How to obtain list of installed packages

[Tom H]

On Wed, May 11, 2016 at 5:54 PM, Ralf Mardorf <silver.bullet at zoho.com> wrote:
> On Wed, 11 May 2016 16:36:48 +0200, Tom H wrote:
>>
>> Did you install "apt"? Isn't it installed?
>>
>> How about "acl", "adduser", "anacron", "apparmor", "apport", ...? (And
>> these are the As that I can remember off-hand.)
>
> I can't speak for Bret, but you might be surprised about my install.
>
> [root at archlinux moonstudio]# systemd-nspawn -q dpkg -l apt aptitude acl adduser anacron apparmor apport
> Desired=Unknown/Install/Remove/Purge/Hold
> | Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
> |/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
> ||/ Name           Version      Architecture Description
> +++-==============-============-============-=================================
> ii  acl            2.2.52-2     amd64        Access control list utilities
> ii  adduser        3.113+nmu3ub all          add and remove users and groups
> un  anacron        <none>       <none>       (no description available)
> un  apparmor       <none>       <none>       (no description available)
> ii  apt            1.0.10.2ubun amd64        commandline package manager
> ii  aptitude       0.7.3-1ubunt amd64        terminal-based package manager
> dpkg-query: no packages found matching apport
> [root at archlinux moonstudio]#

I'm not surprised that you have a non-standard install :)

Both anacron and apparmor are part of an Ubuntu desktop install and
apparmor is part of an Ubuntu standard install:

$ apt-cache show ubuntu-standard | grep Depends
Depends: busybox-static, cpio, cron, dmidecode, dnsutils, dosfstools,
ed, file, ftp, hdparm, info, iptables, language-selector-common,
libpam-systemd, logrotate, lshw, lsof, ltrace, man-db, mime-support,
parted, pciutils, popularity-contest, psmisc, rsync, strace,
systemd-sysv, time, usbutils, wget

$ apt-cache show ubuntu-desktop | grep Depends
Depends: alsa-base, alsa-utils, anacron, at-spi2-core, bc,
ca-certificates, checkbox-gui, dmz-cursor-theme, doc-base,
fonts-dejavu-core, fonts-freefont-ttf, foomatic-db-compressed-ppds,
genisoimage, ghostscript-x, gnome-menus, gnome-session-canberra,
gstreamer1.0-alsa, gstreamer1.0-plugins-base-apps,
gstreamer1.0-pulseaudio, gvfs-bin, inputattach,
language-selector-gnome, libatk-adaptor, libnotify-bin,
libsasl2-modules, lightdm, memtest86+, nautilus, notify-osd,
openprinting-ppds, printer-driver-pnm2ppa, pulseaudio, rfkill,
software-properties-gtk, ubuntu-artwork, ubuntu-drivers-common,
ubuntu-release-upgrader-gtk, ubuntu-session, ubuntu-settings,
ubuntu-sounds, unity, unity-control-center, unity-greeter,
unity-settings-daemon, unzip, update-manager, update-notifier,
wireless-tools, wpasupplicant, xdg-user-dirs, xdg-user-dirs-gtk,
xdiagnose, xkb-data, xorg, yelp, zenity, zip

The point was that there are many packages installed on a system that
aren't explicitly installed by a user.