Che cos'è l'aggiornamento del file apt?

Stavo seguendo queste istruzioni e ho installato apt-fileinsieme ad altri pacchetti usando:

sudo apt-get install gnupg pbuilder ubuntu-dev-tools bzr-builddeb apt-file

E ora ogni volta che avvio il mio computer ricevo questo avviso:

Quindi finalmente sono entrato in Terminale e ho digitato il comando:

apt-file update

E ho ottenuto questo risultato:

apt-file is now using the user's cache directory.
If you want to switch back to the system-wide cache directory,
 run 'apt-file purge'
Downloading complete file http://gb.archive.ubuntu.com/ubuntu/dists/utopic/Contents-amd64.gz
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
 94 29.6M   94 27.8M    0     0   667k      0  0:00:45  0:00:42  0:00:03 97 29.6M   97 28.8M    0     0   677k      0  0:00:44  0:00:43  0:00:01 99 29.6M   99 29.5M    0     0   678k      0  0:00:44  0:00:44 --:--:--100 29.6M  100 29.6M    0     0   678k      0  0:00:44  0:00:44 --:--:--  738k
Downloading complete file http://gb.archive.ubuntu.com/ubuntu/dists/utopic-updates/Contents-amd64.gz
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:-- 11 3134k   11  367k    0     0   480k      0  0:00:06 --:--:--  0:00:06 35 3134k   35 1101k    0     0   623k      0  0:00:05  0:00:01  0:00:04 53 3134k   53 1685k    0     0   609k      0  0:00:05  0:00:02  0:00:03 75 3134k   75 2373k    0     0   630k      0  0:00:04  0:00:03  0:00:01 99 3134k   99 3105k    0     0   651k      0  0:00:04  0:00:04 --:--:--100 3134k  100 3134k    0     0   652k      0  0:00:04  0:00:04 --:--:--  684k
Downloading Index http://gb.archive.ubuntu.com/ubuntu/dists/utopic/Contents-amd64.diff/Index:
No Index available.
Downloading complete file http://gb.archive.ubuntu.com/ubuntu/dists/utopic/Contents-amd64.gz
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
File is up-to-date.
Downloading Index http://gb.archive.ubuntu.com/ubuntu/dists/utopic-updates/Contents-amd64.diff/Index:
No Index available.
Downloading complete file http://gb.archive.ubuntu.com/ubuntu/dists/utopic-updates/Contents-amd64.gz
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
File is up-to-date.
Downloading complete file http://gb.archive.ubuntu.com/ubuntu/dists/utopic-backports/Contents-amd64.gz
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--100  121k  100  121k    0     0   189k      0 --:--:-- --:--:-- --:--:--  189k
Downloading complete file http://security.ubuntu.com/ubuntu/dists/utopic-security/Contents-amd64.gz
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:-- 17 2546k   17  452k    0     0   454k      0  0:00:05 --:--:--  0:00:05 46 2546k   46 1185k    0     0   593k      0  0:00:04  0:00:01  0:00:03 75 2546k   75 1918k    0     0   640k      0  0:00:03  0:00:02  0:00:01100 2546k  100 2546k    0     0   660k      0  0:00:03  0:00:03 --:--:--  660k
Downloading Index http://security.ubuntu.com/ubuntu/dists/utopic-security/Contents-amd64.diff/Index:
No Index available.
Downloading complete file http://security.ubuntu.com/ubuntu/dists/utopic-security/Contents-amd64.gz
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--  0     0    0     0    0     0      0      0 --:--:-- --:--:-- --:--:--     0
File is up-to-date.
Ignoring source without Contents File:
  http://extras.ubuntu.com/ubuntu/dists/utopic/Contents-amd64.gz
Ignoring source without Contents File:
  http://dl.google.com/linux/chrome/deb/dists/stable/Contents-amd64.gz

Quindi vedo che dice:

apt-file is now using the user's cache directory.
If you want to switch back to the system-wide cache directory,
 run 'apt-file purge'

Quindi cos'è esattamente apt-file? E cosa significa che ora utilizza la directory della cache dell'utente? È una buona cosa? Qual è la differenza tra la directory cache dell'utente e la directory cache dell'intero sistema e quale dovrei usare? Ciò influisce in qualche modo sulle mie apt-getfonti?

Informazioni sul sistema operativo:

Description:    Ubuntu 14.10
Release:    14.10

Informazioni sul pacchetto:

apt-file:
  Installed: 2.5.2.3ubuntu1
  Candidate: 2.5.2.3ubuntu1
  Version table:
 *** 2.5.2.3ubuntu1 0
        500 http://gb.archive.ubuntu.com/ubuntu/ utopic/universe amd64 Packages
        100 /var/lib/dpkg/status

• apt-fileè usato per fare una ricerca di quale pacchetto fornisce un file. Consideralo la versione offline e piuttosto limitata di http://packages.ubuntu.com .
• Dal momento che hai usato apt-file updatesenza sudo, non può usare una directory di sistema (in genere /var/cache/apt/apt-file), e invece usa una directory nella tua home ( ~/.cache/apt-file).
• Le ricerche di altri utenti non possono utilizzare la cache dell'utente.
• Se sei l'unico utente, non importa quale cache apt-fileusi, purché tu sia coerente sull'uso sudo(o meno).
• apt-gete apt-filecondividere fonti, ma non influisce sull'altro.