title: Listing all user-installed packages in Debian
body: <p>For a cyber security competition I participate in, I'm given a Debian virtual machine with many packages installed and asked to clean extraneous or malicious packages.</p>
  <p>In the past, I've used <code>dpkg -l | grep [searchterm]</code> and a list of common packages to preform this task. However, this is extremely inefficient and time-consuming.</p>
  <p>To speed up my task, is there a way to search through the list of packages installed on a system for which processes have been installed by a user and are not system &quot;default&quot; packages?</p>