Sometimes you need some information about your apt-get install / upgrade / remove history. (for example if you destroyed your ROS-Install on your laptop).

By adding a little code snippet to your .bashrc you achieve a very useful tool.

function apt-history(){
      case "$1" in
        install)
              cat /var/log/dpkg.log | grep 'install '
              ;;
        upgrade|remove)
              cat /var/log/dpkg.log | grep $1
              ;;
        rollback)
              cat /var/log/dpkg.log | grep upgrade | 
                  grep "$2" -A10000000 | 
                  grep "$3" -B10000000 | 
                  awk '{print $4"="$5}'
              ;;
        *)
              cat /var/log/dpkg.log
              ;;
      esac
}

Now running

apt-history install
[...]
2014-07-14 19:08:13 install ros-indigo-desktop-full:i386 <none> 1.1.3-0trusty-20140711-1919-+0000

brings you all install entries with timestamp and version information.  Note: instead of install ‘upgrade‘ and ‘remove‘ works too. ‘rollback‘ brings you version information you’ll might need for what I now call downgrade.