Bonjour!
Mes sincères remerciements pour les précisions (et votre sympathique et appréciée adaptation à mon niveau techno!).
Voilà où cela nous amène:
michel@michel-Latitude-E6420:~$ find /etc/apt -name '*.list' -exec bash -c 'echo -e "\n$1\n"; nl -ba "$1"' _ '{}' \;
/etc/apt/sources.list.d/vertex-theme.list
1 deb http://download.opensuse.org/repositories/home:/Horst3180/xUbuntu_16.04/ /
/etc/apt/sources.list.d/fman.list
1 deb [arch=amd64] https://fman.io/updates/ubuntu/ stable main
/etc/apt/sources.list.d/mhsabbagh-ubuntu-greenproject-xenial.list
1 deb http://ppa.launchpad.net/mhsabbagh/greenproject/ubuntu xenial main
2 # deb-src http://ppa.launchpad.net/mhsabbagh/greenproject/ubuntu xenial main
/etc/apt/sources.list.d/elboulangero-ubuntu-goodvibes-xenial.list
1 deb http://ppa.launchpad.net/elboulangero/goodvibes/ubuntu xenial main
2 # deb-src http://ppa.launchpad.net/elboulangero/goodvibes/ubuntu xenial main
/etc/apt/sources.list.d/captiva-ubuntu-ppa-xenial.list
/etc/apt/sources.list.d/alecive-ubuntu-antigone-xenial.list
/etc/apt/sources.list.d/teejee2008-ubuntu-ppa-xenial.list
1 deb http://ppa.launchpad.net/teejee2008/ppa/ubuntu xenial main
2 # deb-src http://ppa.launchpad.net/teejee2008/ppa/ubuntu xenial main
/etc/apt/sources.list.d/utappia-ubuntu-stable-xenial.list
1 deb http://ppa.launchpad.net/utappia/stable/ubuntu xenial main
2 # deb-src http://ppa.launchpad.net/utappia/stable/ubuntu xenial main
/etc/apt/sources.list.d/moka-ubuntu-daily-xenial.list
1 deb http://ppa.launchpad.net/moka/daily/ubuntu xenial main
2 # deb-src http://ppa.launchpad.net/moka/daily/ubuntu xenial main
/etc/apt/sources.list.d/numix-ubuntu-ppa-xenial.list
1 deb http://ppa.launchpad.net/numix/ppa/ubuntu xenial main
2 # deb-src http://ppa.launchpad.net/numix/ppa/ubuntu xenial main
3 # deb-src http://ppa.launchpad.net/numix/ppa/ubuntu xenial main
/etc/apt/sources.list.d/qtox.list
1 deb http://download.opensuse.org/repositories/home:/antonbatenev:/tox/xUbuntu_16.04/ /
/etc/apt/sources.list.d/ring-nightly-man.list
1 deb https://dl.ring.cx/ring-nightly/ubuntu_16.04/ ring main
/etc/apt/sources.list.d/snwh-ubuntu-pulp-xenial.list
1 deb http://ppa.launchpad.net/snwh/pulp/ubuntu xenial main
2 # deb-src http://ppa.launchpad.net/snwh/pulp/ubuntu xenial main
3 # deb-src http://ppa.launchpad.net/snwh/pulp/ubuntu xenial main
/etc/apt/sources.list.d/noobslab-ubuntu-icons-xenial.list
1 deb http://ppa.launchpad.net/noobslab/icons/ubuntu xenial main
2 # deb-src http://ppa.launchpad.net/noobslab/icons/ubuntu xenial main
/etc/apt/sources.list.d/i-nex-development-team-ubuntu-daily-xenial.list
1 deb http://ppa.launchpad.net/i-nex-development-team/daily/ubuntu xenial main
