The command we need to use is dpkg –get-selections, which will give us a list of all the currently installed packages. $ dpkg --get-selections adduser install alsa-base install alsa-utils install apache2 install apache2-mpm-prefork install apache2-utils install apache2.2-common install apt install apt-utils install The full list can be long and unwieldy, so it’s much easier to filter through grep to get results for the exact package you need. For instance, I wanted to see which php packages I had already installed through apt-get: dpkg --get-selections | grep php libapache2-mod-php5 install php-db ...