If you want to replicate what packages you have installed from one PC to another or for the purposes of a re-install you can use these:
Backup (list installed packages)
eopkg li | cut -d " " -f 1 | tr '\n' ' ' > ~/InstalledPackages
Copy that InstalledPackages
file from your home folder to your other PC
Restore (install) packages:
sudo eopkg install $(cat InstalledPackages)