2 # deb-src http://ppa.launchpad.net/i-nex-development-team/daily/ubuntu xenial main
/etc/apt/sources.list.d/me-davidsansome-ubuntu-clementine-xenial.list
1 deb http://ppa.launchpad.net/me-davidsansome/clementine/ubuntu xenial main
2 # deb-src http://ppa.launchpad.net/me-davidsansome/clementine/ubuntu xenial main
/etc/apt/sources.list.d/dukto.list
1 deb http://download.opensuse.org/repositories/home:/colomboem/xUbuntu_16.04/ /
/etc/apt/sources.list.d/thefanclub-ubuntu-ubuntu-after-install-xenial.list
1 deb http://ppa.launchpad.net/thefanclub/ubuntu-after-install/ubuntu xenial main
2 # deb-src http://ppa.launchpad.net/thefanclub/ubuntu-after-install/ubuntu xenial main
/etc/apt/sources.list.d/atareao-ubuntu-atareao-xenial.list
1 deb http://ppa.launchpad.net/atareao/atareao/ubuntu xenial main
2 # deb-src http://ppa.launchpad.net/atareao/atareao/ubuntu xenial main
/etc/apt/sources.list.d/bablu-boy-ubuntu-nutty_0_1-xenial.list
1 deb http://ppa.launchpad.net/bablu-boy/nutty.0.1/ubuntu xenial main
2 # deb-src http://ppa.launchpad.net/bablu-boy/nutty.0.1/ubuntu xenial main
3 # deb-src http://ppa.launchpad.net/bablu-boy/nutty.0.1/ubuntu xenial main
/etc/apt/sources.list.d/pmjdebruijn-ubuntu-darktable-release-xenial.list
1 deb http://ppa.launchpad.net/pmjdebruijn/darktable-release/ubuntu xenial main
2 # deb-src http://ppa.launchpad.net/pmjdebruijn/darktable-release/ubuntu xenial main
3 # deb-src http://ppa.launchpad.net/pmjdebruijn/darktable-release/ubuntu xenial main
/etc/apt/sources.list.d/retroshare-ubuntu-stable-xenial.list
1 deb http://ppa.launchpad.net/retroshare/stable/ubuntu xenial main
2 # deb-src http://ppa.launchpad.net/retroshare/stable/ubuntu xenial main
3 # deb-src http://ppa.launchpad.net/retroshare/stable/ubuntu xenial main
/etc/apt/sources.list.d/dawidd0811-ubuntu-neofetch-xenial.list
1 deb http://ppa.launchpad.net/dawidd0811/neofetch/ubuntu xenial main
2 # deb-src http://ppa.launchpad.net/dawidd0811/neofetch/ubuntu xenial main
3 # deb-src http://ppa.launchpad.net/dawidd0811/neofetch/ubuntu xenial main
/etc/apt/sources.list.d/oisf-ubuntu-suricata-stable-xenial.list
1 deb http://ppa.launchpad.net/oisf/suricata-stable/ubuntu xenial main
2 # deb-src http://ppa.launchpad.net/oisf/suricata-stable/ubuntu xenial main
/etc/apt/sources.list.d/vivaldi.list
1 ### THIS FILE IS AUTOMATICALLY CONFIGURED ###
2 # You may comment out this entry, but any other modifications may be lost.
3 deb http://repo.vivaldi.com/stable/deb/ stable main
/etc/apt/sources.list.d/plexmediaserver.list
1 # When enabling this repo please remember to add the PlexPublic.Key into the apt setup.
