I wish there would be a standard tool in Debian or Ubuntu to list all the packages installed since certain date. So that I could use that information to rollback the system state to its original or even a fresh-install state.

Luckily there is a log written with every ever installed, upgraded or removed package by dpkg or apt-get, which can be found at /var/log/dpkg.log. I wrote a simple script that parses the logs and extracts the packages names.

So to list all the packages installed from the beginning of the year:

$ ./dpkg-since.py -n 2015-01-01

Or to clean up the system from anything installed during last two hours:

$ sudo apt-get remove `./dpkg-since.py 2 hours`