In case your laptop crashes during your thesis writing it would be nice to have a list of which packets have been installed.

In Ubuntu / Debian or other some other distros there is a tool called dkpg which offers a small command that can be very helpful:

dpkg --get-selections | grep -v deinstall

Saving that list in your backup routine (e.g. of your /home/ dir) every hour using crontab (linux scheduled tasks)

crontab -e
#follow the dialog and add this line to your crontab
0 1 * * * dpkg --get-selections | grep -v deinstall > ~/packages.txt