I’ve upgraded Ubuntu a lot over the years, and often times I’ll start off with a fresh new install, but I really want a list of the old applications I used. Well, ask ubuntu had the answer for me.

https://askubuntu.com/questions/2389/generating-list-of-manually-installed-packages-and-querying-individual-packages


comm -23 <(apt-mark showmanual | sort -u) <(gzip -dc /var/log/installer/initial-status.gz | sed -n 's/^Package: //p' | sort -u)

Now I can sort through the old package installs to see if I need or want all of my old packages.