slackbuilds_ponce/system/listpkg

Listpkg (Lists packages are (installed or not) in Slackware.)

Listpkg is a utility for the Slackware system which lists whether one
or more packages are installed on the system written in sh 'bourne
shell' script.

Simple usage, listpkg [package1] [package2]... example:
$ listpkg kdenlive
$ listpkg audacity kdenlive guvcview