Bsrgvty

To get a list of apps that are not in a Registered Repository or PPA do this:

sudo apt-get install apt-show-versions
apt-show-versions | grep 'No available version'

That should output text like this:

app1 1.0.0.14 installed: No available version in archive
app23 0.3.6 installed: No available version in archive
app332 7.0.9377 installed: No available version in archive

For me this worked and showed three apps I installed using DEB packages and weren't available in a Repo or PPA.

Do remember though that it's impossible to check for all programs, only the ones that went through dpkg. For instance, some apps are installed by simply extracting them into the correct folders, or others use a standalone installer bin or script. So the best way is for you yourself to keep a list of apps you installed via any method other than APT.

If you have aptitude installed use,

aptitude search '?obsolete'

or its short form

aptitude search '~o'

Here it is a sample output

i A gcc-4.7-base - GCC, the GNU Compiler Collection (base package)
id libdb4.7 - Berkeley v4.7 Database Libraries [runtime]
i libudev0 - libudev shared library

The first character of each line indicates the current state of the package. The most common states are:

• p, meaning that no trace of the package exists on the system,


• c, meaning that the package was deleted but its configuration files
  remain on the system,


• i, meaning that the package is installed, and


• v, meaning that the package is virtual.

The second character indicates the stored action to be performed on the package, if any, otherwise a blank space is displayed.
The most common actions are:

• i, meaning that the package will be installed,


• d, meaning that the package will be deleted, and


• p, meaning that the package and its configuration files will be removed.

If the third character is A, the package was automatically installed.

For a complete list of the possible state and action flags, see the section Accessing Package Information in the aptitude reference guide.

You could use the following Bash one-liner:

comm -23 <(dpkg-query -W -f '$db:Status-Abbrevt$Packagen' | grep '^.[^nc]' | cut -f2 | sort) <(apt-cache dumpavail | sed -rn 's/^Package: (.*)/1/p' | sort -u)

No need to install extra packages for this, plus this is relatively fast. This will also find partially installed packages (but will not find those that have only configuration files remaining; that could be changed easily, though). Note: this does not care of which architecture the packages are.

Even faster is to use modern apt:

 apt list --installed | awk -F/ '/[installed,local]/print $1'

Yet another option is to run

ubuntu-support-status --show-unsupported

and read the obsolete package names under "No longer downloadable:" section.

More info to investigate.

ubuntu-support-status 
echo "$(sudo apt-mark showmanual | wc -l) packages marked as 'manually installed'."

... ubuntu-support-status and apt-mark may require installation.

There may be a cleaner way, but off the top of my head you can do

dpkg -l | cut -f 3 -d ' ' > installed
xargs -n 1 --replace=X apt-cache search ^X$ < installed | cut -f 1 -d ' ' > available
diff installed available

Cleanup the first few lines of the installed file: it will have headers.

Bonus if anyone can fix my syntax highlighting...

As mentioned apt-get search is not a good method to check if a package is still available. Additional I've added everything to just one line:

for i in `dpkg -l | grep '^i' | awk ' print $2 '`; do apt-cache show $i > /dev/null || echo $i; done