how to find all downloaded packages in ubuntu code example

Example 1: how to find installed packages in ubuntu

apt list --installed

Example 2: how to check installed packages in linux command

dpkg-query --list | grep -i nano
ii  nano    2.9.3-2    amd64    small, friendly text editor inspired by Pico

Example 3: list apt installed programs

# Use aptitude to get packages which were expressly installed (not just as dependecies)
aptitude search '~i!~M'