Debian Based Distros

The below command should work for Debain, Ubuntu, and the Raspberry Pi Raspbian.

dpkg --get-selections

RPM Based Distros

The following works on Fedora, CentOS, ReHat.

rpm -qa

The above commands return all of the packages installed on a system.  If you want to look for a specific program or package you can use grep to filter the results.

rpm -qa | grep program

or

dpkg --get-selections | grep program