2 # wget -q https://downloads.plex.tv/plex-keys/PlexSign.key -O - | sudo apt-key add -
3 # deb https://downloads.plex.tv/repo/deb/ public main
/etc/apt/sources.list.d/rebuntu16-ubuntu-other-stuff-xenial.list
1 deb http://ppa.launchpad.net/rebuntu16/other-stuff/ubuntu xenial main
2 # deb-src http://ppa.launchpad.net/rebuntu16/other-stuff/ubuntu xenial main
/etc/apt/sources.list.d/gerardpuig-ubuntu-ppa-xenial.list
1 deb http://ppa.launchpad.net/gerardpuig/ppa/ubuntu xenial main
2 # deb-src http://ppa.launchpad.net/gerardpuig/ppa/ubuntu xenial main
/etc/apt/sources.list.d/pcf-ubuntu-miro-releases-xenial.list
/etc/apt/sources.list.d/ravefinity-project-ubuntu-ppa-xenial.list
1 deb http://ppa.launchpad.net/ravefinity-project/ppa/ubuntu xenial main
2 # deb-src http://ppa.launchpad.net/ravefinity-project/ppa/ubuntu xenial main
3 # deb-src http://ppa.launchpad.net/ravefinity-project/ppa/ubuntu xenial main
/etc/apt/sources.list.d/peek-developers-ubuntu-stable-xenial.list
1 deb http://ppa.launchpad.net/peek-developers/stable/ubuntu xenial main
2 # deb-src http://ppa.launchpad.net/peek-developers/stable/ubuntu xenial main
/etc/apt/sources.list.d/tista-ubuntu-adapta-xenial.list
1 deb http://ppa.launchpad.net/tista/adapta/ubuntu xenial main
2 # deb-src http://ppa.launchpad.net/tista/adapta/ubuntu xenial main
/etc/apt/sources.list.d/arc-theme.list
1 deb http://download.opensuse.org/repositories/home:/Horst3180/xUbuntu_16.04/ /
/etc/apt/sources.list.d/ozmartian-ubuntu-apps-xenial.list
1 deb http://ppa.launchpad.net/ozmartian/apps/ubuntu xenial main
2 # deb-src http://ppa.launchpad.net/ozmartian/apps/ubuntu xenial main
/etc/apt/sources.list.d/tox.list
1 deb https://pkg.tox.chat/debian stable xenial
/etc/apt/sources.list.d/noobslab-ubuntu-themes-xenial.list
1 deb http://ppa.launchpad.net/noobslab/themes/ubuntu xenial main
2 # deb-src http://ppa.launchpad.net/noobslab/themes/ubuntu xenial main
3 # deb-src http://ppa.launchpad.net/noobslab/themes/ubuntu xenial main
4 # deb-src http://ppa.launchpad.net/noobslab/themes/ubuntu xenial main
/etc/apt/sources.list
1 # deb cdrom:[Xubuntu 16.04.1 LTS _Xenial Xerus_ - Release amd64 (20160719)]/ xenial main multiverse restricted universe
2
3 # See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
4 # newer versions of the distribution.
5 deb http://ca.archive.ubuntu.com/ubuntu/ xenial main restricted
6 # deb-src http://ca.archive.ubuntu.com/ubuntu/ xenial main restricted
7
8 ## Major bug fix updates produced after the final release of the
9 ## distribution.
10 deb http://ca.archive.ubuntu.com/ubuntu/ xenial-updates main restricted
11 # deb-src http://ca.archive.ubuntu.com/ubuntu/ xenial-updates main restricted
12
13 ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
14 ## team, and may not be under a free licence. Please satisfy yourself as to
15 ## your rights to use the software. Also, please note that software in
16 ## universe WILL NOT receive any review or updates from the Ubuntu security
17 ## team.
18 deb http://ca.archive.ubuntu.com/ubuntu/ xenial universe
19 # deb-src http://ca.archive.ubuntu.com/ubuntu/ xenial universe
20 deb http://ca.archive.ubuntu.com/ubuntu/ xenial-updates universe
21 # deb-src http://ca.archive.ubuntu.com/ubuntu/ xenial-updates universe
22
23 ## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
24 ## team, and may not be under a free licence. Please satisfy yourself as to
25 ## your rights to use the software. Also, please note that software in
26 ## multiverse WILL NOT receive any review or updates from the Ubuntu
27 ## security team.
