natty/universe libc-client2007e
amd64 8:2007e~dfsg-3.1ubuntu1
  404  Not Found [IP: 91.189.92.156 80]
Err http://archive.ubuntu.com/ubuntu/ natty/universe php5-imap amd64
5.3.5-0ubuntu1
  404  Not Found [IP: 91.189.92.156 80]
Failed to fetch
http://archive.ubuntu.com/ubuntu/pool/universe/u/uw-imap/mlock_2007e~dfsg-3.1ubuntu1_amd64.deb
 404  Not Found [IP: 91.189.92.156 80]
Failed to fetch
http://archive.ubuntu.com/ubuntu/pool/universe/u/uw-imap/libc-client2007e_2007e~dfsg-3.1ubuntu1_amd64.deb
 404  Not Found [IP: 91.189.92.156 80]
Failed to fetch
http://archive.ubuntu.com/ubuntu/pool/universe/p/php-imap/php5-imap_5.3.5-0ubuntu1_amd64.deb
 404  Not Found [IP: 91.189.92.156 80]
E: Unable to fetch some archives, maybe run apt-get update or try with
--fix-missing?

Pasul 1: Cum scapam de 404?

Se pare ca din cauza ca Ubuntu 11.04 e EOL (End of Life) repositories (sursele de pachete sau cum se traduce) au fost mutate in arhive.

sed -i -e 's/archive.ubuntu.com\|security.ubuntu.com/old-releases.ubuntu.com/g' /etc/apt/sources.list

Linia de mai sus schimba pe subdomeniul corect si asa am rezolvat cu 404. Rulati apoi linia de mai jos pentru a actualiza lista de pachete.

apt-get update

Pasul 2: Actualizarea propriu-zisa

Upgradarea la 11.10 se poate face cu comanda 

do-release-upgrade

Daca la rulare va da eroare ca nu gaseste comanda, atunci inseamna ca nu aveti instalat pachetul ce o contine asa ca rulati:

apt-get install update-manager-core

Asta e tot :)

Pasul 3: Atentie!!!

Daca aveti VPS si nu un server dedicat/calculator personal .. atunci intrebati la support daca e ok sau nu sa faceti acest upgrade pentru ca multe companii de hosting folosesc template-uri configurate pentru sistemele lor de virtualizare.