That’s perfectly normal. No one expects you to remember all the
packages installed on your system. But the question arises, how to know
what packages have been installed? How to see the installed packages?
List installed packages in Ubuntu and Debian
If you use apt command extensively, you would probably expect a command like apt list installed packages. You are not entirely wrong here.
While apt-get command doesn’t have a straightforward option like apt-get list installed packages, apt has a command for this.
apt list --installed
This will list all the packages that have been installed using apt.
It will also list the packages that were installed as a dependency.
Which means that not only you’ll have the applications you installed,
you’ll also have a huge list of libraries and other packages that you
didn’t install directly.
Since the list of installed packages is a huge one, it would be a
better idea to use grep and filter the output for a certain package.
If you have read my apt vs apt-get comparison article, you probably already know that both apt and apt-get basically use dpkg. This means you can use dpkg command to list all the installed packages in Debian.
You can filter the output with grep again to search for a specific package.
So far, you have dealt with applications installed with Debian’s
package manager. What about Snap and Flatpak applications? How to list
them because they are not accessible with apt and dpkg?
To show all the Snap packages installed on your system, use this command:
Snap list also indicates which applications are from a verified publisher with a green tick.
You can also use the history of apt command. This will show only the
programs that you installed using apt command. It won’t show the
dependencies installed with it, though the details are present in the
logs. Sometimes, you just want to see that, right?