Apt

apt-get

Update the local cache of the repositories:

sudo apt-get update

Update all installed packages

sudo apt-get upgrade

apt-cache

Use to locate packages by searching name and description:

apt-cache search tree

apt-file

Use to locate packages that provide a given file. First you must retrieve the database & indexes:

sudo apt-file update

Then search for the file:

apt-file search rpmbuild

dpkg

To list the installed packages:

dpkg -l