Installed packages on Ubuntu

How to list all installed packages in Ubuntu?

If you want to know which packages are installed in your Ubuntu box dpkg is a handy tool

dpkg --get-selections

That will list all installed packages in the computer, if you want to narrow your search combine it with grep

dpkg --get-selections | grep php

Provided that you have installed some php packages your output might look like this:

php-apc						install
php-auth-sasl					install
php-mail					install
php-net-smtp					install
php-net-socket					install
php-pear					install
php-xml-parser					install
php5						install
php5-apcu					install
php5-cli					install
php5-common					install
php5-curl					install
php5-dev					install
php5-fpm					install
php5-gd						install
php5-geoip					install
php5-imagick					install
php5-imap					install
php5-json					install
php5-mysql					install
php5-readline					install
pkg-php-tools					install