How to list the installed packages on your Raspberry PI?

This is how to list the packages:

• type (in the terminal window):
  dpkg –get-selections
  
• you can limit the search result by using the grep command, for example:
  dpkg –get-selections | grep unzip

That’s it and that’s all!

Resource:
http://www.howtogeek.com/howto/linux/show-the-list-of-installed-packages-on-ubuntu-or-debian/