28 deb http://ca.archive.ubuntu.com/ubuntu/ xenial multiverse
29 # deb-src http://ca.archive.ubuntu.com/ubuntu/ xenial multiverse
30 deb http://ca.archive.ubuntu.com/ubuntu/ xenial-updates multiverse
31 # deb-src http://ca.archive.ubuntu.com/ubuntu/ xenial-updates multiverse
32
33 ## N.B. software from this repository may not have been tested as
34 ## extensively as that contained in the main release, although it includes
35 ## newer versions of some applications which may provide useful features.
36 ## Also, please note that software in backports WILL NOT receive any review
37 ## or updates from the Ubuntu security team.
38 deb http://ca.archive.ubuntu.com/ubuntu/ xenial-backports main restricted universe multiverse
39 # deb-src http://ca.archive.ubuntu.com/ubuntu/ xenial-backports main restricted universe multiverse
40
41 ## Uncomment the following two lines to add software from Canonical's
42 ## 'partner' repository.
43 ## This software is not part of Ubuntu, but is offered by Canonical and the
44 ## respective vendors as a service to Ubuntu users.
45 deb http://archive.canonical.com/ubuntu xenial partner
46 deb-src http://archive.canonical.com/ubuntu xenial partner
47
48 deb http://security.ubuntu.com/ubuntu xenial-security main restricted
49 # deb-src http://security.ubuntu.com/ubuntu xenial-security main restricted
50 deb http://security.ubuntu.com/ubuntu xenial-security universe
51 # deb-src http://security.ubuntu.com/ubuntu xenial-security universe
52 deb http://security.ubuntu.com/ubuntu xenial-security multiverse
53 # deb-src http://security.ubuntu.com/ubuntu xenial-security multiverse
54 deb http://downloads.sourceforge.net/project/xenlism-wildfire/repo deb/
michel@michel-Latitude-E6420:~$
Déjà, le gestionnaire de mises à jour semble avoir apprécié: aucun message d'erreur...
Après sudo apt-get update, j'obtiens:
W: Target Packages (Packages) is configured multiple times in /etc/apt/sources.list.d/arc-theme.list:1 and /etc/apt/sources.list.d/vertex-theme.list:1
W: Target Translations (fr_CA) is configured multiple times in /etc/apt/sources.list.d/arc-theme.list:1 and /etc/apt/sources.list.d/vertex-theme.list:1
W: Target Translations (fr) is configured multiple times in /etc/apt/sources.list.d/arc-theme.list:1 and /etc/apt/sources.list.d/vertex-theme.list:1
W: Target Translations (en) is configured multiple times in /etc/apt/sources.list.d/arc-theme.list:1 and /etc/apt/sources.list.d/vertex-theme.list:1
W: The repository 'http://downloads.sourceforge.net/project/xenlism-wildfire/repo deb/ Release' does not have a Release file.
N: Data from such a repository can't be authenticated and is therefore potentially dangerous to use.
N: See apt-secure(8) manpage for repository creation and user configuration details.
W: http://download.opensuse.org/repositories/home:/colomboem/xUbuntu_16.04/Release.gpg: Signature by key 1A2E38D61775C3963A039A87E3757B8E0D988D6E uses weak digest algorithm (SHA1)
W: Target Packages (Packages) is configured multiple times in /etc/apt/sources.list.d/arc-theme.list:1 and /etc/apt/sources.list.d/vertex-theme.list:1
W: Target Translations (fr_CA) is configured multiple times in /etc/apt/sources.list.d/arc-theme.list:1 and /etc/apt/sources.list.d/vertex-theme.list:1
W: Target Translations (fr) is configured multiple times in /etc/apt/sources.list.d/arc-theme.list:1 and /etc/apt/sources.list.d/vertex-theme.list:1
W: Target Translations (en) is configured multiple times in /etc/apt/sources.list.d/arc-theme.list:1 and /etc/apt/sources.list.d/vertex-theme.list:1
(Je vais de plus me mettre à la lecture des articles cités).
Respectueusement,
Michel Morin