how to find installed packages on ubuntu system

root@django:/etc/bind# dpkg --get-selections | grep bind
bind9 install
bind9-doc install
bind9-host install
bind9utils install
libbind9-60 install

it will list all packags about bind installed in your system


root@django:/etc/bind# dpkg -L bind9
/etc
/etc/ufw
/etc/ufw/applications.d
/etc/ufw/applications.d/bind9
/etc/apparmor.d
/etc/apparmor.d/force-complain
/etc/apparmor.d/usr.sbin.named
/etc/bind
/etc/bind/bind.keys
/etc/bind/db.0
/etc/bind/db.255
/etc/bind/db.empty
/etc/bind/zones.rfc1918
/etc/bind/db.127
/etc/bind/db.local
/etc/bind/db.root

it will show files within the packages you search